JP2004068045A - Zinc-based alloy and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zinc-based alloy having a surface layer to which desired strength, hardness and heat resistance are reliably imparted, along with having superior workability. <P>SOLUTION: A die 10 has an alloy layer 14 harder than a base layer 12 provided on the surface of the base layer 12. The alloy layer 14 has an iron-based alloy layer 16 superior in a melting point, strength, hardness, and heat resistance provided on the surface side, and a diffusion layer 18 provided between the above iron-based alloy layer 16 and the base layer 12. The diffusion layer 18 has, for instance, a brass layer containing copper and zinc, and has a content ratio gradually changing in the above diffusion layer 18. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a zinc-based alloy having a surface layer having an alloy layer harder than a base layer, and a method for producing the same.
[0002]
[Prior art]
Normally, zinc-based alloys such as a Zn-Al-Sn-based alloy have a low melting point, a slower oxidation than aluminum, and a lower strength and hardness. For this reason, a zinc-based alloy is used as a casting material, and in addition to a trial mold, a key or key cylinder having a complicated shape is manufactured.
[0003]
However, it has been pointed out that since the strength and hardness of the zinc-based alloy are low, the durability of cast products such as dies and keys is low and uneconomical. Therefore, in order to harden the surface of a zinc-based alloy, for example, a manufacturing method disclosed in Japanese Patent No. 2832224 is known.
[0004]
In this prior art, when performing electroless nickel plating directly on the surface of a mold made of a zinc-based alloy, the mold is immersed in an electroless nickel plating solution containing an organic acid nickel salt or the like. It is stated that, since the nickel coating is applied directly to the zinc-based alloy, the coating does not peel off, and is dense and free from cracks, so that the wear resistance and corrosion resistance are improved.
[0005]
[Problems to be solved by the invention]
However, in the above prior art, only the plating layer is provided on the surface of the zinc-based alloy, and the hardened layer (plating layer) is limited to only the surface layer. As a result, there is a problem that sufficient strength and heat resistance cannot be imparted to the surface layer of the zinc-based alloy.
[0006]
The present invention solves this kind of problem, and provides a zinc-based alloy that is excellent in workability and can reliably impart desired strength, hardness and heat resistance to a surface layer portion, and a method for producing the same. The purpose is to:
[0007]
[Means for Solving the Problems]
In the zinc-based alloy according to the present invention, an alloy layer harder than the base layer is formed on the surface layer, and the alloy layer has an iron-based alloy layer provided on the surface side, and the iron-based alloy layer and the base layer. And a diffusion layer containing at least one of copper and manganese and diffused into the base metal.
[0008]
Therefore, since the iron-based alloy layer is provided on the surface side, the melting point, strength, hardness and heat resistance of the surface actually used are considerably higher than that of the base metal zinc or zinc alloy, and the wear resistance is high. Thus, physical properties such as heat resistance and impact resistance can be reliably improved. Moreover, a diffusion layer is provided as an intermediate layer between the surface layer and the mother layer, and this diffusion layer is made of, for example, brass containing copper and zinc. Therefore, the melting point, strength, hardness and heat resistance are improved as compared with the base metal. At this time, by gradually changing the component ratio in the diffusion layer, there is no interface, and peeling and stress concentration due to a difference in thermal expansion can be effectively prevented.
[0009]
In addition, since the base metal is a Zn-Al-Sn-based alloy, it has a low melting point, is easily formed by casting, and has excellent workability. Thereby, it is favorably used as a mold material for casting or resin molding having a complicated shape.
[0010]
Further, the iron-based alloy layer is provided in a range of 0.5 mm to 1.5 mm inside from the surface, and the diffusion layer is provided in a range of 0.5 mm to 30 mm inside the iron-based alloy layer. ing. If the iron-based alloy layer is less than 0.5 mm, the effect of improving the physical properties cannot be obtained, while if it exceeds 1.5 mm, the workability is reduced. If the thickness of the diffusion layer is less than 0.5 mm, the effect of improving the physical properties cannot be obtained. On the other hand, if it exceeds 30 mm, a long time is required for diffusion, and the efficiency of the manufacturing process cannot be improved.
