JPS6332130Y2 - - Google Patents

Description

[Detailed explanation of the idea]

In order to improve the wear resistance of the sliding contact area of a cylinder liner in an internal combustion engine, for example, when molybdenum, molybdenum alloy, or other hard metal is sprayed on the sliding contact surface of the cylinder liner, it will cause a close contact. This invention relates to aluminum alloy sliding parts for internal combustion engines with increased strength. In order to reduce the weight of the engine, the cylinder block and cylinder liner are made of aluminum alloy containing high silicone, but this has problems with wear resistance, so we have to ensure excellent wear resistance. According to Japanese Patent Application Laid-Open No. 52-113415, the sliding surface of an aluminum alloy base material containing a high silicon content is pretreated with plating that does not corrode the silicon, and then the aluminum surrounding the silicon is coated. At the same time, the base is eroded and removed, and the silicon crystals are retained and preserved. Next, the eroded aluminum base is filled with lead by electrodeposition or thermal spraying, so that the lead surface matches the silicon surface. In other words, a method has been proposed in which silicon crystal particles, which are more stable in terms of wear resistance than aluminum base, are evenly distributed on the sliding surface to improve wear resistance. However, the level of wear resistance obtained by the above proposal is not satisfactory for parts such as cylinder liners that are exposed to severe usage conditions. Therefore, it is known to spray molybdenum 11, a molybdenum alloy, or other hard metal onto the sliding portion of an aluminum alloy base material 10 containing high silicon 12, as shown in FIG. 3, for example. The above molybdenum 11 or molybdenum alloy,
In order to thermally spray other hard metals, sliding contact surfaces such as cylinder liners are degreased, rust removed and cleaned to increase the adhesion of the thermally sprayed metal to the aluminum alloy base material 10. ,
Due to insufficient adhesion strength, there is a drawback that the sprayed metal such as molybdenum falls off from the surface of the aluminum alloy base material. On the other hand, a method that increases the adhesion of thermal sprayed metal to prevent it from falling off from the surface of the base material has already been reported in Utility Model Publication No. 7922/1973, which has been developed to increase the adhesion of the sprayed metal to prevent it from falling off from the surface of the base metal. A sliding component for an internal combustion engine is known in which a surface layer is formed by selectively removing the material and then thermally spraying a hard metal onto the surface. However, the above materials are iron-based base materials containing graphite, and cannot be applied to sliding parts such as cylinder liners whose base materials are aluminum alloys containing high silicon content. It's something that doesn't exist. The inventors came to the conclusion that silicon crystal particles in the aluminum alloy base material containing high silicon content were the cause of reducing the adhesion of hard metals such as molybdenum, and discovered the essence of the reduction in adhesion. was investigated. In other words, when molybdenum, a molybdenum alloy, or other hard metal is sprayed onto an aluminum alloy base material containing high silicon content, the portion where silicon is present becomes porous, making it difficult for the sprayed metal to adhere to the base material and causing the sprayed layer to deteriorate. This creates a problem of shedding. This idea was developed in view of the above problems, and provides aluminum sliding parts for internal combustion engines in which the adhesion strength of a sprayed layer made of hard metal to an aluminum alloy base material containing high silicon content is increased. The purpose is to The feature of this invention is that, as shown in FIG. 1, silicon 3 is removed from the surface of an aluminum alloy base material 1 containing a high silicon 3 content.
The point is that the adhesion strength between the hard metal 2 and the base material 1 is increased. When a hard metal is thermally sprayed onto an aluminum alloy base material 1 containing high silicon 3, it is the silicon 1 itself present on the surface that reduces the adhesion strength, and surface treatments such as degreasing and rust removal are necessary. If it is incomplete, the adhesion strength will be reduced, but the silicon 3 that is essentially present in the aluminum alloy base material 1 can be used as a thermal spray coating layer, that is, a hard metal 2.
The adhesion is weak. This invention removes the silicon 3, which has these essential drawbacks, from the surface of the base material 1 to improve the bonding strength with the sprayed metal (hard metal 2), and
By removing the silicon 3, irregular recesses are formed on its surface, increasing the surface area, increasing the contact area with the sprayed metal, and increasing the adhesion. Not only that, the sprayed metal enters the recess P,
Since the mechanical bond is also strengthened, a thermally sprayed coating of the hard metal 2 is formed which has extremely strong adhesion strength compared to conventional thermally sprayed coatings. Silicon 3 on the surface of aluminum alloy base material 1
For example, the silicon 3 can be easily selectively removed by anodizing or shot peening with a molten salt mainly containing sodium chloride or ammonium chloride, and by ultrasonic cleaning with the fine cleaner 210. . The hard metal 2 is formed by wire bombardment spraying,
The material is alternately sprayed with molybdenum and 0.8% carbon steel, with a layer thickness of 120μ. Figure 2 shows the test results of the adhesion strength and tensile strength of the sprayed layer corresponding to the amount of silicon on the surface of the aluminum alloy base material 1 containing high silicon content. The adhesion strength and tensile strength increase significantly when the content of 3 is low. Further, Table 1 shows a comparison of the adhesion strength of the aluminum alloy base material 1 before and after silicon removal, and the silicon removal method in that case. Table 2 is
The processing contents corresponding to the symbols indicating the types of silicon removal methods shown in Table 1 above are shown.

【table】

【table】

[Table] As is clear from Table 1 above, adhesion strength is significantly improved by reducing the amount of silicon. As described above, the present invention not only increases the contact area between the base material and the sprayed hard metal, but also improves the bonding force between the base material and the sprayed hard metal, and the shape of each recess allows the sprayed hard metal to be removed from the sprayed hard metal. Since the sprayed layer can be mechanically firmly held against the base material, the adhesion strength of the sprayed layer to the base material can be significantly improved.

[Brief explanation of drawings]

Figure 1 is a conceptual explanatory diagram of the sprayed coating according to this invention, Figure 2 is a diagram showing the test results of the adhesion strength and tensile strength of the sprayed layer corresponding to the amount of silicon on the surface of the base material, and Figure 3 is It is a conceptual explanatory diagram of a conventional thermal spray coating. 1... Aluminum alloy base material, 2... Hard metal, 3... Silicon.

Claims (1)

[Claims for Utility Model Registration] In an aluminum alloy sliding part for an internal combustion engine in which the base material is made of an aluminum alloy containing high silicon, the surface of the base material includes selected silicon particles on the surface of the base material. A sprayed layer is provided in which a large number of removed and dispersed recesses are provided, each of the recesses is filled with a thermally sprayed hard metal, and the surface of the base material is coated with the thermally sprayed hard metal. Aluminum alloy sliding parts for internal combustion engines featuring: