WO2015152426A1 - Corrosion-resistant magnesium alloy forged wheel and manufacturing method thereof - Google Patents

Corrosion-resistant magnesium alloy forged wheel and manufacturing method thereof Download PDF

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Publication number
WO2015152426A1
WO2015152426A1 PCT/JP2015/060781 JP2015060781W WO2015152426A1 WO 2015152426 A1 WO2015152426 A1 WO 2015152426A1 JP 2015060781 W JP2015060781 W JP 2015060781W WO 2015152426 A1 WO2015152426 A1 WO 2015152426A1
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Prior art keywords
magnesium alloy
alloy forged
chemical conversion
layer
wheel
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PCT/JP2015/060781
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French (fr)
Japanese (ja)
Inventor
陽 曽根崎
健樹 松村
信次 難波
厚志 栢本
允康 八尾
Original Assignee
Ｂｂｓジャパン株式会社
ミリオン化学株式会社
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Publication of WO2015152426A1 publication Critical patent/WO2015152426A1/en

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates
    • C23C22/22—Orthophosphates containing alkaline earth metal cations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • B05D7/16—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies using synthetic lacquers or varnishes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B3/00—Disc wheels, i.e. wheels with load-supporting disc body
    • B60B3/02—Disc wheels, i.e. wheels with load-supporting disc body with a single disc body integral with rim
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B7/00—Wheel cover discs, rings, or the like, for ornamenting, protecting, venting, or obscuring, wholly or in part, the wheel body, rim, hub, or tyre sidewall, e.g. wheel cover discs, wheel cover discs with cooling fins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2350/00—Pretreatment of the substrate
    • B05D2350/60—Adding a layer before coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/50—Multilayers
    • B05D7/51—One specific pretreatment, e.g. phosphatation, chromatation, in combination with one specific coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2310/00—Manufacturing methods
    • B60B2310/60—Surface treatment; After treatment
    • B60B2310/614—Painting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2310/00—Manufacturing methods
    • B60B2310/60—Surface treatment; After treatment
    • B60B2310/616—Coating with thin films
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon

Definitions

  • the present invention relates to a corrosion-resistant magnesium alloy forged wheel.
  • the present invention relates to a magnesium alloy forged wheel that is ultralight and excellent in corrosion resistance and a method for manufacturing the same. More specifically, the present invention relates to a magnesium alloy forged wheel for automobiles and a manufacturing method thereof.
  • Mg wheels alloy wheels containing magnesium
  • Mg wheel itself has already been adopted in racing cars such as the F1 World Championship, which is the highest car racing sponsored by the International Automobile Federation (FIA).
  • F1 World Championship which is the highest car racing sponsored by the International Automobile Federation (FIA).
  • Mg wheels have not been widely used in the general market because they do not have the versatility required for general passenger cars because they are expensive and have poor corrosion resistance.
  • Mg wheel contains magnesium.
  • Magnesium unlike aluminum, easily forms an oxide film on its surface and is extremely vulnerable to salt and corrosion. For this reason, processing, such as a coating process and a rust prevention process, must be beforehand performed on the Mg wheel surface. If the surface layer of the Mg wheel surface peels off, it must be repaired promptly. The reason for this is that when magnesium on the surface of the Mg wheel is exposed to the atmosphere, the magnesium reacts with moisture, oxygen, etc. to cause corrosion and rust, and the mechanical strength and the like of the Mg wheel rapidly decrease. In addition, when an automobile equipped with an Mg wheel is used in a salty environment such as along the coast, it must be frequently washed.
  • the Mg wheel is superior in being lightweight, but the corrosion resistance (for example, salt spray test) is practically seen. Not enough and extremely inferior to aluminum wheels.
  • the present invention has been made in view of such technical circumstances, and has solved problems in conventional magnesium alloy wheels, is ultralight, and has improved corrosion resistance over a long period of time, such as warm water resistance and rust resistance. It is an object to provide a magnesium alloy forged wheel and a method for manufacturing the same.
  • the present inventor has formed a conversion coating layer containing calcium, manganese, and phosphorus formed on a magnesium alloy forging material and a conversion coating layer as a member of a magnesium alloy forging wheel. It was found that it was ultra-lightweight by being provided with the prepared primer layer, and corrosion resistance over a long period of time such as warm water resistance and rust resistance could be improved, and the present invention was completed. More specifically, the present invention comprises the following technical matters.
  • a corrosion-resistant magnesium alloy forged wheel comprising a chemical conversion film layer containing calcium, manganese and phosphorus formed on a magnesium alloy forging material, and a primer layer formed on the chemical conversion film layer,
  • the magnesium alloy forging material contains magnesium particles having an average crystal particle diameter of 80 ⁇ m or less on the surface thereof,
  • the weight ratio of calcium / manganese adhesion contained in the chemical conversion coating layer is 0.40 to 0.60
  • the primer layer comprises an epoxy resin-based primer paint containing an epoxy resin having a weight average molecular weight of 30,000 or less and containing an antirust pigment of 5.0 wt% or less.
  • the conversion coating layer is calcium 1 ⁇ 150mg / m 2, manganese 2 ⁇ 380 mg / m 2, characterized in that the phosphorus containing 1 ⁇ 600mg / m 2 (1 ) corrosion resistance of magnesium alloy forged according wheel.
  • the surface of the magnesium alloy forged wheel material having an average crystal particle size of 80 ⁇ m or less is brought into contact with a chemical conversion treatment solution containing calcium ions, manganese ions and phosphate ions, and calcium is deposited on the magnesium alloy forged wheel material.
  • a step of forming a chemical conversion film having a calcium / manganese adhesion weight ratio of 0.40 to 0.60, and an epoxy resin having a weight average molecular weight of 30,000 or less on the chemical conversion film And a step of applying an epoxy resin-based primer paint containing 5.0 wt% or less of an anticorrosive pigment to form a primer layer, and a method for producing a corrosion-resistant magnesium alloy forged wheel.
  • a magnesium alloy forged wheel that is ultralight and has excellent corrosion resistance over a long period of time, such as warm water resistance and rust resistance.
  • FIG. 1 is a model diagram showing the leg circumference of an automobile equipped with a magnesium alloy forged wheel.
  • a tire 2 is mounted around the magnesium alloy forged wheel 1 in the X-axis direction.
  • the magnesium alloy forged wheel 1 and the tire 2 are mounted at four locations on the front, rear, left and right sides of the automobile V as a set.
  • FIG. 2 is a schematic view showing a cross-sectional structure of the magnesium alloy forged wheel.
  • a chemical film layer 20 is laminated on the magnesium alloy forged material 10
  • a primer layer 30 is further laminated on the chemical film layer 20.
  • the magnesium alloy forging material 10, the chemical conversion film layer 20, and the primer layer 30 are integrated together to form the magnesium alloy forged wheel 1 while being in close contact with each other.
  • the magnesium alloy forged wheel 1 will be described in detail.
  • the magnesium alloy forged wheel of the present invention is attached to automobiles such as passenger cars, motorcycles, buses, trucks, wagon cars, and vehicles such as bicycles.
  • automobiles such as passenger cars, motorcycles, buses, trucks, wagon cars, and vehicles such as bicycles.
  • it is a magnesium alloy forged wheel that meets all the needs required when it is used as a forged wheel for automobiles, is ultra-lightweight, and has excellent corrosion resistance over a long period of time, such as warm water resistance and rust resistance.
  • FIG. 3 is an enlarged model view of the cross-sectional structure of the magnesium alloy forged wheel 1.
  • the magnesium alloy forged wheel 1 of the present invention is formed on the conversion coating layer 20 containing calcium, manganese and phosphorus formed on the magnesium alloy forging material 10 and on this conversion coating layer 20. And a primer layer 30.
  • each layer provided in the magnesium alloy forged wheel 1 will be described.
  • the magnesium alloy used as the material (billet) of the magnesium alloy forged wheel material 10 is an alloy containing magnesium as a main component. Specifically, the magnesium alloy contains magnesium in an amount of 90% by weight or more, and contains other components such as aluminum (Al), zinc (Zn), manganese (Mn) in a small amount, preferably 10% by weight or less. Some alloys are also included.
  • a magnesium alloy such as a two-component Mg—Zn alloy, a three-component Mg—Al—Zn alloy, or a four-component Mg—Al—Zn—Mn alloy may also be used.
  • the magnesium alloy may contain other elements such as Ni, Fe, Cu, Si, etc. in the amount of impurities (for example, 0.01% by weight or less).
  • the material (billet) of the magnesium alloy forged wheel material 10 is particularly formed by a one-way or two-way forging method.
  • the forging ratio when forming the magnesium alloy forged wheel 1 is 1 to 15, preferably 3 to 10, and more preferably 4 to 7.
  • the magnesium alloy forged wheel material is the primary structure of the wheel by applying a pressure of 3,500 to 5,000 kg / cm 2 while heating the material (billet) of the magnesium alloy forged wheel material 10 to 300 to 400 ° C. Manufactured through a process of forming a tertiary structure and a spinning process.
  • the material (billet) of the magnesium alloy forged wheel material 10 includes magnesium particles having an average crystal particle diameter of about 300 ⁇ m. By forging this, the average crystal particle diameter can be reduced to 30 to 80 ⁇ m in the unidirectional forging, and the average crystal particle diameter can be reduced to 10 to 30 ⁇ m in the two-way forging. If the average crystal particle diameter is less than 10 ⁇ m, the magnesium particles become extremely dense and air holes are not formed, so the strength of the magnesium alloy forged wheel is improved, but the adhesion to the upper chemical conversion coating layer and primer layer is improved. Is not preferred because it is difficult to obtain. Further, if the average crystal particle diameter exceeds 80 ⁇ m, it becomes easy to control the average crystal particles of the magnesium particles, but it is not preferable because the strength of the magnesium alloy forged wheel material 10 is lowered.
  • FIG. 4 is an IPF map showing the average crystal grain size of magnesium in the spoke part of the magnesium alloy forged wheel 1 produced by the two-way forging method. According to FIG. 4, it can be understood that the average crystal grain size of magnesium in the spoke portion of the magnesium alloy forged wheel 1 is 12 ⁇ m.
  • the magnesium alloy forged wheel 1 a homogeneous and stable metal structure is adopted by adopting magnesium particles having a specific average crystal particle radius as the magnesium particles constituting the material (billet) of the magnesium alloy forged wheel material 10.
  • the ultra-lightweight, forged magnesium alloy wheel is realized.
  • strength can be manufactured by employ
  • the magnesium alloy forged wheel 1 of the present invention includes a chemical conversion coating layer 20 on a magnesium alloy forged wheel material 10.
  • the chemical conversion film layer 20 contains calcium, manganese, and phosphorus. Calcium, manganese and phosphorus contained in the chemical conversion coating layer 20 form a stable crystal structure as a result of interaction with magnesium particles present on the surface of the magnesium alloy forged wheel material 10. As a result, the magnesium alloy forged wheel material 10 and the chemical conversion film layer 20 are fixed.
  • Calcium contained in the chemical conversion coating layer 20 the content of manganese and phosphorus, calcium each 1 ⁇ 150mg / m 2, preferably 10 ⁇ 110mg / m 2, manganese 2 ⁇ 380mg / m 2, preferably 20 It is preferably ⁇ 280 mg / m 2 and phosphorus is 1.0 to 600 mg / m 2 , preferably 10 to 400 mg / m 2 .
  • the content of calcium, manganese and phosphorus contained in the chemical conversion film layer 20 is within the above range, the three components of calcium, manganese and phosphorus are stabilized in the chemical conversion film layer 20, and these three components and magnesium alloy forging This is preferable because a stable crystal structure can be formed with the magnesium particles constituting the material (billet) of the wheel material 10.
  • the contents of calcium, manganese and phosphorus contained in the chemical conversion film layer 20 were measured by a fluorescent X-ray (XRF) analysis method. Specifically, using a calibration curve method based on a fluorescent X-ray (XRF) analysis method, the fluorescent X-ray (XRF) intensity of a standard sample with a known content is measured, and the content of this standard sample and the fluorescent X-ray ( A calibration curve was prepared based on the measured intensity of (XRF). The fluorescence X-ray intensity of the unknown element material of the chemical conversion film layer 20 was measured, and the amount of adhesion was determined using a calibration curve. This was used as the content of calcium, manganese and phosphorus contained in the chemical conversion film layer 20.
  • XRF fluorescent X-ray
  • the amount of calcium and manganese contained in the chemical conversion coating layer 20 that adheres to the surface of the magnesium alloy forged wheel material 10 is preferably 0.40 to 0.60 in weight ratio (calcium / manganese). More preferably, it is 0.45 to 0.55.
  • a weight ratio (calcium / manganese) of 0.40 or more is preferable because a stable crystal structure can be formed with magnesium particles constituting the material (billet) of the magnesium alloy forged wheel material 10, and is preferably 0.60 or less. It is preferable because the rust resistance of the magnesium alloy forged wheel 1 is improved.
  • the film thickness of the chemical conversion film layer 20 is not particularly limited, but is preferably 1.0 to 3.0 ⁇ m.
  • the magnesium alloy forged wheel 1 of the present invention includes a primer layer 30 on the chemical conversion film layer 20.
  • the primer layer 30 is a layer formed by applying an epoxy resin-based primer paint on the chemical conversion film layer 20.
  • the epoxy resin contained in the primer layer 30 includes an epoxy resin having a weight average molecular weight of 30,000 or less, preferably 9,000 to 10,000, and derivatives thereof.
  • an epoxy resin having a weight average molecular weight of about 10,000 is particularly preferable.
  • the uniform primer layer 30 can be applied even to the details of the magnesium alloy forged wheel material 10 having a complicated shape that is shaped according to any vehicle model and application. Can be formed.
  • Examples of the epoxy resin contained in the primer layer 30 include an epoxy resin containing a glycidyl group represented by the following general formula.
  • Z represents a hydrogen atom, a methyl group or an ethyl group.
  • the epoxy resin contained in the primer layer 30 is a compound having at least one substituted or unsubstituted glycidyl group represented by the above general formula in the molecule.
  • the epoxy resin can take, for example, a glycidyl ether type, a glycidyl ester type, a glycidyl amine type, and a glycidyl imine type.
  • an epoxy resin-based primer coating having a specially modified epoxy resin-based varnish as a main ingredient, polymerized to a weight average molecular weight of about 10,000 to 20,000, and added with a melamine resin-based varnish to increase the crosslinking density is used.
  • an epoxy resin primer paint (trade name: BS primer, manufactured by Dainippon Paint Co., Ltd.) can be used.
  • the primer layer 30 is characterized by not containing a rust preventive pigment or containing 5.0 wt% or less of a rust preventive pigment.
  • the magnesium alloy forged wheel 1 is ultralight and has excellent corrosion resistance over a long period of time, such as warm water resistance and rust resistance, but the magnesium alloy particles constituting the material (billet) of the magnesium alloy forged wheel material 10 And by providing the chemical conversion film layer, corrosion resistance over a long period of time, such as sufficient hot water resistance and rust resistance, can be realized even if no rust preventive pigment is contained.
  • the primer layer 30 may contain a polyamide curing agent.
  • a polyamide curing agent a polyamide having an average of 1.7 or more primary amino groups or secondary amino groups per molecule can be employed.
  • polymerized fatty acids such as linoleic acid, oleic acid, linoleic acid, elaidic acid, ricinoleic acid and the like, which are obtained by polymerizing a higher fatty acid having an unsaturated bond, such as dimer acid and trimer acid, and polyamines, in particular Examples thereof include condensation products with fatty acid polyamines.
  • the following shows polyamides using linolenic acid dimer acid.
  • R 1 and R 2 may be the same or different and are polyamine residues.
  • the primer layer 30 may contain a curing aid and / or a curing accelerator.
  • curing aids include BF 3 -amine complexes, hexahydrophthalic anhydride, dicyandiamide, imidazoles such as 2-ethyl-4-methylimidazole, and the like.
  • curing accelerator include triethyltetramine, modified fatty acid polyamine, modified aromatic polyamine and the like.
  • the primer layer 30 may contain a chain extender and / or a crosslinking agent in order to adjust the degree of crosslinking of the epoxy resin.
