JPH0649928B2 - Sliding contact member with excellent wear resistance - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a self-lubricating sliding contact member formed by forming an Al diffusion coating layer by an Al pack method on the surface of a metal base material.

(Prior Art) In recent years, in order to prevent abnormal wear, scuffing, corrosion wear, etc. of a cylinder system that occurs in an engine using a turbocharger, a supercharger, EGR that utilizes exhaust gas, etc., along with the increase in output of automobile engines, It has been a major problem to improve the sliding characteristics of the sliding contact member that constitutes the cylinder material, that is, to improve the wear resistance and the self-lubricating property.

Conventionally well-known wear resistance and corrosion resistance treatments include technologies such as gas nitrocarburizing, chromium plating, and wire explosion spraying. In the case of gas nitrocarburizing, cast iron (FCH alloy cast iron) bases are used. As it hardens, the edge of the graphite part becomes a blade, causing galling on the piston and piston ring, etc.
As a result, abrasion scuff occurs, and in the case of chrome plating, it is weak against sulfuric acid corrosion and causes corrosive wear.In addition, in the case of stainless steel wire explosion spray, compatibility with the piston ring is poor and scuff occurs, etc. However, it is difficult to satisfy the above problems.

On the other hand, a surface treatment method for forming an Al diffusion coating layer on the surface of a metal substrate, a so-called Al pack method, has been developed (see, for example, JP-A-56-81668).

However, in the conventional Al pack treatment, a metallic base material containing Ni is embedded in a pack agent (generally consisting of Al powder, alumina powder and halogenated activator) and subjected to high temperature treatment in an inert gas (about 800 ° C. or higher). Then, since the Al diffusion coating layer is formed on the surface of the metal substrate, the Al diffusion coating layer is dominated by high hardness AlNi having a body-centered cubic structure and has a hexagonal structure, It contains only a small amount of Al ₃ Ni ₂ which is rich in lubricity. When a sliding contact member such as a cylinder is formed of a material having an Al diffusion coating layer having such a structure, the sliding contact member itself has very excellent wear resistance and corrosion resistance, but it has a high hardness, so that the mating member is significantly It has a drawback of causing abrasion, and is not suitable as a sliding contact member.

(To be Solved by the Invention Problems) In order to reduce the wear of the mating member, it is conceivable to increase the mixing ratio of Al ₃ Ni ₂ having the self-lubricating properties, mixing of Al ₃ Ni ₂ If the ratio becomes too large, the properties of Al ₃ Ni ₂ which are mechanically brittle and thermally unstable dominate, and crack peeling easily occurs. Therefore, it is necessary to optimally control the mixing ratio of Al ₃ Ni ₂ and AlNi in the Al diffusion coating layer.

The inventors have found that Al ₃ Ni ₂ in the Al diffusion coating layer
It was found that the mixing ratio of AlNi and AlNi greatly depends on the processing temperature in the Al pack processing. Then, it was found that Al ₃ Ni ₂ and AlNi can be mixed appropriately by appropriately selecting the pack processing temperature.

(Object of the Invention) The present invention has been made based on the above findings, and appropriately selects the mixing ratio of two compounds of Al ₃ Ni ₂ and AlNi which are deposited on the surface of a metal base material by the Al pack treatment, and also the ceramic particles. The object of the present invention is to obtain a sliding contact member having excellent wear resistance by appropriately dispersing

(Means for Achieving the Purpose) In the present invention, as means for achieving the above object, N
i on the sliding contact surface of the metal base material containing the ceramic particles,
Obtained by performing an Al pack treatment under a low temperature condition of less than 00 ° C., where Al ₃ Ni ₂ and AlNi are mixed and
Al containing 15% by weight of ceramic particles dispersed therein
A diffusion coating layer is formed. Here, as the ceramic particles, SiC, SiO ₂ or the like is used.

(Operation) In the present invention, the following operations are obtained by the above means.

That is, the Al diffusion coating layer obtained by the Al pack treatment under the low temperature condition has a high self-lubricating property.
Since Al ₃ Ni ₂ and high-hardness AlNi are present in a suitable mixing ratio and the ceramic particles that are high-hardness particles are dispersed, the scuff resistance and wear resistance of the sliding contact member are significantly improved.

Further, the adhesive bond between the Al diffusion coating layer and the ceramic particles is improved, and the ceramic particles are prevented from falling off due to friction.

If the dispersion amount of the ceramic particles is less than 5% by weight, the effect of improving the friction resistance of the sliding contact member does not appear, and if it is 15% by weight or more, it becomes too hard and wear of the mating member increases.

(Example 1) 10% by weight of Si on the surface of a metal base material made of flake graphite cast iron
Plating is performed using a Ni plating bath in which C is dispersed, and the metal base material on which the Ni-SiC plating layer thus obtained is formed is subjected to Al pack treatment under the following conditions,
Al with 10% by weight of SiC dispersed on the surface of the metal substrate
A diffusion coating layer was formed.