[0011]
Still further, in the method for producing a zinc-based alloy according to the present invention, after processing the base metal of the zinc-based alloy into a predetermined shape, at least a part of the base metal contains at least one of copper and manganese. The first powder to be applied and the second powder of the iron-based alloy are sequentially applied. Next, the portion of the base metal to which the first and second powders have been applied is heated under an inert atmosphere. Therefore, a zinc-based alloy having higher strength and higher heat resistance than the base layer can be reliably obtained as the surface layer, and can be favorably used for various parts such as a mold.
[0012]
The above zinc-based alloy will be described in more detail. Since the base metal is mainly zinc (Zn), the surface and the vicinity of the surface can be made of brass. Brass is an alloy of copper (Cu) and zinc, has a melting point, strength, and hardness that are at least twice that of zinc, and also has high corrosion resistance.
[0013]
Further, copper is a powder metallurgy binder for iron (Fe), cobalt (Co) or nickel (Ni). For this reason, the outermost layer of the zinc-based alloy can be composed of an iron-based metal or an iron-based alloy layer that is an alloy composition thereof, and a diffusion layer that is a brass structure is provided, and the brass structure is directed toward the inside. It is possible to configure so that it gradually decreases to become a zinc alloy (base metal). That is, it is possible to provide a zinc-based alloy that can cover a zinc alloy with a thick shell that is strong and has high heat resistance and that can be used for a wide variety of applications.
[0014]
In addition, brass and iron-based alloys have a smaller thermal expansion than zinc and zinc alloys. For this reason, in a film treatment such as plating, a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or anodization, the film thickness becomes about several tens μm to 100 μm. And cracks occur.
[0015]
On the other hand, in the present invention, the iron-based alloy layer is provided in a range of 0.5 mm to 1.5 mm inside from the surface, and the diffusion layer is 0.5 mm to 1.5 mm inside from the iron-based alloy layer. It is provided within a range of 30 mm. Thereby, it does not break due to the concentration of stress acting on the dissimilar material under utilization of the heat cycle, and can withstand repeated use.
[0016]
Moreover, the diffusion layer continuously changes from the iron-based alloy layer, which is the surface layer, toward the mother layer, and the changed layer has a thickness of 0.5 mm to 30 mm. Therefore, the fatigue due to the repetitive action of heat becomes extremely small, and the heat conduction, density and elastic modulus change continuously, so that the fatigue limit is drastically improved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic cross-sectional view of a mold 10 made of a zinc-based alloy according to an embodiment of the present invention.
[0018]
The mold 10 has a base layer 12 and an alloy layer 14 that is harder than the base layer 12 formed on the surface. The alloy layer 14 is provided with an iron-based alloy layer 16 on the surface side, and a diffusion layer 18 is provided between the iron-based alloy layer 16 and the mother layer 12.
[0019]
The base metal forming the base layer 12 is zinc or a zinc alloy, and specifically, Zn, Zn—Al, Zn—Sn, or a Zn—Al—Sn-based alloy is used. The iron-based alloy layer 16 is made of iron (Fe), nickel (Ni), or cobalt (Co), and has a thickness H1 set from 0.5 mm to 1.5 mm from the surface toward the inside. You.
[0020]
The diffusion layer 18 contains at least one of copper (Cu) and manganese (Mn). On the iron-based alloy layer 16 side, Zn-Cu, Zn-Mn-Cu, Zn-Al-Cu, Zn-Al-Cu-Mn, Zn-Sn-Cu, Zn-Sn-Cu-Mn, Zn-Sn A brass layer selected from -Al-Cu or Zn-Sn-Al-Mn-Cu is provided. Inside the brass layer, a Mn alloy layer selected from Zn-Mn, Zn-Sn-Mn, Zn-Al-Mn, or Zn-Al-Sn-Mn is provided. The thickness H2 of the diffusion layer 18 is set within a range of 0.5 mm to 30 mm inward from the iron-based alloy layer 16.
[0021]
A method for manufacturing the thus configured mold 10 will be described below with reference to the flowchart shown in FIG. 2 and the process chart shown in FIG.
[0022]
First, as shown in FIG. 3, a base material 20 made of zinc or a zinc alloy is prepared, and the base material 20 is processed by a processing machine 22 (step S1). For this reason, the processing surface 24 corresponding to the cavity is formed on the base material 20.
[0023]
Next, the first powder 26 is applied to the processing surface 24 via the first application material 25a (Step S2). The first powder 26 includes at least one kind of copper or manganese, for example, copper and manganese mixed at a ratio of 4: 6 to 6: 4. Further, the second powder 28 is applied on the first powder 26 via the second application material 25b (Step S3). The second powder 28 is an alloy powder based on an iron-based metal.