  • the chain extender is not particularly limited as long as it can adjust the degree of crosslinking of the epoxy resin, but is not limited to dibasic acids such as azelaic acid and fumaric acid, 1,6-hexanedidiol, , 8-octanediol and other dimercaptans, maleic anhydride, succinic anhydride, phthalic anhydride, hexahydrophthalic anhydride and other acid anhydrides, diisocyanates, aliphatic amines, aliphatic polyamines, alicyclic Examples include diamines, alicyclic polyamines, heterocyclic diamines, heterocyclic polyamines, aliphatic dihalogen compounds having 1 to 12 carbon atoms, and dihydroxy aromatic compounds having 6 to 18 carbon atoms.
  • the primer layer 30 may contain an inorganic pigment as necessary.
  • the inorganic pigment is not particularly limited as long as it does not lower the performance required for the primer layer 30, but is a color pigment such as titanium oxide, zinc white, iron oxide, phthalocyanine blue, and benzidine yellow, quartz Examples include extender pigments such as powder, alumina oxide and precipitated barium sulfate, metal powders such as stainless powder, zinc powder, aluminum powder and mica, and rust preventive pigments such as zinc oxide, zinc phosphate, lead and tripolyphosphoric acid. it can.
  • the primer layer 30 is obtained by applying a primer paint as a raw material for the primer layer on the chemical conversion film layer 20 and then drying it.
  • the solvent contained in the primer paint is not particularly limited as long as a primer paint having an appropriate viscosity can be obtained, but hydrocarbon solvents such as toluene and xylene, butyl acetate and the like. Examples thereof include ester solvents, ketone solvents such as methyl ethyl ketone, cyclohexane and isophorone, and alcohol solvents such as methanol, ethanol and butanol.
  • the film thickness of the primer layer 30 is not particularly limited, but is preferably 10 to 30 ⁇ m. If the thickness of the primer layer 30 is less than 10 ⁇ m, corrosion resistance over a long period of time such as warm water resistance and rust resistance cannot be improved, and if it exceeds 30 ⁇ m, the magnesium alloy forged wheel 1 is reduced in weight and coated. This is not preferable because the adhesion of the film cannot be improved.
  • the magnesium alloy forged wheel 1 according to the present invention includes a conversion coating layer 20 containing calcium, manganese, and phosphorus formed on a magnesium alloy forging material 10 and a primer layer 30 formed on the conversion coating layer 20 as a basic layer A.
  • a protective layer 40 may be provided on the primer layer 30.
  • FIG. 5 the enlarged model figure of the cross-section of the magnesium alloy forge wheel 1 provided with the protective layer 40 was shown.
  • the magnesium alloy forged wheel 1 shown in FIG. 5 includes an intermediate coating layer 40 a and a top coating layer 40 b as the protective layer 40.
  • the intermediate coating layer 40a has a role of adjusting the coating color of the magnesium alloy forged wheel 1 and further improving the coating hardness. Further, the top coat layer 40b has a role of improving the appearance of the magnesium alloy forged wheel 1 and the surface hardness of the wheel.
  • the magnesium alloy forged wheel 1 of the present invention is provided with the protective layer 40, so that in addition to long-term corrosion resistance required for automobile wheels, such as ultra-lightening, hot water resistance, rust resistance, etc., From the viewpoint of the design characteristics exhibited by the magnesium alloy forged wheel 1, the product has functional beauty and decorative beauty.
  • the intermediate coating layer 40a may be formed as the intermediate coating layer 40a by using the primer layer 30 as an undercoat layer and, if desired, applying an acrylic resin powder coating on the primer layer 30.
  • an acrylic resin type powder coating material (For example, brand name: Evaclad EV5600DK, Kansai Paint Co., Ltd. product) etc. can be used.
  • the average coating thickness of the intermediate coating layer is not particularly limited and can be appropriately changed according to the application of the magnesium alloy forged wheel 1, but is usually 60 to 100 ⁇ m.
  • a top coating layer 40b may be formed on the intermediate coating layer 40a.
  • the top coating layer 40b is mainly for imparting a cosmetic effect, and a coating material known per se for improving an excellent coating appearance and surface strength can be used.
  • a liquid paint using an organic solvent and / or water as a solvent or a dispersion medium is preferably used.
  • the top coating is a composition containing an acrylic resin as a main component, and further contains a color pigment, a metallic pigment, or the like as necessary.
  • the resin composition comprises a base resin and a curing agent.
  • the base resin examples include acrylic resins, alkyd resins, polyester resins, fluororesins, and Si-containing resins
  • preferred examples of the curing agent include amino resins and polyisocyanate compounds (including block compounds).
  • an acrylic resin-based colored solvent paint for example, trade name: Magiclon AL-2200, manufactured by Kansai Paint Co., Ltd.
  • an acrylic resin-based clear coat solvent paint is further applied. Can do.
  • the protective layer 40 laminated on the primer layer 30 is not limited to the variations of the intermediate coating layer 40a and the top coating layer 40b.
  • the protective layer 40 laminated on the primer layer 30 can take various forms depending on the use of the magnesium alloy forged wheel having a complicated shape devised in accordance with any automobile model. Specifically, the protective layer 40 may be added to the intermediate coating layer 40a and the top coating layer 40b, and a protective layer having a new function may be laminated on the uppermost layer of the protective layer 40. You may laminate
  • the method for producing a magnesium alloy forged wheel according to the present invention includes a step (i) of surface-treating a magnesium alloy forged material, a step (ii) of pre-treating the magnesium alloy forged material after the surface treatment step (forming a conversion coating layer), and undercoating It includes a step (iii) (primer layer formation) and, if desired, a protective layer formation step (iv) (intercoat layer formation and / or overcoat layer formation).
  • a protective layer formation step iv
  • the step of surface-treating the magnesium alloy forging material 10 is to physically remove impurities adhering to the surface of the magnesium alloy forging material 10 and to improve the adhesion with a chemical conversion film layer, a primer layer, etc. to be formed later. With the goal. Furthermore, it is performed in order to make the unevenness of the surface of the magnesium alloy forging material 10 uniform and improve the appearance of the painted surface after painting.
  • blasting is generally used as the surface treatment.
  • the blasting treatment has an anchor effect by removing impurities and roughening the surface of the material, and is a method of spraying sandy stainless steel, zircon and alundum particles onto the material surface at high pressure.
  • the magnesium alloy forging material 10 preferably uses zircon or alumina oxide particles.
  • Step (ii) of pre-processing the magnesium alloy forging material 10 The chemical conversion coating layer 20 is formed on the surface-treated magnesium alloy forging material 10 by the step of pretreating the magnesium alloy forging material 10.
  • the pretreatment step includes the following steps (ii) -1 to (ii) -3. Specifically, after the degreasing treatment, washing with water and surface adjustment are repeated once or several times, and after washing with water, a chemical conversion film treatment is performed. After the chemical conversion film treatment, it is subjected to the next painting step after washing with warm water, air blowing and drying.
  • Step (ii) -1 The degreasing treatment is usually an alkaline bath solution having a pH of about 10 to 13, such as an aqueous sodium hydroxide solution, and an alkaline bath at a temperature of room temperature to 50 ° C., for example, 40 to 45 ° C. It is performed using a liquid. Moreover, the method of performing bath solution pH for degreasing at 13 or more is also included. According to this method, by performing the degreasing treatment on the magnesium alloy forging material 10 in the passive state region, it is possible to obtain a more stable chemical conversion coating layer 20 in the chemical conversion coating treatment of the next step. In order to raise pH to 13 or more about this degreasing bath liquid, it can be based on increasing the compounding quantity, such as caustic.
  • Step (ii) -2 For the surface adjustment, an inorganic acid and / or an organic acid can be used.
  • the inorganic acid include sulfuric acid and phosphoric acid.
  • the organic acid include citric acid, malic acid, gluconic acid, acetic acid and the like.
  • Step (ii) -3 The chemical conversion film treatment includes calcium ions (Ca 2+ ), manganese ions (Mn 2+ ), and phosphate ions (PO 4 3 ⁇ ), and the weight ratio of Ca / Mn is 0.5 or less.
  • the Mg alloy material is treated with an aqueous chemical conversion treatment solution of 0.40 to 0.50.
  • the aqueous chemical conversion treatment solution has a calcium ion of 0.3 to 0.6 g / l, a manganese ion of about twice the calcium ion, that is, 0.6 to 1.2 g / l, and a phosphate ion of 10 g / l or more.
  • the calcium ion source one or more of calcium nitrate, calcium nitrite, calcium thiosulfate and dicalcium phosphate can be used, and calcium nitrate is preferred.
  • the manganese ion source one or more of manganese nitrate, manganese hydrogen phosphate, manganese biphosphate, and manganese borofluoride can be used, and manganese nitrate is preferable.
  • the phosphate ion source one or more of orthophosphoric acid, condensed phosphoric acid, phosphorous acid and hypophosphorous acid can be used, and orthophosphoric acid is preferred.
  • the chemical conversion solution is adjusted to a pH of 1.0 to 3.0.
  • a chemical conversion coating layer can be formed effectively and without hindrance on the surface of the magnesium alloy forging material 10.
  • the temperature conditions of this chemical conversion liquid have a correlation with the contact time with the magnesium alloy forging raw material 10 surface used as the to-be-processed material surface.
  • the contact time is preferably longer, and when the bath liquid temperature is about 80 ° C., the contact time is preferably shorter. It has become a relationship.
  • the contact is preferably performed at a temperature of room temperature or higher, preferably 30 ° C. or higher and 80 ° C. or lower for 1 to 10 minutes, particularly 45 to 55 ° C. for 1 to 5 minutes.
  • a temperature of room temperature or higher preferably 30 ° C. or higher and 80 ° C. or lower for 1 to 10 minutes, particularly 45 to 55 ° C. for 1 to 5 minutes.
  • the temperature of the chemical conversion treatment liquid is less than 30 ° C., it takes a long time to form the chemical conversion film, and the performance required for the obtained chemical conversion film layer becomes insufficient.
  • the temperature exceeds 80 ° C. the performance of the chemical conversion film obtained by excessive reaction may be reduced.
  • calcium is 1 to 150 mg / m 2 , preferably 10 to 110 mg / m 2
  • manganese is 2 to 380 mg / m 2 , preferably 20 to 280 mg / m 2
  • phosphorus is 1 to 600 mg / m 2.
  • Primer layer 30 forming step (iii) In the primer layer 30 forming step (iii), the magnesium alloy forged material 10 on which the chemical conversion film layer 20 has been formed in the pretreatment step (ii) is washed with warm water and air blow dried, and then an epoxy resin primer coating is applied to the primer layer 30 30.
  • the epoxy resin described above can be used as the epoxy resin.
  • the primer layer 30 is formed by applying on primer (usually 4 to 5 minutes on the room temperature drying line process) or drying conditions at 100 ° C. for 20 to 30 minutes after the primer coating is applied.
  • the average coating film thickness of the primer layer 30 depends on the target product, but in the case of a wheel, it is 10 to 20 ⁇ m.
  • FIG. 6 is an enlarged model diagram of a cross-sectional structure of the magnesium alloy forged wheel 1 provided with a protective layer.
  • the magnesium alloy forged wheel 1 of the present invention forms an intermediate coating layer 40 a to be a protective layer 40 by coating an acrylic resin powder coating on the material on which the primer layer 30 is formed, if desired. can do.
  • acrylic resin-based powder coatings can be used.
  • trade names: EVA Clad EV5600DK, manufactured by Kansai Paint Co., Ltd., and the like can be used.
  • the average coating thickness of the intermediate coating layer serving as the protective layer 40 is usually 60 to 100 ⁇ m.
  • the top coating layer 40b can be formed on the material on which the intermediate coating layer 40a is formed.
  • This top coating is mainly for imparting a cosmetic effect, improves the appearance of the coating and the surface strength, and a coating known per se can be used.
  • a liquid paint using an organic solvent and / or water as a solvent or a dispersion medium is preferably used.
  • the components of the top coating composition are as described above.
  • the magnesium alloy forged wheel 1 was manufactured by the manufacturing method of the said magnesium alloy forged wheel.
  • the magnesium alloy forging material 10 a magnesium alloy according to ASTM standard product AZ80 was used. This magnesium alloy was molded by a unidirectional forging method at a forging ratio of about 6. The average crystal particle diameter of magnesium particles contained in the magnesium alloy was made 60 ⁇ m to make fine particles.
  • the component of the magnesium alloy forging material 10 is 0.005 wt% or less of iron (Fe), 0.055 wt% or less of copper (Cu), and 0.005 wt% or less of nickel (Ni).
  • the treatment liquid used to form the chemical conversion film layer 20 was a manganese calcium phosphate treatment liquid (trade name: Grander MC-1000W, manufactured by Million Chemical Co., Ltd.). After the magnesium alloy forged material 10 is degreased and brought into contact with the above treatment liquid, washing with water and the following surface adjustment are repeated once or twice, and after washing with water, the conversion coating layer 20 before drying is formed on the magnesium alloy forged material 10. Formed. The chemical conversion film layer 20 was further washed with warm water, then air blown and dried to form the chemical conversion film layer 20 on the magnesium alloy forging material 10. Specifically, the procedure was as follows.
  • Manganese calcium phosphate system treatment Ion-exchanged water is used and stirred for 3 minutes at 50 ° C.
  • Pure water washing shower water washing using ion exchange water for 30 seconds.
  • Pure water washing Ion-exchange water is used, and immersion water washing is performed at 50 ° C for 1 minute.
  • Air blow Water droplets adhering to the surface or water in the pool are blown off with air for about 15 seconds.
  • Drying Drying with hot air at 80 ° C. for 15 to 30 minutes.
  • a primer layer 30 was formed on the chemical conversion film layer 20 formed on the magnesium alloy forging material 10.
  • the primer layer 30 was formed by applying an epoxy resin primer to the chemical conversion coating layer 20 by the following method using the coating types shown in Table 2 below.
  • the epoxy resin-based primer paint (trade name: BS primer, manufactured by Dainippon Paint Co., Ltd.) has a specially modified epoxy resin-based varnish as the main agent, and has a weight average molecular weight of about 9,000 to 10,000. A paint to which a melanin resin varnish was added was used.
  • an acrylic resin powder coating (trade name: Evaclad EV5600DK, manufactured by Kansai Paint Co., Ltd.) was used and baked for 40 minutes at 160 ° C. under dry conditions (intermediate coating 1).
  • an acrylic resin-based primer solvent paint (trade name: Magiclon ALC-2, manufactured by Kansai Paint Co., Ltd.) was used and baked for 40 minutes at 155 ° C. under dry conditions (intermediate coating 2).
  • an acrylic resin-based colored solvent paint (trade name: Magiclon AL-2200, manufactured by Kansai Paint Co., Ltd.) was used and dried on wet at room temperature (top coating 1).
  • Product name: Clear paint Magiclon ALC-100 (manufactured by Kansai Paint Co., Ltd.) was used and baked at 155 ° C. for 40 minutes (top coating 2).
  • Examples 2 and 3> In the magnesium alloy forged wheel of Example 1, a magnesium alloy forged wheel was produced in the same manner as in Example 1 except that the contents of calcium, manganese and phosphorus contained in the chemical conversion film layer 20 were changed.
  • Example 4 As shown in Table 1, a magnesium alloy forged wheel was produced in the same manner as in Example 1 except that the epoxy resin-based primer paint used for the primer layer 20 did not contain a rust inhibitor.
  • the acrylic resin-based primer solvent paint (trade name: Magiclon ALC-2) used for forming the intermediate coating layer included in the protective layer 40a has titanium dioxide (TiO 2 ) as its component. ) And carbon.
  • the magnesium alloy forged wheel manufactured in Example 4 has a silver color due to the influence of titanium dioxide (TiO 2 ).
  • the epoxy resin-based primer used was 45.2% by weight of specially modified epoxy varnish A, 2.2% by weight of epoxy resin varnish, 1.7% by weight of melamine resin varnish and 30.1% by weight. 1 and 20.8% by weight of solvent and additives were used.
  • Example 1 In the magnesium alloy forged wheel of Example 1, an aluminum alloy forged wheel was manufactured in the same manner as in Example 1 except that an aluminum alloy forged material used as a general-purpose product was used instead of the magnesium alloy forged material 10. .
