CN117772995A - Environment-friendly efficient stripping sand mold coating for large-scale steel castings and preparation method thereof - Google Patents
Environment-friendly efficient stripping sand mold coating for large-scale steel castings and preparation method thereof Download PDFInfo
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- 238000000576 coating method Methods 0.000 title claims abstract description 196
- 239000011248 coating agent Substances 0.000 title claims abstract description 190
- 238000005266 casting Methods 0.000 title claims abstract description 80
- 239000004576 sand Substances 0.000 title claims abstract description 64
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 44
- 239000010959 steel Substances 0.000 title claims abstract description 44
- 238000002360 preparation method Methods 0.000 title claims abstract description 30
- 239000000843 powder Substances 0.000 claims abstract description 89
- 239000000919 ceramic Substances 0.000 claims abstract description 56
- 239000000375 suspending agent Substances 0.000 claims abstract description 24
- 239000002994 raw material Substances 0.000 claims abstract description 17
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000002562 thickening agent Substances 0.000 claims abstract description 13
- 239000011230 binding agent Substances 0.000 claims abstract description 11
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000005011 phenolic resin Substances 0.000 claims abstract description 9
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- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 claims abstract description 7
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 claims abstract description 7
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- 239000003795 chemical substances by application Substances 0.000 claims abstract description 5
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 42
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical group [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 26
- 239000004408 titanium dioxide Substances 0.000 claims description 18
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- 238000001354 calcination Methods 0.000 claims description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 7
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 6
- 238000009210 therapy by ultrasound Methods 0.000 claims description 6
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- 230000009972 noncorrosive effect Effects 0.000 abstract 1
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 53
- 239000003973 paint Substances 0.000 description 16
- 239000011247 coating layer Substances 0.000 description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 14
- 229910052845 zircon Inorganic materials 0.000 description 13
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 13
- ONCZQWJXONKSMM-UHFFFAOYSA-N dialuminum;disodium;oxygen(2-);silicon(4+);hydrate Chemical group O.[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[Na+].[Na+].[Al+3].[Al+3].[Si+4].[Si+4].[Si+4].[Si+4] ONCZQWJXONKSMM-UHFFFAOYSA-N 0.000 description 12
- 229940080314 sodium bentonite Drugs 0.000 description 12
- 229910000280 sodium bentonite Inorganic materials 0.000 description 12
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- 235000019353 potassium silicate Nutrition 0.000 description 8
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 7
- 239000000725 suspension Substances 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 235000010482 polyoxyethylene sorbitan monooleate Nutrition 0.000 description 5
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910001208 Crucible steel Inorganic materials 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- DLHONNLASJQAHX-UHFFFAOYSA-N aluminum;potassium;oxygen(2-);silicon(4+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[Al+3].[Si+4].[Si+4].[Si+4].[K+] DLHONNLASJQAHX-UHFFFAOYSA-N 0.000 description 2
- 229940092782 bentonite Drugs 0.000 description 2
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- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
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- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention relates to the technical field of casting, in particular to an environment-friendly efficient stripping sand mould coating for large-scale steel castings and a preparation method thereof, wherein the environment-friendly efficient stripping sand mould coating comprises a first layer of coating, a second layer of coating and a third layer of coating; the first layer of coating is the same as the second layer of coating, and comprises the following raw materials in parts by mass: 60 to 80 parts of refractory aggregate, 0.3 to 0.5 part of oxidized rosin resin, 0.8 to 1 part of phenolic resin, 30 to 40 parts of isopropanol and 1 to 8 parts of suspending agent; the third layer coating comprises the following raw materials in parts by mass: 30-50 parts of refractory aggregate, 2-4 parts of flatting agent, 15-40 parts of modified ceramic powder, 1-10 parts of suspending agent, 1-7 parts of binder, 1-2 parts of associative thickener, 1-3 parts of surfactant and 20-30 parts of carrier liquid. The coating disclosed by the invention has good fire resistance, heat conductivity, wear resistance and air permeability, is non-corrosive to castings, can be peeled off in a flaking way when the coating is peeled off in a later period, and has no dust emission.