[0024]
The base material 20 to which the first and second powders 26 and 28 have been applied is arranged in a heating device 30. The heating device 30 includes a heating source 32 such as a burner or a heater, and the base material 20 is heat-treated in the heating device 30 under an inert atmosphere, for example, a nitrogen gas (N ₂ gas) atmosphere ( Step S4). As a result, the mold 10 in which the alloy layer 14 harder than the base layer 12 is provided on the surface layer is obtained. The mold 10 has been subjected to a finishing treatment such as a surface polishing treatment (step S5).
[0025]
In this case, in the present embodiment, the alloy layer 14 is provided on the surface of the base layer 12, and the alloy layer 14 includes the iron-based alloy layer 16 and the diffusion layer 18. For this reason, the iron-based alloy layer 16 is provided on the surface layer of the mold 10, and the melting point, strength, hardness and heat resistance of the surface actually used are considerably higher than that of zinc or a zinc alloy. Thus, physical properties such as wear resistance, heat resistance and impact resistance are reliably improved.
[0026]
Moreover, a diffusion layer 18 is provided as an intermediate layer between the iron-based alloy layer 16 and the mother layer 12, and the diffusion layer 18 is made of, for example, a brass layer containing copper and zinc. Therefore, the diffusion layer 18 has improved melting point, strength, hardness, and heat resistance as compared with zinc or zinc alloy as the base metal.
[0027]
At this time, by gradually changing the component ratio in the diffusion layer 18, there is no interface, and peeling and stress concentration due to a difference in thermal expansion can be effectively prevented. This makes it possible to use the mold 10 satisfactorily over a long period of time, and has an effect of being extremely economical.
[0028]
The iron-based alloy layer 16 has a thickness H1 within the range of 0.5 mm to 1.5 mm from the surface to the inside, and the diffusion layer 18 has a thickness H2 inside the iron-based alloy layer 16. It is provided in the range of 0.5 mm to 30 mm. For this reason, it is possible to reliably prevent the occurrence of cracks, cracks, and the like, particularly under the use of a heat cycle, as compared with the case where the base layer 12 is subjected to a coating treatment such as plating, CVD, PVD, or anodic oxidation.
[0029]
Note that if the thickness H1 of the iron-based alloy layer 16 is less than 0.5 mm, the effect of improving the physical properties cannot be obtained, while if the thickness H1 exceeds 1.5 mm, the workability is reduced. When the thickness H2 of the diffusion layer 18 is less than 0.5 mm, the effect of improving the physical properties cannot be obtained. On the other hand, when the thickness H2 exceeds 30 mm, a long time is required for diffusion, and the efficiency of the manufacturing process is increased. I can't.
[0030]
【Example】
As a zinc alloy, a base material 20 made of a Zn-Al-Sn-based alloy (ZAS material) that is frequently used in a simple type and a test type was prepared. The surface of the base material 20 was processed to form a processing surface 24 corresponding to the cavity, and an oil film on the processing surface 24 was removed for cleaning.
[0031]
An oxide film is present on the processed surface 24, and the processed surface 24 from which the oxide film has been removed is coated with a Cu-Mn powder (composition ratio 5: 2) in a solvent containing an acrylic resin and cellulose nitrate. It was applied in a thickness of 1.5 mm. Further, Cu-Mn-Fe-Al powder (composition ratio: 20: 15: 64: 1) was dispersed in an organic solvent containing an acrylic resin, and applied on the Cu-Mn powder in a thickness of 2 mm.
[0032]
Next, the processed surface 24 of the base material 20 on which the above-described application was performed was heated by a burner using propane and oxygen for 20 minutes. Thereby, the applied metal diffused into the base metal (Zn-Al-Sn-based alloy).
[0033]
Thereafter, the base material 20 was processed to obtain a test mold having a size of 300 mm × 300 mm × 80 mm and a maximum cavity depth of 30 mm. In addition, the thickness of the coating film was reduced to 0.9 mm to 1.1 mm after heating.
[0034]
In this case, the outermost surface of the powder was oxidized by the burner heating, but the thickness of the oxidized area was about 0.2 mm or less. Was.