  • Reference Example 1 is a performance comparison when the above-described aluminum alloy forging material is used, the pretreatment used for forming the chemical conversion film is a silane coupling method, and the epoxy resin primer is used in the examples and This is different from the epoxy resin primer used in the comparative example.
  • Hot water resistance evaluation JIS K 6848 Ion exchange water is used and the specimen is immersed for 180 to 240 hours at a water temperature of 40 ° C. The specimen is immersed in warm water and left at room temperature for 2 to 4 hours to return to room temperature. Every 60 hours, the adhesion of the subject is inspected to determine whether it is good or bad. The adhesion evaluation was in accordance with the above initial adhesion evaluation criteria. A magnesium alloy forged wheel that satisfies the above acceptance criteria was evaluated as good (accepted). In addition, the time during which the magnesium alloy forged wheel can maintain a close contact state was measured.
  • Corrosion resistance evaluation SST test evaluation (salt spray test JIS-Z2371) Put a cross-cut reaching the material into the half of the test piece using a cutter knife, and chip the other half.
  • the sample is left in a salt spray tester at a temperature of 35 ⁇ 1 ° C. using a 5% sodium chloride aqueous solution. Take out every 120 hours, wash with water, and measure the occurrence of rust and blisters from crosscuts, edges and chipping scratches. The acceptance criterion was 3.0 mm or less.
  • said evaluation was test-evaluated with the forge board which has a component equivalent to a forge wheel.
  • the magnesium alloy forged wheel of the present invention has (1) initial adhesion evaluation (JIS K-5400), (2) warm water resistance evaluation (JIS K 6848), and (3) corrosion resistance evaluation. Both the CASS test evaluation (Copper-accelerated Acetic acid Salt Spray test) and (4) corrosion resistance evaluation SST test evaluation (salt spray test JIS-Z2371) show good results. It can be understood that the magnesium alloy forged wheels manufactured in Examples 1 to 4 have substantially the same initial adhesion, hot water resistance, and corrosion resistance as the aluminum alloy forged wheels manufactured in Reference Example 1.
  • the magnesium alloy forged wheel of the present invention has almost the same level of corrosion resistance as an aluminum alloy forged wheel employing aluminum as an alloy material.
  • the magnesium alloy forged wheel is 15 to 25% lighter than the aluminum alloy forged wheel, the technical significance when mounted on not only a racing car but also a general car is great.
  • the magnesium alloy forged wheel of the present invention is ultralight and has extremely improved corrosion resistance over a long period of time, such as warm water resistance and rust resistance.
  • the magnesium alloy forged wheel of the present invention can be applied not only to racing automobiles such as the F1 World Championship but also to general automobiles, and is extremely versatile. For this reason, the contribution to the entire automobile industry is extremely large.
  • the reduction in weight around the so-called legs of general-purpose automobiles also leads to a reduction in energy consumption, and can be expected to contribute to the energy industry and consequently to the environmental technology industry.
  • V Car 1 equipped with a magnesium alloy forged wheel 1
  • Magnesium alloy forged wheel 2 Tire 10
  • Magnesium alloy forged material 20
  • Chemical conversion coating layer 30
  • Primer layer (undercoat layer) 40a Protective layer (intercoat layer) 40b Protective layer (overcoat layer)

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Abstract

[Problem] To provide a magnesium alloy forged wheel that is extremely lightweight and that achieves improved corrosion resistance such as hot water resistance and rust prevention, and a method for manufacturing this wheel. [Solution] A corrosion-resistant magnesium alloy forged wheel provided with a chemical conversion coating layer formed on the magnesium alloy forged material, the chemical conversion coating layer containing calcium, manganese, and phosphorous, and a primer layer formed on the chemical conversion coating layer, wherein the magnesium alloy forged wheel is characterized in that the magnesium alloy forged material contains magnesium particles having an average crystal particle size of 80 μm or less on the surface, the weight ratio of the adhered amounts of calcium/manganese contained in the chemical conversion coating layer is 0.40 to 0.60, and the primer layer is formed from an epoxy-resin-based primer coating containing an epoxy resin having a weight-average molecular weight of 30,000 or less and containing 5.0 wt.% or less of a rust-preventive pigment.

Description

耐食性マグネシウム合金鍛造ホイール及びその製造方法Corrosion-resistant magnesium alloy forged wheel and manufacturing method thereof
　本発明は耐食性マグネシウム合金鍛造ホイールに関する。特に超軽量、かつ耐食性が優れたマグネシウム合金鍛造ホイール及びその製造方法に関する。さらに詳しくは、自動車用のマグネシウム合金鍛造ホイール及びその製造方法に関する。 The present invention relates to a corrosion-resistant magnesium alloy forged wheel. In particular, the present invention relates to a magnesium alloy forged wheel that is ultralight and excellent in corrosion resistance and a method for manufacturing the same. More specifically, the present invention relates to a magnesium alloy forged wheel for automobiles and a manufacturing method thereof.
　従来、タイヤやチューブ等の取付部材である車両、特に自動車のホイールとして、スチール製やアルミニウム製のものが使用されてきた。しかし近年、自動車業界においては、地球温暖化を背景に、軽量化のためにマグネシウムを含む合金製のホイール（以下「Ｍｇホイール」とも云う。）の供給が期待されている。 Conventionally, steel and aluminum wheels have been used as vehicles, particularly automobile wheels, which are mounting members such as tires and tubes. However, in recent years, the automobile industry has been expected to supply alloy wheels containing magnesium (hereinafter also referred to as “Mg wheels”) for weight reduction against the background of global warming.
　Ｍｇホイール自体は、国際自動車連盟（ＦＩＡ）が主催する自動車レースの最高峰であるＦ１世界選手権等のレース用自動車に既に採用されている。しかしながら、Ｍｇホイールは、高価でかつ耐食性が劣るなどの理由により、一般乗用車に必要とされる汎用性を有していないため、一般市場に普及されるに至っていない。 The Mg wheel itself has already been adopted in racing cars such as the F1 World Championship, which is the highest car racing sponsored by the International Automobile Federation (FIA). However, Mg wheels have not been widely used in the general market because they do not have the versatility required for general passenger cars because they are expensive and have poor corrosion resistance.
　Ｍｇホイールは、マグネシウムを含有する。マグネシウムは、その表面にアルミニウムと異なり酸化被膜を形成しやすく、塩分や腐食にきわめて弱い。このため、Ｍｇホイール表面にあらかじめ塗装処理、防錆処理等の処理をしなければならない。Ｍｇホイール表面の表面層が剥がれたら速やかに補修をしなければならない。この理由は、Ｍｇホイール表面のマグネシウムが大気に露出すると、マグネシウムが水分や酸素等と反応して腐食、錆が発生して、Ｍｇホイールの機械的強度等が急速に低下しまうからである。また、Ｍｇホイールを装着した自動車を海岸沿い等、塩分を多く含む環境下で乗用する場合には、頻繁に洗浄をしなければならない。 Mg wheel contains magnesium. Magnesium, unlike aluminum, easily forms an oxide film on its surface and is extremely vulnerable to salt and corrosion. For this reason, processing, such as a coating process and a rust prevention process, must be beforehand performed on the Mg wheel surface. If the surface layer of the Mg wheel surface peels off, it must be repaired promptly. The reason for this is that when magnesium on the surface of the Mg wheel is exposed to the atmosphere, the magnesium reacts with moisture, oxygen, etc. to cause corrosion and rust, and the mechanical strength and the like of the Mg wheel rapidly decrease. In addition, when an automobile equipped with an Mg wheel is used in a salty environment such as along the coast, it must be frequently washed.
　一方、省資源、省エネルギー等の観点から、自動車の軽量化が強く要望されると共に、マグネシウム合金の耐食性が向上したこともあって、Ｍｇホイールを一般乗用車に採用したいというニーズが大きくなっている。マグネシウムの比重はアルミニウムの比重よりも少なくとも３５％小さい。このため、自動車用ホイールの素材として、アルミニウムに代えてマグネシウムを採用した場合には、自動車用ホイール自体の重量を１５～２５％軽量化することができる。さらに、技術的に重要なことは、自動車用ホイールの重量を軽量化することは、いわゆる自動車の脚回りである「バネ下重量の軽量化」に他ならないことである。 On the other hand, from the viewpoints of resource saving and energy saving, there is a strong demand for reducing the weight of automobiles and improving the corrosion resistance of magnesium alloys, and there is a growing need to adopt Mg wheels for general passenger cars. The specific gravity of magnesium is at least 35% less than the specific gravity of aluminum. For this reason, when magnesium is used instead of aluminum as a material for an automobile wheel, the weight of the automobile wheel itself can be reduced by 15 to 25%. Furthermore, it is technically important that reducing the weight of an automobile wheel is nothing but "reducing the unsprung weight" which is the so-called leg of an automobile.
　すなわち、「バネ下重量の軽量化」は、自動車の脚回りから上の「バネ上重量の軽量化」の１０倍以上に匹敵する。自動車の脚回りである「バネ下重量の軽量化」を実現することにより、自動車発進時のスムーズな加速のみならず、走行時における路面の凹凸に対する自動車車体のレスポンスの向上にダイレクトに繋がる。その結果、自動車走行時のハンドルのブレが減少するなど運転性能の向上にも大きく繋がる。このようなニーズを受けて、マグネシウム合金を素材として採用し、一般的な皮膜処理を行って、製造されたマグネシウムホイールが提案されている（例えば、非特許文献１）。 That is, “lightening the unsprung weight” is equivalent to more than 10 times the “reducing the weight of the sprung” above the leg of the car. By realizing “reducing the unsprung weight” that is the leg of an automobile, not only smooth acceleration at the start of the automobile, but also direct improvement in the response of the automobile body to road surface irregularities during driving. As a result, the driving performance is greatly improved, for example, the blurring of the steering wheel when the vehicle is running is reduced. In response to such needs, a magnesium wheel manufactured by employing a magnesium alloy as a raw material and performing a general film treatment has been proposed (for example, Non-Patent Document 1).
　しかしながら、この改善されたマグネシウムホイールと従来のスチールやアルミニウム等によるホイールとを比べてみると、Ｍｇホイールは軽量であることにおいて優れているが、耐食性（例えば、塩水噴霧試験）は実用的にみて十分でなく、アルミニウムホイールに比べて極端に劣っている。 However, when this improved magnesium wheel is compared with a conventional wheel made of steel, aluminum, etc., the Mg wheel is superior in being lightweight, but the corrosion resistance (for example, salt spray test) is practically seen. Not enough and extremely inferior to aluminum wheels.
　そこで、Ｍｇ合金ホイールの耐食性を向上させるために、Ｍｇ合金表面に種々の耐食性塗膜を形成する方法が提案されており、その中にはカルシウムイオン、マンガンイオン及びリン酸イオンを含む処理液によりＭｇ合金ホイール素材上に化成皮膜を形成して、耐食性、防錆性、塗装密着性を向上させる方法がある（例えば、特許文献１～４）。しかしながら、このように塗装したＭｇホイールにおいて、走行中に跳ね上げられた飛び石等の衝突によって塗膜表面がキズつきやすく、そのキズが素材にまで達してその部分から腐食して孔食を起こしやすいという欠陥を有しており、その改良が強く望まれている。なお、本件特許出願人は、上記文献公知発明が記載された刊行物として、以下の刊行物を提示する。 Therefore, in order to improve the corrosion resistance of the Mg alloy wheel, various methods for forming a corrosion-resistant coating film on the surface of the Mg alloy have been proposed. Among them, a treatment liquid containing calcium ions, manganese ions and phosphate ions is used. There is a method of improving the corrosion resistance, rust resistance, and paint adhesion by forming a chemical conversion film on the Mg alloy wheel material (for example, Patent Documents 1 to 4). However, in the Mg wheel coated in this way, the surface of the coating film is easily scratched by the collision of the stepping stones and the like that are thrown up while traveling, and the scratch reaches the material and easily corrodes from the part to cause pitting corrosion. The improvement is strongly desired. In addition, this patent applicant presents the following publications as publications in which the above-mentioned literature known invention is described.
特開平１１－１３１２５５号公報JP-A-11-131255 特開２０００－　９６２５５号公報JP 2000-96255 A 特開２００３－２８６５８２号公報JP 2003-286582 A 特開２００５－２８１７１７号公報JP 2005-281717 A 特開２００３－　８２２７７号公報JP 2003-82277 A
　本発明は、かかる技術的事情に鑑みなされたものであって、従来のマグネシウム合金ホイールにおける問題を解決し、超軽量であり、耐温水性、防錆性等の長時間にわたる耐食性を向上させたマグネシウム合金鍛造ホイール及びその製造方法を提供することを課題とする。 The present invention has been made in view of such technical circumstances, and has solved problems in conventional magnesium alloy wheels, is ultralight, and has improved corrosion resistance over a long period of time, such as warm water resistance and rust resistance. It is an object to provide a magnesium alloy forged wheel and a method for manufacturing the same.
　本件発明者は、鋭意技術的検討を行った結果、マグネシウム合金鍛造ホイールの部材として、マグネシウム合金鍛造素材上に形成されたカルシウムとマンガンとリンとを含む化成皮膜層とその化成皮膜層上に形成されたプライマー層とを備えることにより、超軽量であり、耐温水性、防錆性等の長時間にわたる耐食性を向上できることを見出し、本発明を完成するに至った。より具体的には、本発明は以下の技術的事項から構成される。 As a result of earnest technical examination, the present inventor has formed a conversion coating layer containing calcium, manganese, and phosphorus formed on a magnesium alloy forging material and a conversion coating layer as a member of a magnesium alloy forging wheel. It was found that it was ultra-lightweight by being provided with the prepared primer layer, and corrosion resistance over a long period of time such as warm water resistance and rust resistance could be improved, and the present invention was completed. More specifically, the present invention comprises the following technical matters.
　（１）マグネシウム合金鍛造素材上に形成されたカルシウムとマンガンとリンとを含む化成皮膜層と、前記化成皮膜層上に形成されたプライマー層とを備えた耐食性マグネシウム合金鍛造ホイールであって、前記マグネシウム合金鍛造素材は、その表面に平均結晶粒子径が８０μｍ以下であるマグネシウム粒子を含有し、
　前記化成皮膜層に含まれるカルシウム／マンガンの付着量重量比は０．４０～０．６０であり、
　前記プライマー層が重量平均分子量３０，０００以下のエポキシ樹脂を含み、且つ防錆顔料５．０重量％以下を含むエポキシ樹脂系プライマー塗料から形成されたことを特徴とする耐食性マグネシウム合金鍛造ホイール。 (1) A corrosion-resistant magnesium alloy forged wheel comprising a chemical conversion film layer containing calcium, manganese and phosphorus formed on a magnesium alloy forging material, and a primer layer formed on the chemical conversion film layer, The magnesium alloy forging material contains magnesium particles having an average crystal particle diameter of 80 μm or less on the surface thereof,
The weight ratio of calcium / manganese adhesion contained in the chemical conversion coating layer is 0.40 to 0.60,
A corrosion-resistant magnesium alloy forged wheel, wherein the primer layer comprises an epoxy resin-based primer paint containing an epoxy resin having a weight average molecular weight of 30,000 or less and containing an antirust pigment of 5.0 wt% or less.
　（２）前記化成皮膜層はカルシウムを１～１５０ｍｇ／ｍ２、マンガンを２～３８０ｍｇ／ｍ２、リンを１～６００ｍｇ／ｍ２含むことを特徴とする（１）に記載の耐食性マグネシウム合金鍛造ホイール。 (2) the conversion coating layer is calcium 1 ~ 150mg / m 2, manganese 2 ~ 380 mg / m 2, characterized in that the phosphorus containing 1 ~ 600mg / m 2 (1 ) corrosion resistance of magnesium alloy forged according wheel.
　（３）前記エポキシ樹脂系プライマー層に含まれるエポキシ樹脂が重量平均分子量９，０００～２０，０００であることを特徴とする（１）又は（２）に記載の耐食性マグネシウム合金鍛造ホイール。 (3) The corrosion-resistant magnesium alloy forged wheel according to (1) or (2), wherein the epoxy resin contained in the epoxy resin-based primer layer has a weight average molecular weight of 9,000 to 20,000.
