Process method for high-alloy densification infiltrated layer on surface of powder metallurgy component

Abstract

The invention relates to the technical field of powder metallurgy, and particularly discloses a process method for a high-alloy densified infiltrated layer on the surface of a powder metallurgy component, which comprises the following steps: raw material preparation, coating and drying, and sintering treatment. According to the method, after alloy powder coating the surface of the powder metallurgy component is melted at high temperature, the alloy powder is sucked into the surface layer of the component through capillary pore force of powder metallurgy pores, the loose surface layer of the powder metallurgy component can be converted into a high-performance alloy compact layer, and compared with a base body, the porosity of the alloy layer is obviously reduced; alloy elements such as nickel, copper, manganese and the like are obviously increased, so that the alloy has higher hardness, wear resistance, corrosion resistance and higher mechanical property.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a process for forming a high alloy densified diffusion layer on the surface of a powder metallurgy part. Background Art

[0002] With the continuous development of industrial technology, the requirements for material performance are also increasing. As an important engineering material, powder metallurgy parts are widely used in automobiles, power tools, engineering machinery and other fields.

[0003] Powder metallurgy technology is a technology that uses metal powder or non-metal powder as raw material to prepare materials or parts through processes such as forming and sintering. However, the surface hardness, wear resistance, corrosion resistance, mechanical strength and other properties of traditional powder metallurgy parts are limited, and it is difficult to meet the needs of certain high-performance application scenarios. Therefore, a process method for high-alloy densification layer on the surface of powder metallurgy parts is developed. Summary of the invention

[0004] The object of the present invention is to provide a process for forming a high alloy densified layer on the surface of a powder metallurgy part, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A process for forming a high alloy densified layer on the surface of a powder metallurgy part, comprising the following steps:

[0007] S1. Selecting an alloy powder having high mutual solubility with a powder metallurgy substrate and fully stirring and mixing the alloy powder with an organic resin liquid to obtain a mixed slurry;

[0008] S2, coating and drying: coating the prepared powder slurry on the surface of the powder metallurgy substrate, and then drying it;

[0009] S3. Sintering treatment: placing the coated and dried powder metallurgy substrate in a sintering furnace for sintering to form a dense alloyed infiltration layer on the surface of the part, thereby obtaining a powder metallurgy part with a high alloy densified infiltration layer on the surface.

[0010] Preferably, in S1, the melting point of the alloy powder is at least 200° C. lower than that of the powder metallurgy substrate, and the particle size of the alloy powder is -325 mesh.

[0011] Preferably, in S2, the drying process is carried out by air drying or drying in an oven.

[0012] Preferably, in S3, the sintering temperature is set to be 50° C. or higher than the melting point of the alloy powder, and the high temperature period is not less than 5 minutes.

[0013] Preferably, in S3, the alloy powder coated on the surface is melted, and the molten alloy liquid is sucked into the surface layer of the part by the capillary force of the pores of the powder metallurgy part, and continuously diffuses into the matrix.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) After the alloy powder infiltration treatment, a high-performance dense alloy layer can be formed on the surface of the powder metallurgy part. The porosity of the alloy layer is significantly reduced compared to the substrate, while the alloy elements such as nickel, copper, and manganese are significantly increased, which makes it have higher hardness, wear resistance, corrosion resistance and higher mechanical properties.

[0016] (2) During the infiltration process, the alloy elements not only penetrate into the matrix, but also continue to diffuse into the base material, and merge with the base material on the surface of the product. Therefore, there will be no problems such as surface detachment during the use of subsequent parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Embodiment 1:

[0020] See also Figure 1 As shown, a process for forming a high alloy densified layer on the surface of a powder metallurgy part comprises the following steps:

[0021] S1. Raw material preparation: The material of the powder metallurgy parts in this case is F0008. The selected alloy powder composition is nickel-based pre-alloyed powder, with a composition of 23% manganese, 7% silicon, 4.5% copper, and the rest is nickel. The organic liquid is a special resin liquid and trimethylbenzene solution;

[0022] Use a high-speed disperser to mechanically mix the special resin liquid and trimethylbenzene for 10 minutes, then gradually add the alloy powder while dispersing it with the high-speed disperser. After it is completely added, disperse it for another 20 minutes. Finally, the mixing ratio of the alloy powder, resin liquid and trimethylbenzene solution is 8:1:1.

[0023] S2. Coating and drying: The mixed liquid slurry is evenly sprayed on the surface of the powder metallurgy parts by spraying, and then the parts are placed in an oven at 80°C for baking and drying for 5 minutes.

[0024] S3. Sintering treatment: The coated and dried powder metallurgy parts are placed in a mesh belt furnace for sintering. The sintering temperature is 1120° C. and the holding time is 30 minutes. After the sintering is completed, the powder metallurgy parts are quenched.

