JPS5854189B2 - thermal spray powder material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal spray powder material used for sliding parts of cylinders, pistons, high-speed rotation bearing metals, etc.

Hitherto, high 5i-Ad alloys have been used for a variety of purposes as wear-resistant and heat-resistant cast members, such as pistons and cylinder blocks found in some American cars.

If the Si percentage in this high 5i-A1 alloy increases, the workability will deteriorate and the melting point will also increase, which will have an adverse effect on workability, so the Si percentage is limited to 15 to 20 parts.

The wear resistance of the high 5i-A1 alloy does not depend on the AA base, but rather on the hardness of the Si.
i%, the size of Si particles, the shape of Si, etc. have a large effect on the wear resistance of the parts in which it is used.

In the case of high 5i-A# alloys, machining may generate two cracks within the brittle Si grains, which may cause Si to fall off during operation, causing scuffing on itself or on the sliding surface of the other party. .

Therefore, sufficient care must be taken not only during finishing but also during rough machining.

The size and shape of the shredded Si are also kept within a certain range.

There is a method of using high 5i-A1 alloy as a thermal spray powder material, and it has been confirmed that it has wear resistance comparable to high 5i-A6 alloy cast material, but it has not achieved properties superior to high 5i-A6 alloy. is the current situation.

Thermal spray powder materials other than high 5i-A1 alloys, such as W C-
By using Co-based, Mo-based materials, etc., high 5i
Although it can be expected to have wear resistance that is several orders of magnitude better than -A1 alloy casting material, it is difficult to apply to mass production due to the high powder cost and difficult grinding process.

In addition, a thermal sprayed material made of steel thread can be considered as a thermal sprayed material with wear resistance between that of high 5i-AA alloy and WC-Co, but when coated on an AI base material, peeling may occur due to the difference in thermal expansion. Some excellent properties cannot be expected due to a decrease in interlayer strength due to oxidation during thermal spraying, the presence of pores, etc.

In addition, plating also exhibits excellent properties as a wear-resistant coating for sliding surfaces, but it is not a desirable approach because the process is complicated and there are pollution problems such as waste liquid.

As mentioned above, in the case of a high 5i-A1 alloy, the amount, size, and shape of triSi greatly affect the wear resistance.

It is preferable that rounded Si particles are uniformly dispersed in the AI base.

Therefore, if the amount, size, and shape of this Si can be controlled within a certain range, a sliding surface with excellent wear resistance can be obtained.

The presence of pores in the shriveled thermal sprayed layer causes a decrease in interlayer strength, and when used as a sliding surface, particles may pass through or fall off.

Therefore, it is desirable that the thermal spray coating be non-porous.

Based on the above knowledge, the present inventors have made diligent efforts to compensate for the shortcomings of the prior art.

The purpose of this invention is to create a thermal spray powder material that is non-porous, has excellent wear resistance, is low cost, and is suitable for mass production, and provides it here.

The present invention is a thermal spray powder material characterized in that a high carbon ferrochrome alloy is mixed in a volume ratio of 5 to 50% with a high 5iA1 alloy containing 16 to 40% Si.

The use of high 5i-A# alloy in the present invention is due to the high S
The sprayed layer of i-A 1 alloy is non-porous, has a lower melting point than other sprayed materials, has a large supply amount per unit time and is suitable for high-volume production, has good adhesion to the base material, and has good thermal expansion because it is a similar metal. The difference is relatively small.

S of high 5i-AA alloy casting material whose thermal spray layer can be cut
This is because it has the advantage of being able to contain more Si than i1, and in order to add to this advantage even better wear resistance, it is possible to arbitrarily control the amount, size, and shape of Si. It was discovered that a ferrochrome alloy can be mixed therein.

The reason why the Si content is set at 16 to 40% is that if it is less than 16%, the spraying workability will be good, but the thickness of the sprayed film will be thin; on the other hand, if it exceeds 40%, the sprayed film will become brittle. , since the thermal spraying efficiency will also deteriorate, the amount of Si in the Al-Si alloy should be 16~
It was 40 rice cakes.

=! The mixing ratio of high carbon ferrochrome alloy was 5 by volume.
The reason why we set it as ~50 rice cakes is because if it is less than 5 parts, the effect of adding it is 1.
If it exceeds 50, pores will appear in the sprayed coating.

Examples are shown below.

Example 1 As thermal spray powder material (A) Fe-63%Cr-82%C-0.8%S
i high carbon ferrochrome powder with size less than 350 mesh, (BI Al-23%5i-41%Cu-10FeO
, 5Mg high 5i-A1 alloy powder with a size of 250 mesh or more and 200 mesh or less.