Description
Technical Field
The invention relates to the technical field of casting, in particular to an environment-friendly efficient stripping sand mold coating for large-scale steel castings and a preparation method thereof.
Background
Casting paints are thin layers of refractory coating applied to the surface of the casting mold (core), varying from a few tenths of a millimeter to a few millimeters. It is a colloidal physical suspension dispersion system, and usually contains refractory aggregate, carrier, suspending agent, adhesive and auxiliary agent. Wherein the refractory aggregate is the basis of a coating material, suspended in the coating material by means of a suspending agent, and uniformly coated on the working surface of the casting core. After coating, the carrier liquid is volatilized and the adhesive dries the powder into a dense coating to protect the working surface. Casting coatings are required to have adequate fire resistance of aggregate and smooth surface quality as effective casting materials for shielding steel and sand molds. The coating typically requires at least three passes to achieve a sufficient coating thickness. For the water glass forming process, the water of the water-based paint or the shielding effect of the water-based paint on air water is poor, so that the contact of the water-based paint with the sand mold for the first time can negatively influence the strength of the sand mold, and air bubbles can be formed after the coating is dried. In addition, for large castings, it takes longer to dry with the aqueous coating, which, if used in its entirety, tends to affect the production schedule. However, if all the alcohol-based paint is used, the water-based paint has obvious advantages in terms of moisture isolation, drying and curing speeds compared with the water-based paint, but the sand mould of the large casting has a certain risk due to the ignition mode of all the sand moulds of the large casting, and the surface quality of the alcohol-based paint is not fine and smooth as the water-based paint, so that the surface of the casting is rough.
Heretofore, the applicant discloses in the patent with publication number of CN102000762B a combined coating process for water glass sand mould of large steel castings, the coating is divided into three layers of coating, the primer and the second layer are alcohol-based coating, the outermost layer is water-based coating, the baume degree of the third layer of coating is controlled, the coating process has strong adhesion to sand mould, high fire resistance, good leveling property and surface smoothness. However, with the development progress and continuous innovation of companies, the applicant finds that sand mold coating still has a plurality of problems to be solved in the casting process.
Graphite and zircon powder are commonly used for casting coating, and graphite can produce one deck protection film in the casting process, prevents to stick sand, can play certain peeling effect, but it very easily flies upward when peeling off, and the adhesion ability is strong, difficult clearance and clean. The peeling of the zircon powder coating layer also has dust emission phenomenon and is expensive. In CN104439049B "alcohol ceramic casting paint", potassium feldspar powder is used as cosolvent to combine with suspending agent, surfactant and other raw materialsThe prepared casting coating can enable a coating layer to flake off and has good sintering stripping characteristics. However, the cast steel has harsh conditions and high casting temperature, and the potassium feldspar is extremely easy to decompose into potassium mica and silicon dioxide, and K in the potassium mica 2 O has strong corrosiveness and oxidizing property, and is also combined with CO 2 K formed by the reaction 2 CO 3 Also has certain alkalinity, and when molten steel enters the casting cavity, iron is oxidized into Fe 3+ And Fe (Fe) 2+ The strength of the steel is affected, and certain corrosiveness is generated on the steel body, so that the cast steel and the adverse effects are caused.
Therefore, the preparation of the composite coating which is easy to peel, green and environment-friendly, has smooth surface, good sand-resisting capability, good fire resistance and air permeability and no corrosion to castings is urgent.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the environment-friendly efficient stripping sand mould coating for the large-scale steel castings and the preparation method thereof, wherein the sand mould coating has the advantages of fire resistance, high strength, good air permeability, easiness in stripping and no corrosion.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the invention provides an environment-friendly efficient stripping sand mold coating for large-scale steel castings, which comprises a first layer of coating, a second layer of coating and a third layer of coating; the first layer of coating is the same as the second layer of coating, and comprises the following raw materials in parts by mass: 60 to 80 parts of refractory aggregate, 0.3 to 0.5 part of oxidized rosin resin, 0.8 to 1 part of phenolic resin, 30 to 40 parts of isopropanol and 1 to 8 parts of suspending agent; the third layer coating comprises the following raw materials in parts by mass: 30-50 parts of refractory aggregate, 2-4 parts of flatting agent, 15-40 parts of modified ceramic powder, 1-10 parts of suspending agent, 1-7 parts of binder, 1-2 parts of associative thickener, 1-3 parts of surfactant and 20-30 parts of carrier liquid.