[0035]
The internal structure of the base material 20 from the processed surface 24 was observed after performing an etching process for 45 seconds using 10% NaOH. At that time, the thickness of the yellow layer which was a brass layer was 7 mm to 9 mm, and the alloy diffusion layer thereafter changed from the surface to about 27 mm. In this change, the crystals changed from dendrites to cubic crystals, equiaxed crystals, and the like, and were clearly recognized.
[0036]
On the other hand, in the X-ray observation, the surface of the processed surface 24 was in a metallic luster region, where Fe was 94% and Cu was 5%. In a region 1 mm inward from the surface, Cu was 50% and Zn was 50%, and in a region further 5 mm inward, Cu was 25%, Mn was 14%, and Zn was 50%.
[0037]
In a region 10 mm inside from the surface, Cu is 8%, Mn is 10%, and Zn is 76%. In a region 20 mm inside, Cu is 4%, Mn is 5%, and Zn is 82%. %, And a further 30 mm region inside was a Zn-Al-Sn-based alloy composition.
[0038]
Therefore, heat resistance and impact tests were performed using a processed product not subjected to powder treatment (hereinafter, referred to as a comparative type) and the test type described above. Specifically, the cavity was placed in a furnace heated to 200 ° C., held for 10 minutes, and then dropped into water having a water temperature of 20 ° C. This was repeated to observe the occurrence of cracks. As a result, in the comparative mold, cracks occurred in the cavity corners of the mold in 18 cycles, and damage was clearly observed at the 28th cycle.
[0039]
On the other hand, in the experimental type, no crack was observed at the corner even after 320 cycles, and a minute crack occurred at the 374th cycle. As a result, the effect that the heat check resistance of the test type was considerably improved as compared with the comparative type was obtained.
[0040]
【The invention's effect】
In the zinc-based alloy according to the present invention, since the iron-based alloy layer is provided on the surface layer of zinc or zinc alloy, the melting point, strength, hardness and heat resistance of the surface actually used are considerably higher than that of the base metal. As a result, physical properties such as wear resistance, heat resistance and impact resistance are reliably improved. Moreover, a diffusion layer is provided as an intermediate layer between the surface layer and the mother layer, and this diffusion layer is made of, for example, brass containing copper and zinc. For this reason, melting | fusing point, strength, hardness, and heat resistance improve effectively compared with zinc or zinc alloy which is a base metal.
[0041]
In the method for producing a zinc-based alloy according to the present invention, after processing the base metal of the zinc-based alloy into a predetermined shape, at least a part of the base metal contains at least one of copper and manganese. The first powder and the second powder of the iron-based alloy are sequentially applied. Next, the portion of the base metal to which the first and second powders are applied is heated under an inert atmosphere. For this reason, a zinc-based alloy having higher strength and higher heat resistance than the base layer can be reliably obtained on the surface layer, and can be favorably used for various parts such as dies.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a mold made of a zinc-based alloy according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating a method for manufacturing the mold.
FIG. 3 is a process chart for manufacturing the mold.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Die 12 ... Base layer 14 ... Alloy layer 16 ... Iron-base alloy layer 18 ... Diffusion layer 20 ... Base material 22 ... Processing machine 24 ... Processing surfaces 26 and 28 ... Powder 30 ... Heating device 32 ... Heating source

Claims (4)

A zinc-based alloy in which a harder alloy layer is formed on the surface than the base layer,
The alloy layer is provided with an iron-based alloy layer on the surface side,
A zinc-based alloy, wherein a diffusion layer containing at least one of copper and manganese and diffused into a base metal is provided between the iron-based alloy layer and the base layer. The zinc-based alloy according to claim 1, wherein the base metal is a Zn-Al-Sn-based alloy. The zinc-based alloy according to claim 1, wherein the iron-based alloy layer is provided within a range of 0.5 mm to 1.5 mm inside from the surface,
The zinc-based alloy, wherein the diffusion layer is provided within a range of 0.5 mm to 30 mm inside the iron-based alloy layer. A method for producing a zinc-based alloy in which a harder alloy layer is formed on a surface layer than a base layer,
Processing the base metal of the zinc-based alloy into a predetermined shape,
A step of applying a first powder containing at least one of copper and manganese to at least a part of the base metal;
Applying a second powder of an iron-based alloy to the coating layer to which the first powder has been applied;
Heating the portion of the base metal coated with the first and second powders under an inert atmosphere;
A method for producing a zinc-based alloy, comprising:

Images