[0025] In one embodiment of the present invention, in said S1, the particle size of the nickel-based alloy powder is -325 mesh to +500 mesh.

[0026] Embodiment 2:

[0027] See also Figure 1 As shown, a process for forming a high alloy densified layer on the surface of a powder metallurgy part comprises the following steps:

[0028] S1. Raw material preparation: The material of the powder metallurgy parts in this case is F0008. The selected alloy powder composition is copper-based pre-alloyed powder, with a composition of 38% manganese, 9% nickel, and the rest is copper. The organic liquid is a special resin liquid and trimethylbenzene solution;

[0029] Use a high-speed disperser to mechanically mix the special resin liquid and trimethylbenzene for 10 minutes, then gradually add the alloy powder while dispersing it with the high-speed disperser. After it is completely added, disperse it for another 20 minutes. Finally, the mixing ratio of the alloy powder, resin liquid and trimethylbenzene solution is 8:1:1.5.

[0030] S2. Coating and drying: Use the dipping method to immerse the powder metallurgy parts into the liquid mixed slurry. After the parts are taken out, use a spin dryer to spin dry the excess slurry on the surface of the parts, and then place the parts in an 80℃ oven for baking and drying for 5 minutes.

[0031] S3. Sintering treatment: The coated and dried powder metallurgy parts are placed in a mesh belt furnace for sintering. The sintering temperature is 1120° C. and the holding time is 30 minutes. After the sintering is completed, the powder metallurgy parts are quenched.

[0032] In one embodiment of the present invention, in S1, the particle size of the copper-based alloy powder is -325 mesh to +500 mesh.

[0033] Application test examples:

[0034] Test material: iron-based powder metallurgy material F0008, gear parts with a tooth top diameter of Φ50 mm were selected, and the parts were surface treated according to S1-S3 in Example 1 and Example 2, respectively, and powder metallurgy parts prepared by traditional powder metallurgy treatment method were used as comparison;

[0035] The powder metallurgy parts were processed according to the steps in Example 1 and Example 2, respectively. At the same time, conventional powder metallurgy processes were used to produce heat-treated parts of the same material. The surface hardness of each sample was tested using a hardness tester, and the tooth strength was tested using a universal testing machine. Each test sample was placed in a salt spray test chamber for corrosion resistance testing, and the data was recorded. The specific data is as follows:

[0036]

[0037] As can be seen from the above, the surface hardness is significantly improved. The surface hardness of the carburized layer in Example 1 and Example 2 reaches HRC48-53 and HRC 45-50 respectively, which is much higher than HRC 27-33 of conventional heat-treated parts.

[0038] The mechanical strength is greatly improved. The tooth strength of the first and second embodiments is 4380N and 3950N respectively, which is much higher than the 2330N of the heat-treated gear.

[0039] The corrosion resistance is enhanced. After 12 hours of salt spray test, there is no corrosion in Example 1 and Example 2, while corrosion occurs in the prior art.

[0040] In summary, the new method for preparing the surface alloying layer of powder metallurgy parts has significant advantages in improving the surface hardness, mechanical strength and corrosion resistance of powder metallurgy parts.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for forming a high alloy densified layer on the surface of a powder metallurgy part, characterized in that: The following steps are involved: S1. Raw material preparation: selecting alloy powder with high mutual solubility with powder metallurgy substrate and fully stirring and mixing with organic resin liquid to obtain mixed slurry; S2, coating and drying: coating the prepared powder slurry on the surface of the powder metallurgy substrate, and then drying it; S3. Sintering treatment: placing the coated and dried powder metallurgy substrate in a sintering furnace for sintering to form a dense alloyed infiltration layer on the surface of the part, thereby obtaining a powder metallurgy part with a high alloy densified infiltration layer on the surface.

2. The process for forming a high alloy densified layer on the surface of a powder metallurgy part according to claim 1, characterized in that: In S1, the melting point of the alloy powder is at least 200° C. lower than that of the powder metallurgy substrate, and the particle size of the alloy powder is -325 mesh.

3. The process for forming a high alloy densified layer on the surface of a powder metallurgy part according to claim 1, characterized in that: In S2, the drying process is carried out by air drying or drying in an oven.

4. The process for forming a high alloy densified layer on the surface of a powder metallurgy part according to claim 1, characterized in that: In the S3, the sintering temperature is set to be 50° C. or higher than the melting point of the alloy powder, and the high temperature period is not less than 5 minutes.

5. The process for forming a high alloy densified layer on the surface of a powder metallurgy part according to claim 1, characterized in that: In S3, the alloy powder coated on the surface is melted, and the molten alloy liquid is sucked into the surface layer of the part by the capillary force of the pores of the powder metallurgy part, and continuously diffuses into the matrix.

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