In some embodiments, the mass of suspending agent in the first layer of coating and the second layer of coating is 4-8% of the mass of refractory aggregate.
In some embodiments, the mass of the modified ceramic powder in the third layer coating is 60 to 70% of the mass of the refractory aggregate.
Preferably, in the third layer coating, the mass of the modified ceramic powder is 65% of the mass of the refractory aggregate.
The applicant has found unexpectedly that the addition of the modified ceramic powder to the coating can enhance the smoothness, fire resistance and wear resistance of the coating, and is green and dust-free in the post stripping process, which is attributed to the process of sintering the ceramic at high temperature during the preparation process, so that the ceramic structure is denser. However, the modified ceramic powder has the problem of large brittleness, and the application can prevent the coating layer from cracking to influence the quality of castings due to the impact force generated by molten steel pouring caused by the excessive brittleness after the coating layer is solidified by regulating and controlling the addition amount of the modified ceramic powder and the refractory aggregate; meanwhile, the problem of brittleness of the coating is utilized to prevent dust generation during coating peeling, and the problem of difficult peeling is solved, so that the influence on the environment is reduced.
In some embodiments, the mass of the suspending agent in the third layer coating is 6 to 10% of the total mass of the refractory aggregate and the modified ceramic powder.
Preferably, in the third layer of coating, the mass of the suspending agent is 8% of the total mass of the refractory aggregate and the modified ceramic powder.
The suspending agent can prevent solid particles in the system from agglomerating and settling, the condition of supernatant liquid appears, and the coating is coated more uniformly, and besides, the storage time of the coating can be prolonged. The suspension agent and the refractory aggregate can be uniformly dispersed in the system by regulating the proportion of the suspension agent to the total mass of the refractory aggregate and the modified ceramic powder, and the air permeability and the leveling property of the coating layer can be improved. If too much suspending agent is added, the air permeability and leveling property of the paint layer are poor, on one hand, the particles of the suspending agent are tiny and are easy to block in the pores of the paint layer, so that the air permeability is poor, on the other hand, too much suspending agent can generate more net structures, absorb more refractory aggregate and modified ceramic powder, so that the viscosity of the system is suddenly increased, and the leveling property is reduced; too little suspending agent can cause uneven dispersion of the system and reduced viscosity.
In some embodiments, the mass of the binder in the third layer coating is 4 to 6% of the total mass of the refractory aggregate and the modified ceramic powder.
Preferably, in the third layer coating, the mass of the binder is 5% of the total mass of the refractory aggregate and the modified ceramic powder.
The adhesive can firmly adhere the coating layer on the sand mold, and prevent the coating layer from falling off due to huge impact force and friction force generated by molten steel pouring, thereby improving the quality of castings. The viscosity of the system can be higher by regulating the proportion between the binder and the total mass of the refractory aggregate and the modified ceramic powder, and the excessive binder can cause the pores of the coating layer to be blocked. Resulting in deterioration of the air permeability of the paint layer.
In some embodiments, the refractory aggregate is one or more of quartz powder, bauxite, magnesia powder, and zircon powder; the leveling agent is one or more of polyvinyl butyral, pure acrylic acid and organic modified polysiloxane; the suspending agent is sodium bentonite; the associative thickener is one or more of TT-40 thickener, TT-90 thickener and TT-935 thickener; the surfactant is Tween 80; the binder is water glass; the carrier liquid is water.
Preferably, the refractory aggregate is zircon powder; the leveling agent is polyvinyl butyral; the associative thickener is TT-40 thickener.
The applicant found that although both sodium bentonite and lithium bentonite are excellent in suspension properties, the lithium bentonite occasionally runs in coating applications, causing defects in the flatness and thickness of the coating.
