KR100462702B1 - Method of manufacturing sliding parts - Google Patents

Abstract

The present invention relates to a method of manufacturing a sliding part, comprising: a cemented carbide powder containing a hard particle such as carbide, nitride, boride, and a metal binder powder containing a nickel base element containing an element that lowers the liquidus temperature at a sintering temperature. The sintered body is manufactured by heating, and the sintered body is placed on the base material and secondly heated and joined at the joining temperature to directly heat-bond the iron base material without using any filler material, thereby providing excellent bonding strength between the wear resistant material and the base material. To grant.

Description

Method of manufacturing sliding parts

The present invention relates to a method of manufacturing a sliding part, in particular, a heat-bonded molded body of a cemented carbide composed of hard particles such as carbides, nitrides and borides and a metal-based binder with a base metal made of an iron alloy or sintered a mixed powder of the cemented carbide. The present invention relates to a method of manufacturing a sliding part without using a separate filler material by placing a sintered body on a base metal made of an iron alloy and heating it.

In general, cemented carbide is composed of hard reinforcing particles such as tungsten carbide, chromium carbide, nitride, boride, etc., and a single metal such as nickel and cobalt, or a binder of nickel alloy and cobalt alloy. It is widely used in sliding parts of internal combustion engines that require great tools and wear resistance.

In order to use such cemented carbide as wear-resistant parts such as sliding parts of internal combustion engines, it is common to use a filler metal after joining it to a metal base material, but when joining using such filler metal, the bondability between the cemented carbide and the bonded base material is used. In addition, the mechanical properties of the joining body are limited by the mechanical properties such as strength and impact resistance of the filler metal itself. Therefore, the method of directly joining the wear-resistant material and the iron base material without using the filler metal is mechanical. It is advantageous in terms of characteristics and economics.

The method of directly joining the wear-resistant member and the base material is disclosed in Japanese Patent Laid-Open No. 62-182407 and Japanese Patent Laid-Open No. 62-185806. According to this method, a binder composed of hard particles such as carbide and nickel and nickel alloy The joined body is manufactured by simultaneously sintering and cementing the cemented carbide by molding the powder and sintering the molded body on the bonded base material.

However, according to the conventional method of joining the molded body to the base material at the same time as sintering, the molded body maintains only its shape but its own strength is very low, so there are many difficulties in handling, and it is impossible to apply a load directly to the joined body. There is a problem that is difficult to improve the state of. In addition, since shrinkage occurs during sintering of the molded body, it is difficult to precisely control the dimensions of the final joined body, and there is also a problem that post-processing treatment is required after the sintering process. Therefore, it is advantageous to join the molded body with the base material in the sintered or pre-sintered state in advance than the conventional method of simultaneously joining the molded body to the base material.

Accordingly, the present invention does not use a filler metal, and directly sinters the cemented carbide with a base metal made of an iron alloy, or sinters it onto an iron alloy intended to join a mixed powder of hard particles such as carbides, nitrides and borides and a metal binder. It is an object to provide a method of manufacturing sliding parts by simultaneously bonding.

1 is a view showing a wear-resistant material and the base material constituting the sliding part,

2 is a view showing a bonded body of the wear-resistant material after the bonding step;

3 is a schematic diagram showing a joining interface in a state where joining is completed.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

1 is a view schematically showing a cross section of a sliding part according to the present invention, which is composed of a wear-resistant material 1 and a base material 2, for example, a carbide-based cemented carbide and a joint of steel. The wear resistant material 1 is a sintered body 1b obtained by heating and sintering a mixed powder of hard particles such as carbides, nitrides and borides and a binder of a nickel base to which a liquid phase temperature reducing element is added, and the base material 2 is cast iron, Iron-based alloys such as carbon steel and alloy steel.

The wear-resistant material 1 and the base material 2 are brought into contact with each other with respect to a desired bonding surface and then heated to a predetermined temperature to prepare a bonded body as shown in FIG.

In the wear-resistant material 1 of FIG. 1, the ratio of hard particles, for example, tungsten carbide, is suitably about 60-90%. When the amount of carbide is less than 60%, the hardness required for sliding parts cannot be obtained. When the amount of carbide is more than 90%, sufficient bonding strength cannot be obtained because the amount of binder that contributes to bonding with the base material is small.

As the binder of the wear resistant material, nickel, which is easily alloyed with elements such as silicon, chromium, iron, and boron, which lower the liquidus temperature than cobalt, is preferable. Silicon and boron were selected as elements to lower the liquidus formation temperature of the binder, and the appropriate amounts of two elements were determined as shown in Table 1 within the range of not significantly impairing the mechanical properties such as sintering and toughness of the cemented carbide.

division Ni Si B Junction temperature Example 1 Bal 1wt% 8wt% 1100 ℃ Example 2 Bal 3wt% 8wt% 1100 ℃ Example 3 Bal 6wt% 8wt% 1200 ℃ Example 4 Bal 12wt% 8wt% 1200 ℃ Example 5 Bal 15 wt% 8wt% 1200 ℃ Example 6 Bal 9wt% 1wt% 1300 ℃ Example 7 Bal 9wt% 2wt% 1200 ℃ Example 8 Bal 9wt% 4wt% 1200 ℃ Example 9 Bal 9wt% 8wt% 1200 ℃ Example 10 Bal 9wt% 10wt% 1100 ℃ Example 11 Bal 9wt% 15 wt% 1000 ℃

When the amount of silicon is small, the effect of lowering the liquid-forming temperature is small, and the bonding state is poor. As the amount of silicon increases, the hardness of the binder is increased by solid solution strengthening. However, when the amount of silicon is too high, a compound with nickel is formed. Makes wear resistant. If the amount of boron is too small, as in the case of silicon, the effect of lowering the liquidus formation temperature is insignificant, and the bonding state is poor. If the boron content is too high, alloying occurs between the binder and the base material, which is a carbon steel, to form a weak phase at the bonding interface. Problems with strength Appropriate amount of the liquid phase temperature lowering element is about 3-12wt% silicon and about 2-10wt% boron based on nickel base.