　（４）前記プライマー層上に保護層と備えたことを特徴とする（１）～（３）のいずれか１に記載の耐食性マグネシウム合金鍛造ホイール。 (4) The corrosion-resistant magnesium alloy forged wheel according to any one of (1) to (3), wherein a protective layer is provided on the primer layer.
　（５）表面の平均結晶粒子径が８０μｍ以下のマグネシウム合金鍛造ホイール素材の該表面をカルシウムイオンとマンガンイオンとリン酸イオンとを含む化成処理液と接触させて該マグネシウム合金鍛造ホイール素材上にカルシウムとマンガンとリンとを含み、且つカルシウム／マンガンの付着量重量比が０．４０～０．６０の化成皮膜を形成する工程と、前記化成皮膜上に重量平均分子量が３０，０００以下のエポキシ樹脂を含み、且つ防錆顔料５．０重量％以下を含むエポキシ樹脂系プライマー塗料を塗装してプライマー層を形成する工程と、を含むことを特徴とする耐食性マグネシウム合金鍛造ホイールの製造方法。 (5) The surface of the magnesium alloy forged wheel material having an average crystal particle size of 80 μm or less is brought into contact with a chemical conversion treatment solution containing calcium ions, manganese ions and phosphate ions, and calcium is deposited on the magnesium alloy forged wheel material. And a step of forming a chemical conversion film having a calcium / manganese adhesion weight ratio of 0.40 to 0.60, and an epoxy resin having a weight average molecular weight of 30,000 or less on the chemical conversion film And a step of applying an epoxy resin-based primer paint containing 5.0 wt% or less of an anticorrosive pigment to form a primer layer, and a method for producing a corrosion-resistant magnesium alloy forged wheel.
　本発明によれば、超軽量であり、耐温水性、防錆性等の長時間にわたる耐食性に優れたマグネシウム合金鍛造ホイールが提供される。 According to the present invention, there is provided a magnesium alloy forged wheel that is ultralight and has excellent corrosion resistance over a long period of time, such as warm water resistance and rust resistance.
マグネシウム合金鍛造ホイールを装着した自動車の脚回りを示したモデル図である。It is the model figure which showed the leg periphery of the motor vehicle equipped with the magnesium alloy forge wheel. マグネシウム合金鍛造ホイールの断面構造を示した概略図である。It is the schematic which showed the cross-section of the magnesium alloy forge wheel. マグネシウム合金鍛造ホイールの断面構造の拡大モデル図である。It is an expansion model figure of the section structure of a magnesium alloy forge wheel. マグネシウム合金鍛造ホイールのスポーク部におけるマグネシウムの平均結晶粒径を示したＩＰＦマップである。It is an IPF map which showed the average grain size of magnesium in the spoke part of a magnesium alloy forge wheel. 保護層を備えたマグネシウム合金鍛造ホイールの断面構造の拡大モデル図である。It is an enlarged model figure of the section structure of a magnesium alloy forge wheel provided with a protective layer.
　以下、本発明の実施形態を適宜図面に基づいて説明する。まず、図１は、マグネシウム合金鍛造ホイールを装着した自動車の脚回りを示したモデル図である。マグネシウム合金鍛造ホイール１のＸ軸方向の周囲には、タイヤ２が装着されている。マグネシウム合金鍛造ホイール１とタイヤ２は、これらを一組として、自動車Ｖが備えている前後左右の４箇所に装着される。 Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. First, FIG. 1 is a model diagram showing the leg circumference of an automobile equipped with a magnesium alloy forged wheel. A tire 2 is mounted around the magnesium alloy forged wheel 1 in the X-axis direction. The magnesium alloy forged wheel 1 and the tire 2 are mounted at four locations on the front, rear, left and right sides of the automobile V as a set.
　図２は、上記マグネシウム合金鍛造ホイールの断面構造を示した概略図である。マグネシウム合金鍛造ホイール１は、マグネシウム合金鍛造素材１０上に化成皮膜層２０が積層され、さらに化成皮膜層２０上にプライマー層３０が積層されている。マグネシウム合金鍛造素材１０、化成皮膜層２０及びプライマー層３０は、相互に密着された状態で一体となって、マグネシウム合金鍛造ホイール１を形成している。以下、マグネシウム合金鍛造ホイール１について詳細に説明する。 FIG. 2 is a schematic view showing a cross-sectional structure of the magnesium alloy forged wheel. In the magnesium alloy forged wheel 1, a chemical film layer 20 is laminated on the magnesium alloy forged material 10, and a primer layer 30 is further laminated on the chemical film layer 20. The magnesium alloy forging material 10, the chemical conversion film layer 20, and the primer layer 30 are integrated together to form the magnesium alloy forged wheel 1 while being in close contact with each other. Hereinafter, the magnesium alloy forged wheel 1 will be described in detail.
＜マグネシウム合金鍛造ホイール＞
　本発明のマグネシウム合金鍛造ホイールは、乗用車、オートバイ、バス、トラック、ワゴン車等の自動車、及び自転車等の車両に装着されるものである。特に自動車用鍛造ホイールとして採用される場合に必要となるニーズをすべて満たす、超軽量であり、耐温水性、防錆性等の長時間にわたる耐食性に優れたマグネシウム合金鍛造ホイールである。 <Magnesium alloy forged wheel>
The magnesium alloy forged wheel of the present invention is attached to automobiles such as passenger cars, motorcycles, buses, trucks, wagon cars, and vehicles such as bicycles. In particular, it is a magnesium alloy forged wheel that meets all the needs required when it is used as a forged wheel for automobiles, is ultra-lightweight, and has excellent corrosion resistance over a long period of time, such as warm water resistance and rust resistance.
　図３は、マグネシウム合金鍛造ホイール１の断面構造の拡大モデル図である。図３に示すように、本発明のマグネシウム合金鍛造ホイール１は、マグネシウム合金鍛造素材１０上に形成されたカルシウムとマンガンとリンとを含む化成皮膜層２０とこの化成皮膜層２０上に形成されたプライマー層３０とを備えている。以下、マグネシウム合金鍛造ホイール１が備えている各層について説明する。 FIG. 3 is an enlarged model view of the cross-sectional structure of the magnesium alloy forged wheel 1. As shown in FIG. 3, the magnesium alloy forged wheel 1 of the present invention is formed on the conversion coating layer 20 containing calcium, manganese and phosphorus formed on the magnesium alloy forging material 10 and on this conversion coating layer 20. And a primer layer 30. Hereinafter, each layer provided in the magnesium alloy forged wheel 1 will be described.
（マグネシウム合金鍛造ホイール素材１０）
　マグネシウム合金鍛造ホイール素材１０の材料（ビレット）として、使用されるマグネシウム合金は、マグネシウムを主成分とする合金である。具体的にマグネシウム合金は、マグネシウムを９０重量％以上とし、その他の成分として、アルミニウム（Ａｌ）、亜鉛（Ｚｎ）、マンガン（Ｍｎ）等を少量、好ましくは１０重量％以下の量で含有することもある合金が含まれる。 (Magnesium alloy forged wheel material 10)
The magnesium alloy used as the material (billet) of the magnesium alloy forged wheel material 10 is an alloy containing magnesium as a main component. Specifically, the magnesium alloy contains magnesium in an amount of 90% by weight or more, and contains other components such as aluminum (Al), zinc (Zn), manganese (Mn) in a small amount, preferably 10% by weight or less. Some alloys are also included.
　２成分系のＭｇ－Ｚｎ合金、３成分系のＭｇ－Ａｌ－Ｚｎ合金、４成分系のＭｇ－Ａｌ－Ｚｎ－Ｍｎ合金等のマグネシウム合金であってもよい。さらに、上記マグネシウム合金は、不純物量（例えば０．０１重量％以下）のその他の元素、例えばＮｉ、Ｆｅ、Ｃｕ、Ｓｉ等を含んでもよい。 A magnesium alloy such as a two-component Mg—Zn alloy, a three-component Mg—Al—Zn alloy, or a four-component Mg—Al—Zn—Mn alloy may also be used. Furthermore, the magnesium alloy may contain other elements such as Ni, Fe, Cu, Si, etc. in the amount of impurities (for example, 0.01% by weight or less).
　マグネシウム合金鍛造ホイール素材１０の材料（ビレット）は、特に１方向若しくは２方向鍛造方式で成形される。マグネシウム合金鍛造ホイール１を成形する際の鍛錬比は、１～１５であり、好ましくは、３～１０、更に好ましくは、４～７である。なお、マグネシウム合金鍛造ホイール素材は、マグネシウム合金鍛造ホイール素材１０の材料（ビレット）を３００～４００℃に加熱しながら、３，５００～５，０００ｋｇ／ｃｍ２の圧力をかけて、ホイール１次構造～３次構造を形成する工程、及びスピニング工程を経て製造される。 The material (billet) of the magnesium alloy forged wheel material 10 is particularly formed by a one-way or two-way forging method. The forging ratio when forming the magnesium alloy forged wheel 1 is 1 to 15, preferably 3 to 10, and more preferably 4 to 7. The magnesium alloy forged wheel material is the primary structure of the wheel by applying a pressure of 3,500 to 5,000 kg / cm 2 while heating the material (billet) of the magnesium alloy forged wheel material 10 to 300 to 400 ° C. Manufactured through a process of forming a tertiary structure and a spinning process.
　マグネシウム合金鍛造ホイール素材１０の材料（ビレット）は、その平均結晶粒子径が３００μｍ程度であるマグネシウム粒子を含んでいる。これを鍛造することで１方向鍛造では、平均結晶粒子径が３０～８０μｍに、２方向鍛造では、平均結晶粒子径が１０～３０μｍに微粒子化できる。平均結晶粒子径が１０μｍ未満であると、マグネシウム粒子からなる結晶がきわめて密となり、空気孔が形成されないためマグネシウム合金鍛造ホイールの強度は向上するが、上層の化成皮膜層、プライマー層との密着性が得られ難くなるため好ましくない。また、平均結晶粒子径が８０μｍを超えると、マグネシウム粒子の平均結晶粒子を制御することが容易となるが、マグネシウム合金鍛造ホイール素材１０の強度が低下するため好ましくない。 The material (billet) of the magnesium alloy forged wheel material 10 includes magnesium particles having an average crystal particle diameter of about 300 μm. By forging this, the average crystal particle diameter can be reduced to 30 to 80 μm in the unidirectional forging, and the average crystal particle diameter can be reduced to 10 to 30 μm in the two-way forging. If the average crystal particle diameter is less than 10 μm, the magnesium particles become extremely dense and air holes are not formed, so the strength of the magnesium alloy forged wheel is improved, but the adhesion to the upper chemical conversion coating layer and primer layer is improved. Is not preferred because it is difficult to obtain. Further, if the average crystal particle diameter exceeds 80 μm, it becomes easy to control the average crystal particles of the magnesium particles, but it is not preferable because the strength of the magnesium alloy forged wheel material 10 is lowered.
　図４は、２方向鍛造方式で作製されたマグネシウム合金鍛造ホイール１のスポーク部におけるマグネシウムの平均結晶粒径を示したＩＰＦマップである。図４によれば、マグネシウム合金鍛造ホイール１のスポーク部におけるマグネシウムの平均結晶粒径は、１２μｍであることが理解できる。 FIG. 4 is an IPF map showing the average crystal grain size of magnesium in the spoke part of the magnesium alloy forged wheel 1 produced by the two-way forging method. According to FIG. 4, it can be understood that the average crystal grain size of magnesium in the spoke portion of the magnesium alloy forged wheel 1 is 12 μm.
　すなわち、マグネシウム合金鍛造ホイール１は、マグネシウム合金鍛造ホイール素材１０の材料（ビレット）を構成するマグネシウム粒子として、特定の平均結晶粒子半径を有するものを採択することにより、均質でかつ安定的な金属組織を形成させて、超軽量であり、マグネシウム合金鍛造ホイールの提供を実現している。そして、後述するカルシウム、マンガン及びリンを含み且つカルシウム／マンガン重量比が０．６以下の化成皮膜層を採用することにより、上記の強度がきわめて優れたマグネシウム合金鍛造ホイールを製造することができる。 That is, in the magnesium alloy forged wheel 1, a homogeneous and stable metal structure is adopted by adopting magnesium particles having a specific average crystal particle radius as the magnesium particles constituting the material (billet) of the magnesium alloy forged wheel material 10. The ultra-lightweight, forged magnesium alloy wheel is realized. And the magnesium alloy forge wheel which was excellent in said intensity | strength can be manufactured by employ | adopting the chemical conversion film layer which contains calcium, manganese, and phosphorus which are mentioned later, and a calcium / manganese weight ratio is 0.6 or less.
（化成皮膜層２０）
　本発明のマグネシウム合金鍛造ホイール１は、マグネシウム合金鍛造ホイール素材１０上に化成皮膜層２０を備えている。化成皮膜層２０はカルシウムとマンガンとリンとを含んでいる。化成皮膜層２０に含まれるカルシウムとマンガンとリンは、マグネシウム合金鍛造ホイール素材１０の表面に存在するマグネシウム粒子と相互作用の結果、安定した結晶構造を形成する。この結果、マグネシウム合金鍛造ホイール素材１０と化成皮膜層２０とは固定化される。 (Chemical conversion film layer 20)
The magnesium alloy forged wheel 1 of the present invention includes a chemical conversion coating layer 20 on a magnesium alloy forged wheel material 10. The chemical conversion film layer 20 contains calcium, manganese, and phosphorus. Calcium, manganese and phosphorus contained in the chemical conversion coating layer 20 form a stable crystal structure as a result of interaction with magnesium particles present on the surface of the magnesium alloy forged wheel material 10. As a result, the magnesium alloy forged wheel material 10 and the chemical conversion film layer 20 are fixed.
　化成皮膜層２０に含まれるカルシウム、マンガン及びリンの含有量は、それぞれカルシウムが１～１５０ｍｇ／ｍ２、好ましくは１０～１１０ｍｇ／ｍ２であり、マンガンが２～３８０ｍｇ／ｍ２、好ましくは２０～２８０ｍｇ／ｍ２であり、リンが１．０～６００ｍｇ／ｍ２、好ましくは１０～４００ｍｇ／ｍ２であることが好ましい。化成皮膜層２０に含まれるカルシウム、マンガン及びリンの含有量が上記範囲内であると、化成皮膜層２０内において、カルシウム、マンガン及びリンの３成分が安定化し、これらの３成分とマグネシウム合金鍛造ホイール素材１０の材料（ビレット）を構成するマグネシウム粒子とにより安定な結晶構造を形成することができるため好ましい。 Calcium contained in the chemical conversion coating layer 20, the content of manganese and phosphorus, calcium each 1 ~ 150mg / m 2, preferably 10 ~ 110mg / m 2, manganese 2 ~ 380mg / m 2, preferably 20 It is preferably ˜280 mg / m 2 and phosphorus is 1.0 to 600 mg / m 2 , preferably 10 to 400 mg / m 2 . If the content of calcium, manganese and phosphorus contained in the chemical conversion film layer 20 is within the above range, the three components of calcium, manganese and phosphorus are stabilized in the chemical conversion film layer 20, and these three components and magnesium alloy forging This is preferable because a stable crystal structure can be formed with the magnesium particles constituting the material (billet) of the wheel material 10.
　なお、化成皮膜層２０に含まれるカルシウムとマンガンとリンの含有量は、蛍光Ｘ線（ＸＲＦ）分析法により測定した。具体的には、蛍光Ｘ線（ＸＲＦ）分析法による検量線法を用い、含有量が既知の標準試料の蛍光Ｘ線（ＸＲＦ）強度を測定し、この標準試料の含有量と蛍光Ｘ線（ＸＲＦ）の測定強度により検量線を作成した。化成皮膜層２０の未知元素資料の蛍光Ｘ線強度を測定し、検量線を利用して付着量を求め、これを化成皮膜層２０に含まれるカルシウム、マンガン及びリンの含有量とした。 The contents of calcium, manganese and phosphorus contained in the chemical conversion film layer 20 were measured by a fluorescent X-ray (XRF) analysis method. Specifically, using a calibration curve method based on a fluorescent X-ray (XRF) analysis method, the fluorescent X-ray (XRF) intensity of a standard sample with a known content is measured, and the content of this standard sample and the fluorescent X-ray ( A calibration curve was prepared based on the measured intensity of (XRF). The fluorescence X-ray intensity of the unknown element material of the chemical conversion film layer 20 was measured, and the amount of adhesion was determined using a calibration curve. This was used as the content of calcium, manganese and phosphorus contained in the chemical conversion film layer 20.