In some embodiments, the modified ceramic powder is a titania-doped alumina ceramic powder, and the modified ceramic powder has a particle size of 400 mesh or less.
The applicant finds that the performance of the alumina ceramic powder doped with titanium dioxide is more suitable for a sand mould coating system due to the strong impact property, good wear resistance, low brittleness and better stability of the alumina, but the brittleness is larger, so that the brittleness of the alumina can be changed by doping the titanium dioxide into the alumina, so that the brittleness of the alumina ceramic powder is more suitable for the application of the sand mould coating system, and the alumina ceramic powder doped with titanium dioxide also has the photocatalytic performance, so that the corrosion of a sand mould coating layer can be reduced, the surface of the coating layer is durable and smooth, the surface quality of a casting is improved, and the later polishing difficulty of the casting is reduced; in addition, the applicant prevents the leveling property of the coating system from being deteriorated due to the oversized particle size by controlling the particle size of the modified ceramic powder.
In some embodiments, the modified ceramic powder comprises the following raw materials in parts by mass: 80-90 parts of alpha-Al 2 O 3 8-10 parts of rutile TiO 2 2-6 parts of starch.
In the casting process, at the moment when molten steel is poured into the sand mould, a large amount of gas is generated by the casting mould, if the air permeability of the sand mould is poor, choking fire can occur, and casting defects such as air holes, uneven casting and the like can be generated on a large casting. According to the modified ceramic powder, the modified ceramic powder porosity can be increased by filling the starch into the raw materials for preparing the modified ceramic powder, so that the air permeability of the sand mould coating is increased, and the excessive starch can lead to the strength of the modified ceramic powder to be reduced and loosen although the air permeability of the coating is better.
In some embodiments, the method of preparing the modified ceramic powder comprises the steps of:
(1) alpha-Al 2 O 3 Rutile type TiO 2 Mixing with starch according to mass parts, placing in a planetary ball mill, wherein the rotating speed is 1000-2000 r/min, the ball milling time is 2-3 hours, and the particle size is 200-400 meshes;
(2) Pressing the ball-milled mixed powder into blocks or sheets, wherein the pressure of a film pressing machine is 180-200MPa;
(3) Calcining the pressed sheet or block in a microwave muffle furnace at 1600-1800 ℃ for 4-8 hours, naturally cooling to room temperature, and ball milling and sieving to obtain the modified ceramic powder.
Preferably, the preparation method of the modified ceramic powder comprises the following steps:
(1) alpha-Al 2 O 3 Rutile type TiO 2 Mixing with starch according to mass parts, placing in a planetary ball mill, wherein the rotating speed is 1500r/min, the ball milling time is 2.5 hours, and the particle size is 300 meshes;
(2) Pressing the ball-milled mixed powder into blocks or sheets, wherein the pressure of a film pressing machine is 190MPa;
(3) Calcining the pressed sheet or block in a microwave muffle furnace at 1700 ℃ for 6 hours, naturally cooling to 35-45 ℃, and ball-milling and sieving to obtain the modified ceramic powder.
According to the application, on one hand, the aluminum oxide, the titanium dioxide and the starch are mixed and pressed, so that the contact area between the components is larger, the higher the strength of the modified ceramic powder is, the more compact the structure is, and the strength and the wear resistance of the coating layer are also increased; on the other hand, the microwave calcining mode can save more calcining time than the conventional calcining mode, the calcining temperature is lower, and the structure compactness of the modified ceramic powder is better, the strength is higher, so that the strength and the wear resistance of the coating layer are increased.
The invention also provides a preparation method of the environment-friendly efficient stripping sand mold coating for the large-scale steel castings, which comprises the following steps: mixing the first layer of coating, the second layer of coating and the third layer of coating according to the mass ratio, stirring for 1-2 hours, then carrying out ultrasonic treatment for 30-40 minutes, and uniformly dispersing.
The invention also provides an application of the environment-friendly efficient stripping sand mold coating for large-scale steel castings, which comprises the following steps: and (3) spraying a first layer of coating to the inner wall of the sand mold, controlling the thickness to be 0.05-1 mm, spraying a second layer of coating after the coating is cured, controlling the thickness to be 0.1-0.15 mm, and spraying a third layer of coating after the coating is cured, and controlling the thickness to be 0.1-0.15 mm.