(0 above (4)t (B) Two types of alloy powder, (A)
: (B) = 2:3 mixture was prepared, and each was coated with a thickness of 280 to 300μ by plasma spraying on an aluminum plate that had been previously degreased, washed, dried, and shot blasted. , the surface and cross section were observed.

The surface hardness of the sprayed layer using (4) is 600 to 850 micro Vickers (mHv 100 g), but the porosity is very high, about 15 to 20%, as shown in FIG.

There are almost no pores in the products made using shredded (B),
The surface hardness is 139 to 215, which is comparable to that of a high 5iA1 alloy cast material, but the Si grains are very small at 1/200 as compared to the cast material, as shown in Figure 2.

(Despite the fact that the surface of the sprayed layer using A7 contains as much as 40 (cJt%) of high carbon ferrochrome alloy, as shown in Figure 3, there are almost no pores visible in the high 5i-A7 alloy. The presence of hard particles of carbon ferrochrome alloy can be seen.

Also, the average hardness is 100~1 compared to high S1-A6 alloy.
It went up by 50.

In addition to medium high carbon ferrochrome alloy, high 5i-A1 alloy 7
Mixed powder of 0" and TiC30"tφ, and high 5i
Similar experiments were conducted on mixed powders of -A1 alloy 80 (l'Jt) and alumina 20°, and the sprayed coating layers were observed. It was observed that aluminum was uniformly scattered throughout the high 5i-A1 alloy with almost no pores.

Example 2 The mixing ratio of high 5i-A1 alloy and high carbon ferrochrome alloy is 95%:5%, 80%:20%, 60%:
A mixed powder of 40 mm and 50 mm was prepared, and as in Example 1, a 300 μm coating was applied by plasma spraying, and the surface was observed.

The ratios of 95:5, 80:20 and 60:40 gave good films with almost no pores, whereas the ratio of 50:50 had slightly more pores.

The hardness is mHv 100 g and 80:20 is 1
53-274.50:50 was 209-421.

Example 3 A wear test was conducted on test pieces coated with various thermal spray powders, and the results shown in Table 1 were obtained.

The test piece shape is a ring of 50φmrtt x 10myyt,
The flock has 8 angles, and the test conditions were: constant oil addition, ring rotation speed: 4000 rpm, 1 load: 3
I went for 1 hour with 5 kg.

The high carbon steel shown in Table 1 has a powder size of 10 to 50 microns.

The test piece was processed by cutting and grinding, and the surface roughness was 0.3 to 0.
．． It was 6μRz.

In general, wear-resistant materials have a high melting point and tend to have more pores than other thermal sprayed materials, which reduces the interlaminar strength of the thermally sprayed layer and prevents particles from passing through and falling off when used as a sliding surface. This may occur.

The high SiA [alloy has a relatively low melting point as a wear-resistant material, and as seen in Figure 2, it has almost no pores when compared to the high carbon ferrochrome alloy shown in Figure 1.
As shown in Table 1, the wear resistance also shows excellent results.

In order to further improve the excellent wear resistance and non-porosity of the thermal sprayed layer of the high Si-A1 alloy, the present invention applies a high carbon ferrochrome alloy to the high 5i-A1 alloy with pores, as seen in the examples. It is a mixture in a range where there is no such thing.

Looking at its properties in Table 1, it can be seen that when combined with a high 5i-A1 alloy block, the high Si-A1 alloy ring did not show good results, whereas the high 5i-A1 alloy and high carbon steel mixed ring did not show good results when combined with a high 5i-A1 alloy block. The sprayed powder showed good results due to the action of high carbon steel.

Among the Cr-plated blocks, those coated with high carbon steel thermally sprayed seize, whereas those coated with a mixed powder of high 5i-A# alloy and high carbon steel were seized due to the action of high 5i-A1 alloy. Showing good results.

It has been found that depending on the material used, better interaction results can be obtained than with high 5i-A# alloy alone or high carbon steel alone.

As mentioned above, by adding a high melting point and wear resistant material to the high 5i-A1 alloy powder, its properties not only have the best of both worlds, but in some cases even better properties due to their interaction. It was found that

In other words, it is thought that if a solid lubricant is applied to the thermal sprayed layer, the initial fit will be even better.

[Brief explanation of drawings]

FIG. 1 is a surface micrograph of a thermally sprayed layer when high carbon ferrochrome alloy powder is thermally sprayed, and the black parts are pores.

Claims (1)

[Claims] Containing 116-40% silicon, 1 piece high silicon aluminum alloy, 5-50% high carbon ferrochrome alloy by volume.
A thermal spray powder material characterized by being mixed with