　化成皮膜層２０に含まれるカルシウムとマンガンの中でマグネシウム合金鍛造ホイール素材１０の表面に付着している量は、重量比（カルシウム／マンガン）で０．４０～０．６０であることが好ましく、さらに好ましくは、０．４５～０．５５であることが好ましい。重量比（カルシウム／マンガン）が０．４０以上であるとマグネシウム合金鍛造ホイール素材１０の材料（ビレット）を構成するマグネシウム粒子と安定な結晶構造を形成することができるため好ましく、０．６０以下であるとマグネシウム合金鍛造ホイール１の防錆性が向上するため好ましい。 The amount of calcium and manganese contained in the chemical conversion coating layer 20 that adheres to the surface of the magnesium alloy forged wheel material 10 is preferably 0.40 to 0.60 in weight ratio (calcium / manganese). More preferably, it is 0.45 to 0.55. A weight ratio (calcium / manganese) of 0.40 or more is preferable because a stable crystal structure can be formed with magnesium particles constituting the material (billet) of the magnesium alloy forged wheel material 10, and is preferably 0.60 or less. It is preferable because the rust resistance of the magnesium alloy forged wheel 1 is improved.
　化成皮膜層２０に含まれるカルシウムとマンガン及びリンは、マグネシウム合金鍛造ホイール１を構成するプライマー層３０に含まれているエポキシ樹脂成分と化学的に結合することできる。化成皮膜層２０の膜厚は、特に制限されるものではないが、１．０～３．０μｍであることが好ましい。 Calcium, manganese and phosphorus contained in the chemical conversion film layer 20 can be chemically bonded to the epoxy resin component contained in the primer layer 30 constituting the magnesium alloy forged wheel 1. The film thickness of the chemical conversion film layer 20 is not particularly limited, but is preferably 1.0 to 3.0 μm.
（プライマー層３０）
　本発明のマグネシウム合金鍛造ホイール１は、上記化成皮膜層２０上にプライマー層３０を備えている。プライマー層３０は、エポキシ樹脂系プライマー塗料を上記化成皮膜層２０上に塗布して形成された層である。プライマー層３０に含まれるエポキシ樹脂としては、重量平均分子量が３０，０００以下、好ましくは９，０００～１０，０００のエポキシ樹脂及びこれらの誘導体が含まれる。プライマー層３０に含まれるエポキシ樹脂としては、特に重量平均分子量が１０，０００程度のエポキシ樹脂が好ましい。 (Primer layer 30)
The magnesium alloy forged wheel 1 of the present invention includes a primer layer 30 on the chemical conversion film layer 20. The primer layer 30 is a layer formed by applying an epoxy resin-based primer paint on the chemical conversion film layer 20. The epoxy resin contained in the primer layer 30 includes an epoxy resin having a weight average molecular weight of 30,000 or less, preferably 9,000 to 10,000, and derivatives thereof. As the epoxy resin contained in the primer layer 30, an epoxy resin having a weight average molecular weight of about 10,000 is particularly preferable.
　プライマー層３０を構成するエポキシ樹脂の分子量を緻密に制御することにより、あらゆる自動車車種、用途に応じて造形される複雑な形状を有するマグネシウム合金鍛造ホイール素材１０の細部にも、均一なプライマー層３０を形成することができる。 By precisely controlling the molecular weight of the epoxy resin constituting the primer layer 30, the uniform primer layer 30 can be applied even to the details of the magnesium alloy forged wheel material 10 having a complicated shape that is shaped according to any vehicle model and application. Can be formed.
　プライマー層３０に含まれるエポキシ樹脂としては、例えば下記一般式で表されるグリシジル基を含むエポキシ樹脂を挙げることができる。 Examples of the epoxy resin contained in the primer layer 30 include an epoxy resin containing a glycidyl group represented by the following general formula.
Figure JPOXMLDOC01-appb-C000001
 （上記一般式中、Ｚは水素原子、メチル基又はエチル基を示す。）
Figure JPOXMLDOC01-appb-C000001
 (In the above general formula, Z represents a hydrogen atom, a methyl group or an ethyl group.)
　プライマー層３０に含まれるエポキシ樹脂は、上記一般式により示される置換又は非置換のグリシジル基を分子内に少なくとも１個有する化合物である。エポキシ樹脂は、例えば、グリシジルエーテル型、グリシジルエステル型、グリシジルアミン型、グリシジルイミン型を採ることができる。 The epoxy resin contained in the primer layer 30 is a compound having at least one substituted or unsubstituted glycidyl group represented by the above general formula in the molecule. The epoxy resin can take, for example, a glycidyl ether type, a glycidyl ester type, a glycidyl amine type, and a glycidyl imine type.
　具体的には、ビスフェノールＡのジグリシジルエーテル、ビスフェノールＦのジグリシジルエーテル、フェノールノボラックのエポキシ樹脂、ビスフェノール類のアルキレンオキシド付加物のジグリシジルエーテル等を挙げることができる。具体例として、特殊変性エポキシ樹脂系ワニスを主剤とし、重量平均分子量１０，０００～２０，０００程度に高分子化し、メラミン樹脂系ワニスを添加して架橋密度を上げたエポキシ樹脂系プライマー塗料を用いることができる。具体的には、エポキシ樹脂系プライマー塗料（商品名：ＢＳプライマー、大日本塗料株式会社製）を用いることができる。 Specific examples include diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, epoxy resin of phenol novolac, diglycidyl ether of an alkylene oxide adduct of bisphenols, and the like. As a specific example, an epoxy resin-based primer coating having a specially modified epoxy resin-based varnish as a main ingredient, polymerized to a weight average molecular weight of about 10,000 to 20,000, and added with a melamine resin-based varnish to increase the crosslinking density is used. be able to. Specifically, an epoxy resin primer paint (trade name: BS primer, manufactured by Dainippon Paint Co., Ltd.) can be used.
　プライマー層３０は、防錆顔料を含んでいないか、又は防錆顔料を５．０重量％以下含むことを特徴とする。マグネシウム合金鍛造ホイール１は、超軽量であり、耐温水性、防錆性等の長時間にわたる耐食性に優れたものであるが、マグネシウム合金鍛造ホイール素材１０の材料（ビレット）を構成するマグネシウム合金粒子及び化成皮膜層を備えていることにより、特に防錆顔料を含有していなくても、十分な耐温水性、防錆性等の長時間にわたる耐食性を実現することができる。 The primer layer 30 is characterized by not containing a rust preventive pigment or containing 5.0 wt% or less of a rust preventive pigment. The magnesium alloy forged wheel 1 is ultralight and has excellent corrosion resistance over a long period of time, such as warm water resistance and rust resistance, but the magnesium alloy particles constituting the material (billet) of the magnesium alloy forged wheel material 10 And by providing the chemical conversion film layer, corrosion resistance over a long period of time, such as sufficient hot water resistance and rust resistance, can be realized even if no rust preventive pigment is contained.
　プライマー層３０は、ポリアミド硬化剤を含んでいてもよい。ポリアミド硬化剤として、第１級アミノ基又は第２級アミノ基を１分子あたり、平均１．７個以上を有するポリアミドを採用することができる。具体的には、リノレイン酸、オレイン酸、リノール酸、エライジン酸、リシノレイン酸等の分子中に不飽和結合を有する高級脂肪酸を重合して得られるダイマー酸、トリマー酸等の重合脂肪酸とポリアミン、特に脂肪酸ポリアミンとの縮合生成物を例示することができる。以下に、リノレイン酸のダイマー酸を使用した場合のポリアミドを示す。 The primer layer 30 may contain a polyamide curing agent. As the polyamide curing agent, a polyamide having an average of 1.7 or more primary amino groups or secondary amino groups per molecule can be employed. Specifically, polymerized fatty acids such as linoleic acid, oleic acid, linoleic acid, elaidic acid, ricinoleic acid and the like, which are obtained by polymerizing a higher fatty acid having an unsaturated bond, such as dimer acid and trimer acid, and polyamines, in particular Examples thereof include condensation products with fatty acid polyamines. The following shows polyamides using linolenic acid dimer acid.
Figure JPOXMLDOC01-appb-C000002
 （上記化学式中、Ｒ１及びＲ２はそれぞれ同一であっても異なっていてもよく、ポリアミンの残基である。）
Figure JPOXMLDOC01-appb-C000002
 (In the above chemical formula, R 1 and R 2 may be the same or different and are polyamine residues.)
　さらに、プライマー層３０は、硬化助剤及び／又は硬化促進剤を含んでいてもよい。硬化助剤としては、例えば、ＢＦ３－アミン錯体、無水ヘキサハイドロフタル酸、ジシアンジアミド、２－エチル－４－メチルイミダゾール等のイミダゾール類等を例示することができる。硬化促進剤としては、トリエチルテトラミン、変性脂肪酸ポリアミン、変性芳香族ポリアミン等を例示することができる。 Furthermore, the primer layer 30 may contain a curing aid and / or a curing accelerator. Examples of curing aids include BF 3 -amine complexes, hexahydrophthalic anhydride, dicyandiamide, imidazoles such as 2-ethyl-4-methylimidazole, and the like. Examples of the curing accelerator include triethyltetramine, modified fatty acid polyamine, modified aromatic polyamine and the like.
　また、プライマー層３０は、エポキシ樹脂の架橋度を調整するために、連鎖延長剤及び／又は架橋剤を含んでいてもよい。連鎖延長剤は、エポキシ樹脂の架橋度を調整することができるものであれば、特に制限されるものではないが、アゼライン酸、フマル酸等の二塩基酸、１，６－ヘキサンジジオール、１，８―オクタンジオール等のジメルカプタン類、無水マレイン酸、無水コハク酸、無水フタル酸、無水ヘキサハイドロフタル酸等の酸無水物、ジイソシアネート類、脂肪族アミン類、脂肪族ポリアミン類、脂環式ジアミン、脂環式ポリアミン類、複素環式ジアミン、複素環式ポリアミン類、炭素数１～１２の脂肪族ジハロゲン化合物、炭素数６～１８のジヒドロキシ芳香族化合物等を例示することができる。 Further, the primer layer 30 may contain a chain extender and / or a crosslinking agent in order to adjust the degree of crosslinking of the epoxy resin. The chain extender is not particularly limited as long as it can adjust the degree of crosslinking of the epoxy resin, but is not limited to dibasic acids such as azelaic acid and fumaric acid, 1,6-hexanedidiol, , 8-octanediol and other dimercaptans, maleic anhydride, succinic anhydride, phthalic anhydride, hexahydrophthalic anhydride and other acid anhydrides, diisocyanates, aliphatic amines, aliphatic polyamines, alicyclic Examples include diamines, alicyclic polyamines, heterocyclic diamines, heterocyclic polyamines, aliphatic dihalogen compounds having 1 to 12 carbon atoms, and dihydroxy aromatic compounds having 6 to 18 carbon atoms.
　プライマー層３０は、必要に応じて、無機顔料を含んでいてもよい。無機顔料としては、プライマー層３０に必要とされる性能を低下させるものでなければ特に制限されるものではないが、酸化チタン、亜鉛華、酸化鉄、フタロシアニンブルー、ベンジジンイエロー等の着色顔料、石英粉、酸化アルミナ、沈降性硫酸バリウム等の体質顔料、ステンレス粉、亜鉛粉、アルミニウム粉、雲母等の金属粉、酸化亜鉛、リン酸亜鉛、鉛、トリポリリン酸等の防錆顔料を例示することができる。 The primer layer 30 may contain an inorganic pigment as necessary. The inorganic pigment is not particularly limited as long as it does not lower the performance required for the primer layer 30, but is a color pigment such as titanium oxide, zinc white, iron oxide, phthalocyanine blue, and benzidine yellow, quartz Examples include extender pigments such as powder, alumina oxide and precipitated barium sulfate, metal powders such as stainless powder, zinc powder, aluminum powder and mica, and rust preventive pigments such as zinc oxide, zinc phosphate, lead and tripolyphosphoric acid. it can.
　プライマー層３０は、プライマー層の原料となるプライマー塗料を化成皮膜層２０上に塗装後、乾燥して得られるものである。上記プライマー塗料に含まれる溶剤としては、適切な粘度を有するプライマー塗料を得ることができるものであれば、特に制限されるものではないが、トルエン、キシレン等の炭化水素系溶剤、酢酸ブチル等のエステル系溶剤、メチルエチルケトン、シクロヘキサン、イソホロン等のケトン系溶剤、メタノール、エタノール、ブタノール等のアルコール系溶剤等を挙げることができる。 The primer layer 30 is obtained by applying a primer paint as a raw material for the primer layer on the chemical conversion film layer 20 and then drying it. The solvent contained in the primer paint is not particularly limited as long as a primer paint having an appropriate viscosity can be obtained, but hydrocarbon solvents such as toluene and xylene, butyl acetate and the like. Examples thereof include ester solvents, ketone solvents such as methyl ethyl ketone, cyclohexane and isophorone, and alcohol solvents such as methanol, ethanol and butanol.
　プライマー層３０の膜厚は、特に制限されるものではないが１０～３０μｍであることが好ましい。プライマー層３０の膜厚が１０μｍ未満であると耐温水性、防錆性等の長時間にわたる耐食性を向上することができないため好ましくなく、３０μｍを超えるとマグネシウム合金鍛造ホイール１の超軽量化及び塗膜の密着性を向上することができないため好ましくない。 The film thickness of the primer layer 30 is not particularly limited, but is preferably 10 to 30 μm. If the thickness of the primer layer 30 is less than 10 μm, corrosion resistance over a long period of time such as warm water resistance and rust resistance cannot be improved, and if it exceeds 30 μm, the magnesium alloy forged wheel 1 is reduced in weight and coated. This is not preferable because the adhesion of the film cannot be improved.
（保護層４０）
　本発明のマグネシウム合金鍛造ホイール１は、マグネシウム合金鍛造素材１０上に形成されたカルシウムとマンガンとリンとを含む化成皮膜層２０と、化成皮膜層２０上に形成されたプライマー層３０を基本層Ａとし、さらにプライマー層３０上に保護層４０を備えていてもよい。図５に、保護層４０を備えたマグネシウム合金鍛造ホイール１の断面構造の拡大モデル図を示した。図５に示されたマグネシウム合金鍛造ホイール１は保護層４０として、中塗り層４０ａ及び上塗り塗料層４０ｂを備えている。 (Protective layer 40)
The magnesium alloy forged wheel 1 according to the present invention includes a conversion coating layer 20 containing calcium, manganese, and phosphorus formed on a magnesium alloy forging material 10 and a primer layer 30 formed on the conversion coating layer 20 as a basic layer A. In addition, a protective layer 40 may be provided on the primer layer 30. In FIG. 5, the enlarged model figure of the cross-section of the magnesium alloy forge wheel 1 provided with the protective layer 40 was shown. The magnesium alloy forged wheel 1 shown in FIG. 5 includes an intermediate coating layer 40 a and a top coating layer 40 b as the protective layer 40.
　中塗り層４０ａは、マグネシウム合金鍛造ホイール１の塗装色目を調整し、さらに塗装硬度を向上させる役割を有する。さらに、上塗り塗料層４０ｂは、マグネシウム合金鍛造ホイール１の塗装外観とホイールの表面硬度を向上させる役割を有する。本発明のマグネシウム合金鍛造ホイール１は、上記保護層４０を備えることによって、自動車用ホイールに要求される、超軽量化、耐温水性、防錆性等の長時間にわたる耐食性に加えて、さらに、マグネシウム合金鍛造ホイール１が奏する意匠性の観点から、機能美、装飾美を備えた製品となる。 The intermediate coating layer 40a has a role of adjusting the coating color of the magnesium alloy forged wheel 1 and further improving the coating hardness. Further, the top coat layer 40b has a role of improving the appearance of the magnesium alloy forged wheel 1 and the surface hardness of the wheel. The magnesium alloy forged wheel 1 of the present invention is provided with the protective layer 40, so that in addition to long-term corrosion resistance required for automobile wheels, such as ultra-lightening, hot water resistance, rust resistance, etc., From the viewpoint of the design characteristics exhibited by the magnesium alloy forged wheel 1, the product has functional beauty and decorative beauty.
　中塗り層４０ａは、プライマー層３０を下塗り層とし、所望により、プライマー層３０上にアクリル樹脂系粉体塗料を塗装して、中塗り層４０ａとして形成されていてもよい。上記アクリル樹脂系粉体塗料としては公知のものが使用でき、（例えば、商品名：エバクラッドＥＶ５６００ＤＫ、関西ペイント株式会社製）等が使用できる。中塗り層の平均塗装膜厚は、特に制限されるものではなく、マグネシウム合金鍛造ホイール１の用途に応じて、適宜変更することができるものであるが、通常６０～１００μｍである。 The intermediate coating layer 40a may be formed as the intermediate coating layer 40a by using the primer layer 30 as an undercoat layer and, if desired, applying an acrylic resin powder coating on the primer layer 30. A publicly known thing can be used as said acrylic resin type powder coating material (For example, brand name: Evaclad EV5600DK, Kansai Paint Co., Ltd. product) etc. can be used. The average coating thickness of the intermediate coating layer is not particularly limited and can be appropriately changed according to the application of the magnesium alloy forged wheel 1, but is usually 60 to 100 μm.
　さらに、中塗り層４０ａ上に上塗り塗料層４０ｂを形成してもよい。上塗り塗料層４０ｂは、主として美粧効果を付与するためのもので、優れた塗装外観と表面強度を向上させるそれ自体既知の塗料が使用できる。その形態は、有機溶剤及び／又は水を溶媒もしくは分散媒とする液状塗料が好ましく用いられる。該上塗り塗料はアクリル樹脂を主成分とする組成物であり、さらに必要に応じて着色顔料やメタリック顔料等を配合してなる。該樹脂組成物は基体樹脂と硬化剤とからなっている。 Furthermore, a top coating layer 40b may be formed on the intermediate coating layer 40a. The top coating layer 40b is mainly for imparting a cosmetic effect, and a coating material known per se for improving an excellent coating appearance and surface strength can be used. As the form, a liquid paint using an organic solvent and / or water as a solvent or a dispersion medium is preferably used. The top coating is a composition containing an acrylic resin as a main component, and further contains a color pigment, a metallic pigment, or the like as necessary. The resin composition comprises a base resin and a curing agent.
　基体樹脂としては、例えばアクリル樹脂、アルキド樹脂、ポリエステル樹脂、フッ素樹脂及びＳｉ含有樹脂等があげられ、硬化剤としてはアミノ樹脂、ポリイソシアネート化合物（ブロック化合物も含む）等が好ましい。例として、アクリル樹脂系着色溶剤塗料、（例えば、商品名：マジクロンＡＬ－２２００、関西ペイント株式会社製）を塗装して上塗り層４０ｂを形成し、更にアクリル樹脂系クリアコート溶剤塗料を塗装することができる。 Examples of the base resin include acrylic resins, alkyd resins, polyester resins, fluororesins, and Si-containing resins, and preferred examples of the curing agent include amino resins and polyisocyanate compounds (including block compounds). As an example, an acrylic resin-based colored solvent paint (for example, trade name: Magiclon AL-2200, manufactured by Kansai Paint Co., Ltd.) is applied to form a top coat layer 40b, and an acrylic resin-based clear coat solvent paint is further applied. Can do.
　プライマー層３０上に積層される保護層４０は、上記中塗り層４０ａ及び上塗り層４０ｂのバリエーションに限定されるものではない。プライマー層３０上に積層される保護層４０は、あらゆる自動車車種に応じて考案される複雑な形状を有するマグネシウム合金鍛造ホイールの用途に応じて、種々の形態を採ることができる。具体的には、保護層４０を中塗り層４０ａ及び上塗り層４０ｂに加え、さらに新たな機能を有する保護層を保護層４０の最も上層に積層してもよいし、保護層４０を中塗り層４０ａと上塗り層４０ｂの間に積層してもよい。 The protective layer 40 laminated on the primer layer 30 is not limited to the variations of the intermediate coating layer 40a and the top coating layer 40b. The protective layer 40 laminated on the primer layer 30 can take various forms depending on the use of the magnesium alloy forged wheel having a complicated shape devised in accordance with any automobile model. Specifically, the protective layer 40 may be added to the intermediate coating layer 40a and the top coating layer 40b, and a protective layer having a new function may be laminated on the uppermost layer of the protective layer 40. You may laminate | stack between 40a and the overcoat layer 40b.
＜マグネシウム合金鍛造ホイールの製造方法＞
　本発明のマグネシウム合金鍛造ホイールの製造方法は、マグネシウム合金鍛造素材を表面処理する工程（ｉ）、表面処理工程後のマグネシウム合金鍛造素材を前処理する工程（ｉｉ）（化成皮膜層形成）、下塗り工程（ｉｉｉ）（プライマー層形成）、及び所望により保護層形成工程（ｉｖ）（中塗り層形成及び／又は上塗り層形成）を備えている。以下、各工程につき詳細に説明する。 <Manufacturing method of magnesium alloy forged wheel>
The method for producing a magnesium alloy forged wheel according to the present invention includes a step (i) of surface-treating a magnesium alloy forged material, a step (ii) of pre-treating the magnesium alloy forged material after the surface treatment step (forming a conversion coating layer), and undercoating It includes a step (iii) (primer layer formation) and, if desired, a protective layer formation step (iv) (intercoat layer formation and / or overcoat layer formation). Hereinafter, each process will be described in detail.
（マグネシウム合金鍛造素材を表面処理する工程（ｉ））
　マグネシウム合金鍛造素材１０を表面処理する工程は、マグネシウム合金鍛造素材１０の表面に付着した不純物を物理的に取り除くこと、及び後に形成される化成皮膜層、プライマー層等との密着性を向上させることを目的とする。さらに、マグネシウム合金鍛造素材１０の表面の凹凸を均一化し、塗装後の塗装表面の外観を良くするために行われる。 (Process (i) for surface treatment of magnesium alloy forging material)
The step of surface-treating the magnesium alloy forging material 10 is to physically remove impurities adhering to the surface of the magnesium alloy forging material 10 and to improve the adhesion with a chemical conversion film layer, a primer layer, etc. to be formed later. With the goal. Furthermore, it is performed in order to make the unevenness of the surface of the magnesium alloy forging material 10 uniform and improve the appearance of the painted surface after painting.
　マグネシウム合金鍛造素材１０を表面処理する工程において、採用される表面処理としては、ブラスト処理が一般的である。ブラスト処理は、素材表面の不純物の除去及び粗面とすることでアンカー効果があり、砂状のステンレス、ジルコンやアランダム粒子を素材表面に高圧で吹き付ける方法である。マグネシウム合金鍛造素材１０は、ジルコン又は酸化アルミナ粒子を使用するのが好ましい。 In the step of surface treating the magnesium alloy forging material 10, blasting is generally used as the surface treatment. The blasting treatment has an anchor effect by removing impurities and roughening the surface of the material, and is a method of spraying sandy stainless steel, zircon and alundum particles onto the material surface at high pressure. The magnesium alloy forging material 10 preferably uses zircon or alumina oxide particles.
（マグネシウム合金鍛造素材１０を前処理する工程（ｉｉ））
　マグネシウム合金鍛造素材１０を前処理する工程により、表面処理されたマグネシウム合金鍛造素材１０上に化成皮膜層２０が形成される。前処理する工程は、以下の工程（ｉｉ）－１～工程（ｉｉ）－３を備えている。具体的は、脱脂処理後、水洗及び表面調整を１回又は数回繰り返し、水洗後、化成皮膜処理を行うことにより行われる。化成皮膜処理後は、温水洗、エアーブロー及び乾燥後、次の塗装工程に付される。 (Step (ii) of pre-processing the magnesium alloy forging material 10)
The chemical conversion coating layer 20 is formed on the surface-treated magnesium alloy forging material 10 by the step of pretreating the magnesium alloy forging material 10. The pretreatment step includes the following steps (ii) -1 to (ii) -3. Specifically, after the degreasing treatment, washing with water and surface adjustment are repeated once or several times, and after washing with water, a chemical conversion film treatment is performed. After the chemical conversion film treatment, it is subjected to the next painting step after washing with warm water, air blowing and drying.
　工程（ｉｉ）－１：脱脂処理は通常、ｐＨ１０～１３程度のアルカリ浴液、例えば水酸化ナトリウム水溶液等であって、室温以上で５０℃以下の温度、例えば４０～４５℃の温度のアルカリ浴液を用いて行われる。また、脱脂処理のための浴液ｐＨを１３以上で行なう方法も含まれる。この方法によれば、マグネシウム合金鍛造素材１０をその不働態域にて脱脂処理を行なうことによって、次工程の化成皮膜処理においてより安定した化成皮膜層２０を得ることができる。この脱脂浴液についてｐＨを１３以上に高めるには、苛性アルカリ等の配合量を増量することによることができる。 Step (ii) -1: The degreasing treatment is usually an alkaline bath solution having a pH of about 10 to 13, such as an aqueous sodium hydroxide solution, and an alkaline bath at a temperature of room temperature to 50 ° C., for example, 40 to 45 ° C. It is performed using a liquid. Moreover, the method of performing bath solution pH for degreasing at 13 or more is also included. According to this method, by performing the degreasing treatment on the magnesium alloy forging material 10 in the passive state region, it is possible to obtain a more stable chemical conversion coating layer 20 in the chemical conversion coating treatment of the next step. In order to raise pH to 13 or more about this degreasing bath liquid, it can be based on increasing the compounding quantity, such as caustic.
　工程（ｉｉ）－２：上記表面調整は、無機酸及び／又は有機酸を用いることができ、無機酸としては、例えば、硫酸、リン酸等が挙げられる。有機酸としては、例えば、クエン酸、リンゴ酸、グルコン酸、酢酸等が挙げられる。この工程（ｉｉ）－２により素材表面から数μｍの表層を除去することで、離型剤や不純物の除去が可能となり、後に続く、工程の化成皮膜処理における、化成皮膜の形成を良好なものとすることができる。 Step (ii) -2: For the surface adjustment, an inorganic acid and / or an organic acid can be used. Examples of the inorganic acid include sulfuric acid and phosphoric acid. Examples of the organic acid include citric acid, malic acid, gluconic acid, acetic acid and the like. By removing the surface layer of several μm from the surface of the material by this step (ii) -2, it becomes possible to remove the mold release agent and impurities, and the formation of the chemical conversion film in the subsequent chemical conversion film treatment is good. It can be.
　工程（ｉｉ）－３：上記化成皮膜処理は、カルシウムイオン（Ｃａ２＋）、マンガンイオン（Ｍｎ２＋）及びリン酸イオン（ＰＯ４ ３－）を含み、Ｃａ／Ｍｎの重量比が０．５以下、好ましくは０．４０～０．５０の水性化成処理液にて、Ｍｇ合金素材を処理することからなる。上記水性化成処理液は、カルシウムイオンを０．３～０．６ｇ／ｌ、マンガンイオンをカルシウムイオンの２倍程度、即ち０．６～１．２ｇ／ｌ、及びリン酸イオンを１０ｇ／ｌ以上の割合で含有されてなる水溶液が好ましい。 Step (ii) -3: The chemical conversion film treatment includes calcium ions (Ca 2+ ), manganese ions (Mn 2+ ), and phosphate ions (PO 4 3− ), and the weight ratio of Ca / Mn is 0.5 or less. Preferably, the Mg alloy material is treated with an aqueous chemical conversion treatment solution of 0.40 to 0.50. The aqueous chemical conversion treatment solution has a calcium ion of 0.3 to 0.6 g / l, a manganese ion of about twice the calcium ion, that is, 0.6 to 1.2 g / l, and a phosphate ion of 10 g / l or more. An aqueous solution containing at a ratio of
　カルシウムイオンが不足あるいは全く含有されない場合には、マグネシウム合金鍛造ホイール１の耐温水性、防錆性等の長時間にわたる耐食性が低下し、プライマー層３０及び保護層４０との塗装密着性が低下する。またマンガンイオン又はリンイオンが不足あるいは全く含有されない場合には、特に、プライマー層３０及び保護層４０との塗装密着性が低下することに加えて、塩素イオンを含む水との接触により白錆発生等の外観不良の原因となったりする。 When calcium ions are insufficient or not contained at all, the corrosion resistance over a long period of time such as warm water resistance and rust resistance of the magnesium alloy forged wheel 1 is lowered, and the coating adhesion between the primer layer 30 and the protective layer 40 is lowered. . In addition, when manganese ions or phosphorus ions are insufficient or not contained at all, white rust is generated due to contact with water containing chlorine ions, in addition to a decrease in paint adhesion with the primer layer 30 and the protective layer 40. May cause poor appearance.
　カルシウムイオン源として、硝酸カルシウム、亜硝酸カルシウム、チオ硫酸カルシウム及びリン酸ニカルシウムの１種又は２種以上が使用し得るが、硝酸カルシウムが好ましい。マンガンイオン源として、硝酸マンガン、リン酸水素マンガン、重リン酸マンガン及びホウフッ化マンガンの１種又は２種以上が使用し得るが、硝酸マンガンが好ましい。リン酸イオン源として、オルソリン酸、縮合リン酸、亜リン酸及び次亜リン酸の１種又は２種以上が使用し得るが、オルソリン酸が好ましい。 As the calcium ion source, one or more of calcium nitrate, calcium nitrite, calcium thiosulfate and dicalcium phosphate can be used, and calcium nitrate is preferred. As the manganese ion source, one or more of manganese nitrate, manganese hydrogen phosphate, manganese biphosphate, and manganese borofluoride can be used, and manganese nitrate is preferable. As the phosphate ion source, one or more of orthophosphoric acid, condensed phosphoric acid, phosphorous acid and hypophosphorous acid can be used, and orthophosphoric acid is preferred.
　上記化成処理液は１．０乃至３．０のｐＨに調整されるのが好ましい。該処理液が１．０乃至３．０のｐＨに調整されると、マグネシウム合金鍛造素材１０表面上に化成皮膜層を効果的に且つ支障なく形成することが可能となる。また、この化成処理液の温度条件は、被処理材表面となるマグネシウム合金鍛造素材１０表面との接触時間と相関関係にある。 It is preferable that the chemical conversion solution is adjusted to a pH of 1.0 to 3.0. When the treatment liquid is adjusted to a pH of 1.0 to 3.0, a chemical conversion coating layer can be formed effectively and without hindrance on the surface of the magnesium alloy forging material 10. Moreover, the temperature conditions of this chemical conversion liquid have a correlation with the contact time with the magnesium alloy forging raw material 10 surface used as the to-be-processed material surface.
　すなわち、上記化成処理液温度が比較的に室温程度である場合には、この接触時間は長い方が好ましく、また浴液温度が８０℃程度である場合には、この接触時間は短い方が好ましい関係となっている。 That is, when the chemical conversion treatment liquid temperature is relatively about room temperature, the contact time is preferably longer, and when the bath liquid temperature is about 80 ° C., the contact time is preferably shorter. It has become a relationship.
　具体的には、室温以上、好ましくは３０℃以上８０℃以下の温度で１～１０分間、特に４５～５５℃で１～５分間接触するのが好ましい。上記化成処理液の温度が３０℃未満であると、前記した化成皮膜の形成にとって長時間が必要となり、得られる化成皮膜層に要求される性能が不十分となる。また８０℃を超える温度となると、過剰反応により却って得られる化成皮膜について性能の低下を招くことがある。 Specifically, the contact is preferably performed at a temperature of room temperature or higher, preferably 30 ° C. or higher and 80 ° C. or lower for 1 to 10 minutes, particularly 45 to 55 ° C. for 1 to 5 minutes. When the temperature of the chemical conversion treatment liquid is less than 30 ° C., it takes a long time to form the chemical conversion film, and the performance required for the obtained chemical conversion film layer becomes insufficient. When the temperature exceeds 80 ° C., the performance of the chemical conversion film obtained by excessive reaction may be reduced.