The applicant controls the dimensional accuracy and the surface quality of the casting by controlling the thickness of the coating layer, and the dimension of the casting is not easy to control due to the overlarge thickness, and the coating layer has an unprotected effect and causes the casting defect.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the invention, the modified ceramic powder is added into the sand mold coating, so that the air permeability, smoothness, strength and fire resistance of the coating can be enhanced, and in addition, the sand mold coating has good heat conduction performance, can accelerate the emission of temperature in a cavity, and can improve the solidification speed of castings.
(2) The modified ceramic powder of the invention is prepared from TiO 2 ，Al 2 O 3 The modified ceramic powder is formed by mixing starch according to specific parts by mass, pressing and sintering, and the brittleness of the modified ceramic powder can be more suitable for the application of sand mould coating by regulating and controlling the content of each component, and the modified ceramic powder has good air permeability and no corrosion to castings, and meanwhile, the surface of the sand mould coating can be kept smooth for a long time, the surface quality of the castings is improved, and the polishing difficulty is reduced.
(3) The invention utilizes the brittleness of ceramics to be easier to be scattered into pieces when the sand mould coating layer is stripped, and has no dust pollution to the environment.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The coatings prepared in the following examples and comparative examples include: a first layer of coating, a second layer of coating and a third layer of coating.
The application of the coatings prepared in each example and comparative example comprises the following steps: and (3) spraying a first layer of coating to the inner wall of the sand mold, controlling the thickness to be 0.08mm, spraying a second layer of coating after the coating is cured, controlling the thickness to be 0.13mm, and spraying a third layer of coating after the coating is cured, and controlling the thickness to be 0.13mm.
In the following examples and comparative examples, the phenolic resin was KR80 phenolic resin, the particle size of sodium bentonite was 300 mesh, the particle size of zircon powder was 325 mesh, and the polyvinyl butyral number average molecular weight was 40000.
Preparation example 1
The preparation method of the alumina ceramic powder doped with titanium dioxide comprises the following steps:
(1) 85 parts of alpha-Al 2 O 3 4 parts of rutile type TiO 2 Mixing with 9 parts of starch, placing into planetary ball mill with rotation speed of 1500r/min, and ball milling2.5 hours, and the grain size is 300 meshes;
(2) Pressing the ball-milled mixed powder into blocks or sheets, wherein the pressure of a film pressing machine is 190MPa;
(3) Calcining the pressed sheet or block in a microwave muffle furnace at 1700 ℃ for 6 hours, naturally cooling to room temperature, ball-milling, and sieving with 400-mesh sieve to obtain the modified ceramic powder.
Preparation example 2
The specific embodiment of the titania-doped alumina ceramic powder was the same as in preparation example 1, except that no starch was added.
Example 1
An environment-friendly high-efficiency stripping sand mold coating for large-scale steel castings, comprising: a first layer of coating, a second layer of coating and a third layer of coating.
The first layer of coating and the second layer of coating comprise the following raw materials in parts by mass: 70 parts of zircon powder, 0.4 part of oxidized rosin resin, 0.9 part of phenolic resin, 4 parts of sodium bentonite and 35 parts of isopropanol; the third layer comprises the following raw materials in parts by mass: 40 parts of zircon powder, 3 parts of polyvinyl butyral, 1.5 parts of TT-40 thickener, 2 parts of Tween 80, 5.3 parts of sodium bentonite, 3.3 parts of water glass, 26 parts of alumina ceramic powder doped with titanium dioxide and 20-30 parts of water.
Wherein, alumina ceramic powder doped with titanium dioxide is prepared from preparation example 1.
The preparation method of the environment-friendly efficient stripping sand mold coating for the large-scale steel castings comprises the following steps: mixing the first layer of coating, the second layer of coating and the third layer of coating according to the mass ratio, stirring for 1.5 hours, performing ultrasonic treatment for 35 minutes, and uniformly dispersing.