Composition of pack agent Al ₂ O ₃ powder (# 100 to 200): 67.5 (wt%) Al powder (# 100 to 200): 30.0 (wt%) Misch metal powder (# 80 to 200): 0.5 (wt%) NH ₄ Cl powder: 2.0 (wt%) The metal base material is embedded in each of the above-mentioned packing materials, and the metal base material is embedded in an inert gas (eg, H ₂ , N ₂ , Ar, etc.) atmosphere.
It heat-processed at 600 for 0.1 hour. The pack processing temperature is
550 to 680 ℃ is desirable, and pack processing temperature is 550 ℃
If the temperature is less than the above, Al diffusion into the Ni-SiC plating layer is not sufficiently performed, a desired Al diffusion coating layer cannot be obtained, and if the pack processing temperature reaches a high temperature of 700 ° C or higher, as shown in FIG. This is not desirable because the SiC plating layer may peel off from the base material. FIG. 1 shows the change in the peeled area ratio of the Ni—SiC plated layer on the cast iron base material with respect to the pack processing temperature.

However, the thickness of the Al diffusion coating layer depends on the pack processing time, and it is necessary to determine the pack processing time as desired.

Next, a sliding contact member (for example, a cylinder) and a mating member (for example, a piston ring) obtained by performing an Al pack process while changing the SiC content in the Ni-SiC plated layer
When subjected to a dry abrasion test, the results shown in FIG. 2 were obtained. Here, the solid line A shows the amount of wear of the sliding contact member, and the dotted line B shows the amount of wear of the mating member.

The reciprocating sliding tester shown in FIG. 3 was used as the test device. That is, the mating member (piston ring piece) 13 is reciprocated while being pressed with a predetermined surface pressure P on the upper surface of the sliding contact member (cylinder piece) 12 fixed on the base 11.
Both wear weights were measured. Here, reference numeral 14 is a motor, 15 is a crank that converts the rotational movement of the motor 14 into reciprocating movement, 16 is a holder that supports the mating member 13, 1
Reference numeral 7 is a linking member that connects the holder 16 and the crank, and 18 is a support base.

The test conditions were as follows.

Surface pressure P: 10 Kg / mm ² , speed: 700 cycles / min, distance N: 2
0000, friction length: 10 mm, friction method: reciprocating friction in the atmosphere, wear measurement: gravimetric method As is clear from the results of the above test, the Al diffusion coating layer containing 5 to 15 wt% of SiC dispersed therein is extremely excellent. It can be seen that it has abrasion resistance and scuff resistance. If the SiC content is less than 5% by weight, no improvement in the wear resistance effect appears, and if the SiC content exceeds 15% by weight, it becomes too hard and damages the mating member, so that the wear amount of the mating member increases. The thickness of the Al diffusion coating layer is 5 to 30.
It suffices if it is in the range of μ, but from a practical point of view 10 to 20 μ
Is more preferable.

In the above-mentioned embodiment, the Al-pack treatment is applied to the Ni-plated layer in which SiC is dispersedly contained. However, the Al-P plated layer in which SiC is dispersedly contained, or Ni
Alloy cast iron surface containing s
The sliding contact member of the present invention can be obtained even by performing the l-pack treatment.

Of course, other suitable ceramic particles may be used instead of SiC.

(Effects of the Invention) As described above, according to the present invention, it is obtained by subjecting the sliding contact surface of the metal base material containing Ni and ceramic particles to the Al pack treatment under the low temperature temperature condition of less than 700 ° C. ,
Since an Al diffusion coating layer in which Al ₃ Ni ₂ and AlNi are mixed and 5 to 15% by weight of ceramic particles are dispersedly contained is formed, it is rich in self-lubricating Al ₃ Ni ₂ and ductility. By mixing with AlNi, the sliding characteristics are remarkably improved, the adhesion to the metal base material and the durability are also remarkably improved, and the abrasion resistance is remarkably improved by the presence of the ceramic particles.

Further, since the adhesive bond between the Al diffusion coating layer and the ceramic particles is strengthened, the ceramic particles are prevented from falling off even during high-speed friction, and the scuff resistance is also improved. Therefore, it is possible to obtain the optimum sliding contact member as a material for cylinders for automobile engines.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing the change in the peeled area ratio of the Ni—SiC plating layer on the cast iron base material with respect to the pack treatment temperature, and FIG. 2 is a sliding contact member and its counterpart with respect to the SiC dispersed content in the Ni plating layer. FIG. 3 is a side view showing the outline of the wear test device, which is a characteristic diagram showing a change in the amount of wear with a member.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuuo Tabata 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-56-81668 (JP, A) JP-A-56- 87661 (JP, A)

Claims (1)

[Claims] 1. A metal base material containing Ni and ceramic particles, which is obtained by subjecting a sliding contact surface of the metal base material to an Al pack treatment under a low temperature condition of less than 700 ° C., in which Al ₃ Ni ₂ and AlNi are mixed. A sliding contact member having excellent wear resistance, characterized in that an Al diffusion coating layer containing 5 to 15% by weight of ceramic particles dispersed therein is formed.