　上記化成皮膜処理により、カルシウムが１～１５０ｍｇ／ｍ２、好ましくは１０～１１０ｍｇ／ｍ２、マンガンが２～３８０ｍｇ／ｍ２、好ましくは２０～２８０ｍｇ／ｍ２、リンが１～６００ｍｇ／ｍ２、好ましくは１０～４００ｍｇ／ｍ２を含む化成皮膜層２０が得られる。 By the chemical conversion film treatment, calcium is 1 to 150 mg / m 2 , preferably 10 to 110 mg / m 2 , manganese is 2 to 380 mg / m 2 , preferably 20 to 280 mg / m 2 , and phosphorus is 1 to 600 mg / m 2. Thus, the chemical conversion film layer 20 containing 10 to 400 mg / m 2 is obtained.
（プライマー層３０形成工程（ｉｉｉ））
　プライマー層３０形成工程（ｉｉｉ）は、上記前処理工程（ｉｉ）により化成皮膜層２０を形成したマグネシウム合金鍛造素材１０を温水洗い及びエアーブロー乾燥後、エポキシ樹脂系プライマー塗料を塗布してプライマー層３０を形成する工程である。該エポキシ樹脂としては、上記述べたエポキシ樹脂を使用することができる。 (Primer layer 30 forming step (iii))
In the primer layer 30 forming step (iii), the magnesium alloy forged material 10 on which the chemical conversion film layer 20 has been formed in the pretreatment step (ii) is washed with warm water and air blow dried, and then an epoxy resin primer coating is applied to the primer layer 30 30. The epoxy resin described above can be used as the epoxy resin.
　上記プライマー層３０は、上記プライマー塗料の塗装後、ｏｎ　ｗｅｔ（常温乾燥のライン工程上で、通常４～５分間）又は乾燥条件１００℃、２０～３０分間することにより形成される。該プライマー層３０の平均塗装膜厚は、目的とする製品によるが、ホイールの場合、１０～２０μｍである。該プライマー層３０の形成により、上記化成皮膜層２０と下記の保護層４０である塗装層（中塗り層）との密着性が付与され、更に耐温水性、防錆性等の長時間にわたる耐食性が向上する。 The primer layer 30 is formed by applying on primer (usually 4 to 5 minutes on the room temperature drying line process) or drying conditions at 100 ° C. for 20 to 30 minutes after the primer coating is applied. The average coating film thickness of the primer layer 30 depends on the target product, but in the case of a wheel, it is 10 to 20 μm. By forming the primer layer 30, adhesion between the chemical conversion film layer 20 and the coating layer (intercoat layer) which is the following protective layer 40 is imparted, and furthermore, corrosion resistance over a long period of time such as warm water resistance and rust resistance. Will improve.
（保護層４０形成工程（ｉｖ）：中塗り層形成及び／又は上塗り層形成）
　図６は、保護層を備えたマグネシウム合金鍛造ホイール１の断面構造の拡大モデル図である。図６に示されるように、本発明のマグネシウム合金鍛造ホイール１は、所望により、プライマー層３０を形成した素材にアクリル樹脂系粉体塗料を塗装して保護層４０となる中塗り層４０ａを形成することができる。該アクリル樹脂系粉体塗料としては公知のものが使用できるが、例えば、商品名：エバクラッドＥＶ５６００ＤＫ、関西ペイント株式会社製等が使用できる。保護層４０となる該中塗り層の平均塗装膜厚は通常６０～１００μｍである。 (Protective layer 40 forming step (iv): intermediate coating layer formation and / or top coating layer formation)
FIG. 6 is an enlarged model diagram of a cross-sectional structure of the magnesium alloy forged wheel 1 provided with a protective layer. As shown in FIG. 6, the magnesium alloy forged wheel 1 of the present invention forms an intermediate coating layer 40 a to be a protective layer 40 by coating an acrylic resin powder coating on the material on which the primer layer 30 is formed, if desired. can do. Known acrylic resin-based powder coatings can be used. For example, trade names: EVA Clad EV5600DK, manufactured by Kansai Paint Co., Ltd., and the like can be used. The average coating thickness of the intermediate coating layer serving as the protective layer 40 is usually 60 to 100 μm.
　さらに、中塗り層４０ａを形成した素材に、上塗り塗料層４０ｂを形成することができる。この上塗り塗料は、主として美粧効果を付与するためのもので、優れた塗装外観と表面強度を向上させ、それ自体既知の塗料が使用できる。塗料の形態は、有機溶剤及び／又は水を溶媒もしくは分散媒とする液状塗料が好ましく用いられる。該上塗り塗料の成分等は既に説明した通りである。 Furthermore, the top coating layer 40b can be formed on the material on which the intermediate coating layer 40a is formed. This top coating is mainly for imparting a cosmetic effect, improves the appearance of the coating and the surface strength, and a coating known per se can be used. As the form of the paint, a liquid paint using an organic solvent and / or water as a solvent or a dispersion medium is preferably used. The components of the top coating composition are as described above.
　以下、実施例を比較例と共に挙げ、本発明の効果を具体的に説明するが、本発明はかかる実施例に限定されるものではない。 Hereinafter, although an example is given with a comparative example and the effect of the present invention is explained concretely, the present invention is not limited to such an example.
＜実施例１＞
　上記マグネシウム合金鍛造ホイールの製造方法により、マグネシウム合金鍛造ホイール１を製造した。マグネシウム合金鍛造素材１０は、ＡＳＴＭ規格品ＡＺ８０に準じるマグネシウム合金を用いた。このマグネシウム合金を１方向鍛造方式にて、鍛錬比６程度にて成型した。マグネシウム合金に含まれるマグネシウム粒子の平均結晶粒子径６０μｍとし、微粒子化した。マグネシウム合金鍛造素材１０の成分は、鉄（Ｆｅ）０．００５重量％以下であり、銅（Ｃｕ）０．０５５重量％以下、ニッケル（Ｎｉ）０．００５重量％以下のものである。 <Example 1>
The magnesium alloy forged wheel 1 was manufactured by the manufacturing method of the said magnesium alloy forged wheel. As the magnesium alloy forging material 10, a magnesium alloy according to ASTM standard product AZ80 was used. This magnesium alloy was molded by a unidirectional forging method at a forging ratio of about 6. The average crystal particle diameter of magnesium particles contained in the magnesium alloy was made 60 μm to make fine particles. The component of the magnesium alloy forging material 10 is 0.005 wt% or less of iron (Fe), 0.055 wt% or less of copper (Cu), and 0.005 wt% or less of nickel (Ni).
　化成皮膜層２０を形成するために使用する処理液は、リン酸マンガンカルシウム処理液（商品名：グランダーＭＣ－１０００Ｗ、ミリオン化学株式会社製）を使用した。マグネシウム合金鍛造素材１０を脱脂処理後、上記処理液と接触させた後、水洗及び下記表面調整を１又は２回繰り返し、水洗後、マグネシウム合金鍛造素材１０上に、乾燥前の化成皮膜層２０を形成させた。上記化成皮膜層２０を更に温水洗浄後、エアーブロー及び乾燥し、マグネシウム合金鍛造素材１０上に化成皮膜層２０を形成させた。具体的には、以下の手順の通りにて行った。 The treatment liquid used to form the chemical conversion film layer 20 was a manganese calcium phosphate treatment liquid (trade name: Grander MC-1000W, manufactured by Million Chemical Co., Ltd.). After the magnesium alloy forged material 10 is degreased and brought into contact with the above treatment liquid, washing with water and the following surface adjustment are repeated once or twice, and after washing with water, the conversion coating layer 20 before drying is formed on the magnesium alloy forged material 10. Formed. The chemical conversion film layer 20 was further washed with warm water, then air blown and dried to form the chemical conversion film layer 20 on the magnesium alloy forging material 10. Specifically, the procedure was as follows.
　具体的には、以下の手順の通りにて行った。（１）脱脂：アルカリ性脱脂液；水道水を使用し、７０℃で５分間撹拌浸漬。（２）水洗：水道水で３０秒間水洗。（３）表面調整１：処理；イオン交換水を使用し、６０℃で１分間撹拌浸漬。（４）水洗：水道水で３０秒間水洗。（５）表面調整２：スマット処理イオン交換水を使用し、６０℃で７分間撹拌浸漬。（６）湯洗：水道水６０℃で３０秒間水洗。（７）リン酸マンガンカルシウム系処理：イオン交換水を使用し、５０℃で３分間撹拌浸漬。（８）純水洗：イオン交換水を使用し、３０秒間シャワー水洗。（９）純水洗：イオン交換水を使用し、５０℃で１分間浸漬水洗。（１０）エアーブロー：表面に付着した水滴や水溜り部の水をエアーで１５秒間程度吹き飛ばす。（１１）乾燥：８０℃熱風で、１５～３０分間乾燥。 Specifically, the following procedure was followed. (1) Degreasing: Alkaline degreasing solution; using tap water, stirring and soaking at 70 ° C. for 5 minutes. (2) Washing with water: Washing with tap water for 30 seconds. (3) Surface adjustment 1: Treatment; Ion-exchanged water was used and stirred and immersed at 60 ° C. for 1 minute. (4) Washing with water: Washing with tap water for 30 seconds. (5) Surface adjustment 2: Smut-treated ion-exchanged water was used and stirred and dipped at 60 ° C. for 7 minutes. (6) Hot water washing: Washing with tap water at 60 ° C. for 30 seconds. (7) Manganese calcium phosphate system treatment: Ion-exchanged water is used and stirred for 3 minutes at 50 ° C. (8) Pure water washing: shower water washing using ion exchange water for 30 seconds. (9) Pure water washing: Ion-exchange water is used, and immersion water washing is performed at 50 ° C for 1 minute. (10) Air blow: Water droplets adhering to the surface or water in the pool are blown off with air for about 15 seconds. (11) Drying: Drying with hot air at 80 ° C. for 15 to 30 minutes.
　次に、マグネシウム合金鍛造素材１０上に形成された化成皮膜層２０上にプライマー層３０を形成させた。プライマー層３０の形成は、下記表２に示す塗料種を使用し、以下の方法よって、化成皮膜層２０にエポキシ系樹脂プライマーを塗布することにより行った。なお、エポキシ樹脂系プライマー塗料には、（商品名：ＢＳプライマー、大日本塗料株式会社製）、特殊変性エポキシ樹脂系ワニスを主剤とし、重量平均分子量９，０００～１０，０００程度に高分子化し、メラニン樹脂系ワニスを添加した塗料を用いた。 Next, a primer layer 30 was formed on the chemical conversion film layer 20 formed on the magnesium alloy forging material 10. The primer layer 30 was formed by applying an epoxy resin primer to the chemical conversion coating layer 20 by the following method using the coating types shown in Table 2 below. The epoxy resin-based primer paint (trade name: BS primer, manufactured by Dainippon Paint Co., Ltd.) has a specially modified epoxy resin-based varnish as the main agent, and has a weight average molecular weight of about 9,000 to 10,000. A paint to which a melanin resin varnish was added was used.
　具体的には、４３．４重量％の特殊変性エポキシ樹脂系ワニスＡに２．１重量％エポキシ樹脂ワニス及び１．６重量％メラミン樹脂ワニスを添加し、更に３３．４重量％の顔料を添加し、０．５重量％の添加剤と１９．０重量％の溶剤を添加したエポキシ樹脂系プライマー塗料をマグネシウム合金鍛造素材１０上にスプレー塗装にて塗布した。そして、乾燥前のプライマー層３０を膜厚１０～２０μｍとし、その後、室温にて５～１０分間放置して乾燥させた。乾燥後、マグネシウム合金鍛造素材１０に化成皮膜層２０とプライマー層３０とを備えた本発明のマグネシウム合金鍛造ホイール１とした。 Specifically, 2.1 wt% epoxy resin varnish and 1.6 wt% melamine resin varnish are added to 43.4 wt% specially modified epoxy resin varnish A, and 33.4 wt% pigment is further added. Then, an epoxy resin-based primer paint added with 0.5 wt% additive and 19.0 wt% solvent was applied onto the magnesium alloy forging material 10 by spray coating. The primer layer 30 before drying was made to have a film thickness of 10 to 20 μm, and then left to dry at room temperature for 5 to 10 minutes. After drying, the magnesium alloy forged wheel 1 of the present invention was provided with the chemical film layer 20 and the primer layer 30 on the magnesium alloy forged material 10.
（保護層４０の形成：中塗り層及び上塗り層）
　さらに、上記マグネシウム合金鍛造ホイール１に対し、以下の工程に順じた塗装を施し、プライマー層３０上に中塗り層及び上塗り層を形成させた。具体的な塗装工程は、中塗り塗装１→焼付け→中塗り塗装２→焼付け→上塗り１塗装→ｗｅｔ→上塗り塗装２→焼付けの手順にて行った。 (Formation of protective layer 40: intermediate coating layer and top coating layer)
Further, the magnesium alloy forged wheel 1 was coated in accordance with the following steps, and an intermediate coating layer and a top coating layer were formed on the primer layer 30. The specific coating process was performed in the order of intermediate coating 1 → baking → intermediate coating 2 → baking → top coating 1 → wet → top coating 2 → baking.
　中塗り塗装は、アクリル樹脂系粉体塗料（商品名：エバクラッドＥＶ５６００ＤＫ、関西ペイント株式会社製）を使用し、乾燥条件１６０℃で４０分間焼付けた（中塗り塗装１）。その上にアクリル樹脂系プライマー溶剤塗料（商品名：マジクロンＡＬＣ－２、関西ペイント株式会社製）を使用し、乾燥条件１５５℃で４０分間焼付けた（中塗り塗装２）。上塗り塗装は、アクリル樹脂系着色溶剤塗料（商品名：マジクロンＡＬ－２２００、関西ペイント株式会社製）を使用し、室温でｏｎ　ｗｅｔ乾燥した（上塗り塗装１）上にアクリル樹脂系クリアコート溶剤塗料（商品名：クリア塗料マジクロンＡＬＣ－１００、関西ペイント株式会社製）を使用し、乾燥条件１５５℃で４０分間焼付けた（上塗り塗装２）。 In the intermediate coating, an acrylic resin powder coating (trade name: Evaclad EV5600DK, manufactured by Kansai Paint Co., Ltd.) was used and baked for 40 minutes at 160 ° C. under dry conditions (intermediate coating 1). On top of that, an acrylic resin-based primer solvent paint (trade name: Magiclon ALC-2, manufactured by Kansai Paint Co., Ltd.) was used and baked for 40 minutes at 155 ° C. under dry conditions (intermediate coating 2). For the top coating, an acrylic resin-based colored solvent paint (trade name: Magiclon AL-2200, manufactured by Kansai Paint Co., Ltd.) was used and dried on wet at room temperature (top coating 1). Product name: Clear paint Magiclon ALC-100 (manufactured by Kansai Paint Co., Ltd.) was used and baked at 155 ° C. for 40 minutes (top coating 2).
＜実施例２、３＞
　実施例１のマグネシウム合金鍛造ホイールにおいて、化成皮膜層２０に含まれるカルシウム、マンガン及びリンの含有量を変化させた以外は、実施例１と同様にして、マグネシウム合金鍛造ホイールを製造した。 <Examples 2 and 3>
In the magnesium alloy forged wheel of Example 1, a magnesium alloy forged wheel was produced in the same manner as in Example 1 except that the contents of calcium, manganese and phosphorus contained in the chemical conversion film layer 20 were changed.
＜実施例４＞
　表１に示すように、プライマー層２０に使用するエポキシ樹脂系プライマー塗料が防錆剤を含まないこと以外は、実施例１と同様にしてマグネシウム合金鍛造ホイールを製造した。実施例４において、保護層４０ａが有している中塗層を形成する際に使用されたアクリル樹脂系プライマー溶剤塗料（商品名：マジクロンＡＬＣ－２）は、その成分として、二酸化チタン（ＴｉＯ２）と、カーボンとを含んでいる。実施例４において製造されたマグネシウム合金鍛造ホイールは、二酸化チタン（ＴｉＯ２）の影響によりシルバー系の色彩を有している。 <Example 4>
As shown in Table 1, a magnesium alloy forged wheel was produced in the same manner as in Example 1 except that the epoxy resin-based primer paint used for the primer layer 20 did not contain a rust inhibitor. In Example 4, the acrylic resin-based primer solvent paint (trade name: Magiclon ALC-2) used for forming the intermediate coating layer included in the protective layer 40a has titanium dioxide (TiO 2 ) as its component. ) And carbon. The magnesium alloy forged wheel manufactured in Example 4 has a silver color due to the influence of titanium dioxide (TiO 2 ).