Example 2
An environment-friendly high-efficiency stripping sand mold coating for large-scale steel castings, comprising: a first layer of coating, a second layer of coating and a third layer of coating.
The first layer of coating and the second layer of coating comprise the following raw materials in parts by mass: 60 parts of zircon powder, 0.3 part of oxidized rosin resin, 0.8 part of phenolic resin, 2 parts of sodium bentonite and 30 parts of isopropanol; the third layer comprises the following raw materials in parts by mass: 50 parts of zircon powder, 4 parts of polyvinyl butyral, 2 parts of TT-40 thickener, 3 parts of Tween 80, 8.5 parts of sodium bentonite, 5.1 parts of water glass, 35 parts of alumina ceramic powder doped with titanium dioxide and 30 parts of water.
Wherein, alumina ceramic powder doped with titanium dioxide is prepared from preparation example 1.
The preparation method of the environment-friendly efficient stripping sand mold coating for the large-scale steel castings comprises the following steps: mixing the first layer of coating, the second layer of coating and the third layer of coating according to the mass ratio, stirring for 2 hours, performing ultrasonic treatment for 40 minutes, and uniformly dispersing.
Example 3
An environment-friendly high-efficiency stripping sand mold coating for large-scale steel castings, comprising: a first layer of coating, a second layer of coating and a third layer of coating.
The first layer of coating and the second layer of coating comprise the following raw materials in parts by mass: 65 parts of zircon powder, 0.4 part of oxidized rosin resin, 0.9 part of phenolic resin, 3 parts of sodium bentonite and 32 parts of isopropanol; the third layer comprises the following raw materials in parts by mass: 30 parts of zircon powder, 2 parts of polyvinyl butyral, 1 part of TT-40 thickener, 1 part of Tween 80, 2.9 parts of sodium bentonite, 1.9 parts of water glass, 18 parts of alumina ceramic powder doped with titanium dioxide and 20 parts of water.
Wherein, alumina ceramic powder doped with titanium dioxide is prepared from preparation example 1.
The preparation method of the environment-friendly efficient stripping sand mold coating for the large-scale steel castings comprises the following steps: mixing the first layer of coating, the second layer of coating and the third layer of coating according to the mass ratio, stirring for 1 hour, performing ultrasonic treatment for 30 minutes, and uniformly dispersing.
Example 4
An environment-friendly high-efficiency stripping sand mold coating for large-scale steel castings, comprising: a first layer of coating, a second layer of coating and a third layer of coating.
The first layer of coating and the second layer of coating comprise the following raw materials in parts by mass: 80 parts of zircon powder, 0.5 part of oxidized rosin resin, 1 part of phenolic resin, 6 parts of sodium bentonite and 40 parts of isopropanol; the third layer comprises the following raw materials in parts by mass: 45 parts of zircon powder, 3 parts of polyvinyl butyral, 1.5 parts of TT-40 thickener, 2 parts of Tween 80, 6 parts of sodium bentonite, 4 parts of water glass, 27 parts of alumina ceramic powder doped with titanium dioxide and 30 parts of water.
Wherein, alumina ceramic powder doped with titanium dioxide is prepared from preparation example 1.
The preparation method of the environment-friendly efficient stripping sand mold coating for the large-scale steel castings comprises the following steps: mixing the first layer of coating, the second layer of coating and the third layer of coating according to the mass ratio, stirring for 1.5 hours, performing ultrasonic treatment for 35 minutes, and uniformly dispersing.
Example 5
The embodiment provides a preparation method of an environment-friendly efficient stripping sand mold coating for a large steel casting, which is similar to the embodiment 1 in specific implementation mode, and is characterized in that 36 parts of alumina ceramic powder doped with titanium dioxide is used in the third layer of coating.
Example 6
The embodiment provides a preparation method of an environment-friendly efficient stripping sand mold coating for a large steel casting, which is similar to the embodiment 1 in specific implementation mode, and is characterized in that 12 parts of alumina ceramic powder doped with titanium dioxide is used in the third layer of coating.