A molded article was prepared from the powder prepared by the above composition, and the bonding experiment was performed at a temperature range of 900-1400 ° C. As shown in Table 2, the bonding did not occur at a temperature of less than 1000 ℃. At temperatures above 1300 ° C, compounds vulnerable to the bonding interface were formed, resulting in low bonding strength and severe deformation of the wear resistant material and the base material. Bonding temperature was stable in the range of 1000-1300 ℃.

Junction temperature time Bonding area ratio of abrasion resistant material and base material 900 ℃ 60 minutes 0% 950 ℃ 60 minutes 14% 1000 ℃ 60 minutes 96% 1050 ℃ 60 minutes 99% 1150 ℃ 60 minutes 100% 1300 ℃ 60 minutes 100% 1400 ℃ 60 minutes 100%

Therefore, in the present invention, a sintered body in which 3-12 wt% of silicon and 2-10 wt% of boron are added as a liquid phase temperature reducing element is bonded to a nickel base, which is a binder, by heating to a temperature of 1000-1300 ° C. and a wear resistant material having a good bonding state. The bonded body of the base material was obtained.

Pre-sintering the molded body of the mixed powder of the composition is performed separately at a temperature of 700-900 ° C. to produce a plastic sintered body having a certain strength, which is brought into contact with the joining surface with the base material and heated to sinter and join simultaneously. It was done. Sintering junction temperature range was 1000-1300 degreeC. Also in this case, the favorable joined body was obtained similarly to the case where the sintered compact was joined.

Example A

In the nickel base, silicon and boron, which are metals for lowering the liquidus temperature, were mixed with a binder containing tungsten carbide and 9.0 wt% and 8.0 wt%, respectively, in a ratio of 25:75. 1.0 wt% of a lubricant (kenolube) was added to the mixed powder. This mixed powder was molded and sintered at 1200 ° C. for 60 minutes to prepare a sintered body. The sintered compact had a hardness of HRA 86 or more.

The thus prepared sintered body was bonded for 60 minutes at a bonding temperature of 1150 DEG C and a bonding base material made of carbon steel (SM45C). It can be seen that in the bonding with the steel, pores due to melting are not formed at the steel side of the bonding surface, and a continuous bonding interface is formed. As a result of measuring the shear strength of the bonded specimens, the shear strength of the bonded body was 400 kg / cm 2 or more.

Example B

The alloy powder used in Example A was press-molded at a molding pressure of 2 Ton / cm 2 to prepare a molded article. The molded body was heated at 850 ° C. for 60 minutes to produce a plastic sintered body having a hardness of HRA 60 or more, which was then combined with a bonded base material made of carbon steel (SM45C) and resintered at 1200 ° C. for 90 minutes. The sintered body had a hardness of HRA 86 or more, and the state of the bonding interface was the same as that of the sintered body. As a result of measuring the shear strength of the bonded specimens, the shear strength of the bonded body was 400 kg / cm 2 or more.

Example C

The alloy powder used in Example A was press-molded at a molding pressure of ² ton / cm ² to prepare a molded article. . The sintered body had a hardness of more than HRA86, and at the joint interface, the unbonded portion was not observed at all. The shear strength of the bonded specimen was 400kg / cm ² or more.

In order to improve the wear resistance of the sliding surface in a component having a sliding surface, a number of methods for forming a bonded body of a wear resistant material and an iron alloy have been proposed. In the present invention, it is possible to directly bond the sintered body or mixed powder of the wear-resistant material to the iron-based base material without using a solvent metal, thereby producing a bonded body having excellent bonding strength and economical efficiency.

Claims (7)

Cemented carbide powder containing 60-90% by weight of one or more hard particles selected from carbides, nitrides and borides, and 10-40% by weight of metallic binder powder containing silicon and boron as elements to lower liquidus temperature on a nickel base A method for producing a sliding part, comprising: heating a primary at 1050-1200 ° C. to produce a sintered body, and placing the sintered body on a base material, followed by secondary heating at 1000 to 1300 ° C. to join. delete The method of claim 2, wherein the silicon is 3-12 wt% in the binder and boron is 2-10 wt% in the binder. The method of claim 1, wherein the primary heating temperature is 1200 ℃. The method of claim 1, wherein the secondary heating temperature is 1050-1150 ℃. With an element to lower the liquid phase temperature of nickel base silicon, boron, the balance of 60 of 10 to 40% by weight of the metal-based bonding material powder made of a nickel, a carbide, a mixture of one or more hard particles selected from the group consisting of nitride, boride hard metal powder Make a molded body to 90% by weight , and the molded body is heated and sintered to the base material at 1000-1200 ℃ , the binder is 3-12% by weight of silicon, 2-10% by weight of boron, the balance is made of nickel A method of manufacturing a sliding part, characterized in that. delete