　具体的には、使用したエポキシ樹脂系プライマーは、４５．２重量％の特殊変性エポキシワニスＡに２．２重量％のエポキシ樹脂ワニス及び１．７重量％のメラミン樹脂ワニスと３０．１重量％の体質顔料・着色顔料及び２０．８重量％の溶剤と添加剤を添加したものを使用した。 Specifically, the epoxy resin-based primer used was 45.2% by weight of specially modified epoxy varnish A, 2.2% by weight of epoxy resin varnish, 1.7% by weight of melamine resin varnish and 30.1% by weight. 1 and 20.8% by weight of solvent and additives were used.
＜比較例１、２＞
　表１に示すように、プライマー層２０に使用するエポキシ樹脂系プライマー塗料の組成は実施例１と同様として、化成皮膜層２０に含まれるカルシウム、マンガンの含有量を変化させて、実施例１と同様にしてマグネシウム合金鍛造ホイールを製造した。 <Comparative Examples 1 and 2>
As shown in Table 1, the composition of the epoxy resin-based primer paint used for the primer layer 20 is the same as that of Example 1, and the contents of calcium and manganese contained in the chemical conversion film layer 20 are changed. Similarly, a magnesium alloy forged wheel was manufactured.
＜参考例１＞
　実施例１のマグネシウム合金鍛造ホイールにおいて、マグネシウム合金鍛造素材１０に替えて、汎用品として使用されているアルミニウム合金鍛造素材を使用した以外は、実施例１と同様にしてアルミニウム合金鍛造ホイールを製造した。なお、参考例１は、上記アルミニウム合金鍛造素材を使用した場合の性能比較であり、化成皮膜を形成させるために使用する前処理は、シランカップリング法であり、エポキシ樹脂系プライマーは実施例及び比較例で採用したエポキシ樹脂系プライマーと異なるものである。 <Reference Example 1>
In the magnesium alloy forged wheel of Example 1, an aluminum alloy forged wheel was manufactured in the same manner as in Example 1 except that an aluminum alloy forged material used as a general-purpose product was used instead of the magnesium alloy forged material 10. . In addition, Reference Example 1 is a performance comparison when the above-described aluminum alloy forging material is used, the pretreatment used for forming the chemical conversion film is a silane coupling method, and the epoxy resin primer is used in the examples and This is different from the epoxy resin primer used in the comparative example.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
＜マグネシウム合金鍛造ホイールの評価＞
　実施例、比較例及び参考例において製造したマグネシウム合金鍛造ホイールについて（１）初期密着性評価（ＪＩＳ　Ｋ－５４００）、（２）耐温水性評価（ＪＩＳ　Ｋ　６８４８）、耐食性評価　ＣＡＳＳ試験評価（Copper-accelerated Acetic acid Salt Spray test）及び（４）耐食性評価ＳＳＴ試験評価（塩水噴霧試験ＪＩＳ－Ｚ２３７１）を評価した。評価結果を表２に示す。 <Evaluation of magnesium alloy forged wheels>
Magnesium alloy forged wheels manufactured in Examples, Comparative Examples and Reference Examples (1) Initial adhesion evaluation (JIS K-5400), (2) Warm water resistance evaluation (JIS K 6848), Corrosion resistance evaluation CASS test evaluation (Copper -accelerated acetic acid salt spray test) and (4) corrosion resistance evaluation SST test evaluation (salt spray test JIS-Z2371) was evaluated. The evaluation results are shown in Table 2.
（１）初期密着性評価初期密着性評価（ＪＩＳ　Ｋ－５４００）
　マグネシウム合金鍛造ホイールを製造後、１日間室温放置した後、室温下で塗装表面に指定治具を使用し、指定のカッターを用いて碁盤目１００枡目を作製し、指定された剥離用テープ（ニチバン製ＣＴ）を使用して縦横２方向から各１回剥離試験評価する。剥れない枡目と１００枡目を５０／１００のように表示し、合格基準は１００／１００とした。上記合格基準を満たすマグネシウム合金鍛造ホイールの評価を良好（合格）とした。 (1) Initial adhesion evaluation Initial adhesion evaluation (JIS K-5400)
After manufacturing the magnesium alloy forged wheel, let stand at room temperature for 1 day, then use the specified jig on the painted surface at room temperature, make 100 grids with the specified cutter, specify the specified peeling tape ( Nichiban CT) is used to evaluate the peel test once each from two directions. The squares that do not peel and the 100th square are displayed as 50/100, and the acceptance criterion is 100/100. A magnesium alloy forged wheel that satisfies the above acceptance criteria was evaluated as good (accepted).
（２）耐温水性評価（ＪＩＳ　Ｋ　６８４８）
　イオン交換水を使用し水温４０℃で１８０～２４０時間被検体を浸漬し、被検体は温水に浸漬後室温に２～４時間放置し室温状態に戻す。６０時間毎に被検体の密着性を検査し良否の判定を行う。密着性評価は、上記の初期密着性評価基準に準じた。上記合格基準を満たすマグネシウム合金鍛造ホイールの評価を良好（合格）とした。併せて、マグネシウム合金鍛造ホイールが密着状態を保持することができる時間を測定した。 (2) Hot water resistance evaluation (JIS K 6848)
Ion exchange water is used and the specimen is immersed for 180 to 240 hours at a water temperature of 40 ° C. The specimen is immersed in warm water and left at room temperature for 2 to 4 hours to return to room temperature. Every 60 hours, the adhesion of the subject is inspected to determine whether it is good or bad. The adhesion evaluation was in accordance with the above initial adhesion evaluation criteria. A magnesium alloy forged wheel that satisfies the above acceptance criteria was evaluated as good (accepted). In addition, the time during which the magnesium alloy forged wheel can maintain a close contact state was measured.
（３）耐食性評価　ＣＡＳＳ試験評価（Copper-accelerated Acetic acid Salt Spray test）
　予め指定されたＸカット法により、マグネシウム合金鍛造ホイールのマグネシウム合金鍛造素材１０まで達する線引きを行い、指定されたＣＡＳＳ試験装置に被検体をセットし、２４０時間まで６０時間ごとに取り出して被検体が室温状態に戻るまで、約２～４時間室温で放置後、目視観測にて「膜膨れ」状態、「錆」状態を特定した後、定規をあてて、最大の膨れ部分の測定を行う。３ｍｍ以下を合格基準とした。 (3) Corrosion resistance evaluation CASS test evaluation (Copper-accelerated Acetic acid Salt Spray test)
Using a predesignated X-cut method, the magnesium alloy forging wheel is drawn to reach the magnesium alloy forging material 10, the specimen is set in the designated CASS test apparatus, and the specimen is taken out every 60 hours up to 240 hours. After returning to room temperature for about 2-4 hours at room temperature, visually identify the “film bulge” and “rust” conditions, and then apply a ruler to measure the largest bulge. The acceptance standard was 3 mm or less.
（４）耐食性評価　ＳＳＴ試験評価（塩水噴霧試験ＪＩＳ－Ｚ２３７１）
　試験片の半分にカッターナイフを用いて素材に達するクロスカットを入れ、残り半分にチッビングを施す。５％塩化ナトリウム水溶液を用いて温度３５±１℃の塩水噴霧試験機に放置する。１２０時間毎に取り出して水洗しクロスカット、エッジ及びチッビング傷からの錆、膨れの発生を測定する。３．０ｍｍ以下を合格基準とした。なお、上記の評価は鍛造ホイールと同等の成分を有した鍛造板で試験評価した。 (4) Corrosion resistance evaluation SST test evaluation (salt spray test JIS-Z2371)
Put a cross-cut reaching the material into the half of the test piece using a cutter knife, and chip the other half. The sample is left in a salt spray tester at a temperature of 35 ± 1 ° C. using a 5% sodium chloride aqueous solution. Take out every 120 hours, wash with water, and measure the occurrence of rust and blisters from crosscuts, edges and chipping scratches. The acceptance criterion was 3.0 mm or less. In addition, said evaluation was test-evaluated with the forge board which has a component equivalent to a forge wheel.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表２からも明らかなように、本発明のマグネシム合金鍛造ホイールは、（１）初期密着性評価（ＪＩＳ　Ｋ－５４００）、（２）耐温水性評価（ＪＩＳ　Ｋ　６８４８）、（３）耐食性評価　ＣＡＳＳ試験評価（Copper-accelerated Acetic acid Salt Spray test）及び（４）耐食性評価ＳＳＴ試験評価（塩水噴霧試験ＪＩＳ－Ｚ２３７１）のいずれの評価においても、良好な結果を示している。実施例１～４において製造されたマグネシウム合金鍛造ホイールは、参考例１において製造されたアルミニウム合金鍛造ホイールとほぼ同一の初期密着性、耐温水性及び耐食性を備えていることが理解できる。 As is clear from Table 2, the magnesium alloy forged wheel of the present invention has (1) initial adhesion evaluation (JIS K-5400), (2) warm water resistance evaluation (JIS K 6848), and (3) corrosion resistance evaluation. Both the CASS test evaluation (Copper-accelerated Acetic acid Salt Spray test) and (4) corrosion resistance evaluation SST test evaluation (salt spray test JIS-Z2371) show good results. It can be understood that the magnesium alloy forged wheels manufactured in Examples 1 to 4 have substantially the same initial adhesion, hot water resistance, and corrosion resistance as the aluminum alloy forged wheels manufactured in Reference Example 1.
　本発明のマグネシム合金鍛造ホイールは、アルミニウムを合金素材として採用したアルミニウム合金鍛造ホイールとほぼ同程度の耐食性を備えていることが判明した。しかも、マグネシム合金鍛造ホイールは、上記アルミニウム合金鍛造ホイールよりも１５～２５％軽いため、レース用自動車のみならず、一般用自動車に装着された場合の技術的意義は大きい。 It has been found that the magnesium alloy forged wheel of the present invention has almost the same level of corrosion resistance as an aluminum alloy forged wheel employing aluminum as an alloy material. In addition, since the magnesium alloy forged wheel is 15 to 25% lighter than the aluminum alloy forged wheel, the technical significance when mounted on not only a racing car but also a general car is great.
　本発明のマグネシウム合金鍛造ホイールは、超軽量であり、耐温水性、防錆性等の長時間にわたる耐食性をきわめて向上させたものである。本発明のマグネシウム合金鍛造ホイールは、Ｆ１世界選手権等のレース用自動車のみならず、一般用自動車にも適用可能であり、きわめて汎用性が高い。このため、自動車産業全体への貢献は極めて大きい。また、一般用自動車のいわゆる脚周りの軽量化は、消費エネルギーの軽減にも繋がり、エネルギー産業、ひいては環境技術産業への貢献も期待できる。 The magnesium alloy forged wheel of the present invention is ultralight and has extremely improved corrosion resistance over a long period of time, such as warm water resistance and rust resistance. The magnesium alloy forged wheel of the present invention can be applied not only to racing automobiles such as the F1 World Championship but also to general automobiles, and is extremely versatile. For this reason, the contribution to the entire automobile industry is extremely large. In addition, the reduction in weight around the so-called legs of general-purpose automobiles also leads to a reduction in energy consumption, and can be expected to contribute to the energy industry and consequently to the environmental technology industry.
Ｖ　　　　　マグネシウム合金鍛造ホイールを装着した自動車
１　　　　　マグネシウム合金鍛造ホイール
２　　　　　タイヤ
１０　　　　マグネシウム合金鍛造素材
２０　　　　化成皮膜層
３０　　　　プライマー層（下塗り層）
４０ａ　　　保護層（中塗り層）
４０ｂ　　　保護層（上塗り層） V Car 1 equipped with a magnesium alloy forged wheel 1 Magnesium alloy forged wheel 2 Tire 10 Magnesium alloy forged material 20 Chemical conversion coating layer 30 Primer layer (undercoat layer)
40a Protective layer (intercoat layer)
40b Protective layer (overcoat layer)

Claims (5)

  1. 　マグネシウム合金鍛造素材上に形成されたカルシウムとマンガンとリンとを含む化成皮膜層と、前記化成皮膜層上に形成されたプライマー層とを備えた耐食性マグネシウム合金鍛造ホイールであって、
    　前記マグネシウム合金鍛造素材は、その表面に平均結晶粒子径が８０μｍ以下であるマグネシウム粒子を含有し、前記化成皮膜層に含まれるカルシウム／マンガンの付着量重量比は０．４０～０．６０であり、前記プライマー層が重量平均分子量３０，０００以下のエポキシ樹脂を含み、且つ防錆顔料５．０重量％以下を含むエポキシ樹脂系プライマー塗料から形成されたことを特徴とする耐食性マグネシウム合金鍛造ホイール。     A corrosion resistant magnesium alloy forged wheel comprising a chemical conversion film layer containing calcium, manganese and phosphorus formed on a magnesium alloy forging material, and a primer layer formed on the chemical conversion film layer,
    The magnesium alloy forging material contains magnesium particles having an average crystal particle size of 80 μm or less on the surface, and the weight ratio of calcium / manganese adhesion contained in the chemical conversion coating layer is 0.40 to 0.60. A corrosion-resistant magnesium alloy forged wheel, wherein the primer layer comprises an epoxy resin primer paint containing an epoxy resin having a weight average molecular weight of 30,000 or less and containing 5.0 wt% or less of a rust preventive pigment.
  2. 　前記化成皮膜層はカルシウムを１～１５０ｍｇ／ｍ２、マンガンを２～３８０ｍｇ／ｍ２、リンを１～６００ｍｇ／ｍ２含むことを特徴とする請求項１に記載の耐食性マグネシウム合金鍛造ホイール。 The conversion coating layer of calcium 1 ~ 150mg / m 2, manganese 2 ~ 380mg / m 2, corrosion resistance of magnesium alloy forged wheel according to claim 1, characterized in that phosphorus containing 1 ~ 600mg / m 2.
  3. 　前記エポキシ樹脂系プライマー層に含まれるエポキシ樹脂が重量平均分子量９，０００～２０，０００であることを特徴とする請求項１又は２に記載の耐食性マグネシウム合金鍛造ホイール。 The corrosion-resistant magnesium alloy forged wheel according to claim 1, wherein the epoxy resin contained in the epoxy resin-based primer layer has a weight average molecular weight of 9,000 to 20,000.
  4. 　前記プライマー層上に保護層を備えたことを特徴とする請求項１～３のいずれか１項に記載の耐食性マグネシウム合金鍛造ホイール。 The corrosion-resistant magnesium alloy forged wheel according to any one of claims 1 to 3, wherein a protective layer is provided on the primer layer.
  5. 　表面の平均結晶粒子径が８０μｍ以下のマグネシウム合金鍛造ホイール素材の該表面をカルシウムイオンとマンガンイオンとリン酸イオンとを含む化成処理液と接触させて該マグネシウム合金鍛造ホイール素材上にカルシウムとマンガンとリンとを含み、且つカルシウム／マンガンの付着量重量比が０．４０～０．６０の化成皮膜を形成する工程と、
    前記化成皮膜上に重量平均分子量が３０，０００以下のエポキシ樹脂を含み、且つ防錆顔料５．０重量％以下を含むエポキシ樹脂系プライマー塗料を塗装してプライマー層を形成する工程と、を含むことを特徴とする耐食性マグネシウム合金鍛造ホイールの製造方法。     The surface of the magnesium alloy forged wheel material having an average crystal particle size of 80 μm or less is brought into contact with a chemical conversion treatment solution containing calcium ions, manganese ions, and phosphate ions, and calcium and manganese on the magnesium alloy forged wheel material. Forming a chemical conversion film containing phosphorus and having a calcium / manganese adhesion weight ratio of 0.40 to 0.60;
    A step of forming a primer layer by applying an epoxy resin-based primer paint containing an epoxy resin having a weight average molecular weight of 30,000 or less on the chemical conversion film and containing 5.0% by weight or less of a rust preventive pigment. A method for producing a corrosion-resistant magnesium alloy forged wheel.
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