Example 7
The embodiment provides a preparation method of an environment-friendly efficient stripping sand mold coating for large-scale steel castings, and the specific implementation mode is the same as that of the embodiment 1, wherein the third layer coating uses commercial alumina ceramic powder with equal mass to replace the alumina ceramic powder doped with titanium dioxide.
Example 8
The embodiment provides a preparation method of an environment-friendly efficient stripping sand mold coating for large-scale steel castings, which is different from the embodiment 1 in that 10 parts of sodium bentonite is used in the third layer coating.
Example 9
The embodiment provides a preparation method of an environment-friendly efficient stripping sand mold coating for large-scale steel castings, which is different from the embodiment 1 in that the water glass in the third layer coating is 7 parts.
Example 10
The embodiment provides a preparation method of an environment-friendly efficient stripping sand mold coating for large-scale steel castings, and the specific implementation mode is the same as that of the embodiment 1, except that alumina ceramic powder doped with titanium dioxide is prepared from the preparation example 2.
Comparative example 1
The comparative example provides a method for preparing a sand mold coating, and the specific embodiment is the same as example 1, except that the titanium dioxide-doped alumina ceramic powder is not added in the third layer coating.
Performance test:
the sand mold coatings prepared in examples 1 to 10 and comparative example 1 were tested according to the method in JB/T9226-2008 "coating for sand mold casting", the leveling property of the coating was tested according to the standard of GB1750-89 (79) method for measuring leveling property of the coating, the abrasion resistance of the coating was tested according to the standard of ISO 1518-1 "measurement of scratch resistance of colored paint and varnish", the impact toughness of the coating was measured according to the standard of GB/T4742-1984 "method for measuring impact toughness of domestic ceramics", and the test results are shown in Table 1.
TABLE 1
As can be seen from Table 1, the environment-friendly and efficient stripping sand mold coating for large-scale steel castings prepared in examples 1 to 4 has high fire resistance, good air permeability, high wear resistance and good heat dissipation. In the embodiment 5, the proportion of the modified ceramic powder to the refractory aggregate is changed, so that the content of the modified ceramic powder is increased, the wear resistance of the coating is slightly improved, but the suspension rate and impact toughness of the coating are slightly reduced, the instantaneous coating part irrigated by molten steel is cracked, the surface of a casting is not smooth and flat, and the casting needs to be polished; in the embodiment 6, the proportion of the modified ceramic powder and the refractory aggregate is changed, the content of the ceramic powder is reduced, so that the impact toughness and the suspension rate of the coating are slightly improved, but the wear resistance and the heat dissipation performance are reduced, dust is generated when the coating is stripped, and the environment is polluted; example 7 because of the use of commercially available mono-alumina ceramic instead of titania-doped alumina ceramic powder, the brittleness of the modified ceramic powder is greatly increased, resulting in reduced impact toughness of the coating, cracking of the coating during molten steel casting, and uneven casting surface, requiring polishing; in the embodiment 8, the suspension performance of the coating is obviously enhanced due to the change of the proportion of the suspending agent to the mass sum of the refractory aggregate and the ceramic, but the suspending agent blocks the pores of the coating, so that the air permeability of the coating is poor, the casting is severely recessed, and the use is influenced; example 9 the binder was used to block the paint pores due to the varying proportions of binder to refractory aggregate and ceramic mass, resulting in poor paint breathability and severe sagging of the castings to effect use; in the embodiment 10, as no starch is added in the preparation process of the modified ceramic powder, the air permeability and the heat conductivity of the coating are slightly reduced, and the surface part of the casting is slightly uneven, so that the use is not affected, but the casting needs to be polished smoothly; in comparative example 1, the suspension rate and impact toughness of the coating are slightly improved due to the fact that the titanium dioxide-doped alumina ceramic powder is not added into the coating, but the wear resistance, the heat conductivity and the fire resistance of the coating are all reduced, and in addition, a large amount of dust is generated in the process of stripping the coating, so that the workshop environment is seriously influenced. The detection result shows that the environment-friendly efficient stripping sand mould coating for the large-scale steel castings, which is prepared by the invention, has higher fire resistance, air permeability, heat conductivity, wear resistance and heat dissipation, has smooth casting surface and no sand sticking phenomenon, can be stripped in a later coating stripping process, and has no dust emission.
Finally, it should be noted that the above-mentioned embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications and equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, and all such modifications and equivalents are intended to be encompassed in the scope of the claims of the present invention.
Claims (10)
1. The environment-friendly efficient stripping sand mold coating for the large-scale steel castings is characterized by comprising a first layer of coating, a second layer of coating and a third layer of coating; the first layer of coating is the same as the second layer of coating, and comprises the following raw materials in parts by mass: 60 to 80 parts of refractory aggregate, 0.3 to 0.5 part of oxidized rosin resin, 0.8 to 1 part of phenolic resin, 30 to 40 parts of isopropanol and 1 to 8 parts of suspending agent; the third layer coating comprises the following raw materials in parts by mass: 30-50 parts of refractory aggregate, 2-4 parts of flatting agent, 15-40 parts of modified ceramic powder, 1-10 parts of suspending agent, 1-7 parts of binder, 1-2 parts of associative thickener, 1-3 parts of surfactant and 20-30 parts of carrier liquid.
2. The environment-friendly efficient stripping sand mold coating for large steel castings, according to claim 1, wherein the mass of the suspending agent in the first layer of coating and the second layer of coating is 4-8% of that of refractory aggregate.
3. The environment-friendly efficient stripping sand mold coating for large steel castings, according to claim 1, wherein the mass of the modified ceramic powder in the third layer of coating is 60-70% of the mass of the refractory aggregate.
4. The environment-friendly efficient stripping sand mold coating for large steel castings, according to claim 1, wherein the mass of the suspending agent in the third layer of coating is 6-10% of the total mass of refractory aggregate and modified ceramic powder.
5. The environment-friendly efficient stripping sand mold coating for large steel castings, according to claim 1, wherein the mass of the binder in the third layer of coating is 4-6% of the total mass of refractory aggregate and modified ceramic powder.
6. The environment-friendly high-efficiency stripping sand mold coating for large steel castings, according to claim 1, wherein in the third layer of coating, the modified ceramic powder is alumina ceramic powder doped with titanium dioxide, and the granularity of the modified ceramic powder is less than or equal to 400 meshes.
7. The environment-friendly efficient stripping sand mold coating for large-scale steel castings, which is disclosed in claim 1, is characterized in that the modified ceramic powder comprises the following raw materials in parts by mass: 80-90 parts of alpha-Al 2 O 3 8-10 parts of rutile TiO 2 2-6 parts of starch.
8. The environment-friendly efficient stripping sand mold coating for large-scale steel castings, according to claim 1, is characterized in that the preparation method of the modified ceramic powder comprises the following steps:
(1) alpha-Al 2 O 3 Rutile type TiO 2 Mixing and ball milling with starch according to the mass portion, wherein the rotating speed is 1000-2000 r/min, the ball milling time is 2-3 hours, and the grain diameter is 200-400 meshes;
(2) Pressing the ball-milled mixed powder into blocks or sheets, wherein the pressure of a film pressing machine is 180-200MPa;
(3) Calcining the pressed block or sheet in a microwave muffle furnace at 1600-1800 ℃ for 4-8 hours, naturally cooling to room temperature, ball milling and sieving to obtain the modified ceramic powder.
9. A method for preparing the environment-friendly high-efficiency stripping sand mold coating for large-scale steel castings according to any one of claims 1 to 8, which is characterized by comprising the following steps: mixing the first layer of coating, the second layer of coating and the third layer of coating according to the mass ratio, stirring for 1-2 hours, then carrying out ultrasonic treatment for 30-40 minutes, and uniformly dispersing.
10. An application of the environment-friendly efficient stripping sand mould coating for large-scale steel castings according to any one of claims 1 to 8, which is characterized by comprising the following steps: and (3) spraying a first layer of coating to the inner wall of the sand mold, controlling the thickness to be 0.05-1 mm, spraying a second layer of coating after the coating is cured, controlling the thickness to be 0.1-0.15 mm, and spraying a third layer of coating after the coating is cured, and controlling the thickness to be 0.1-0.15 mm.
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