JPH0649931B2 - Sliding member with self-lubricating property - 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 base material, 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, Al with high lubricity
_It contains only a small amount of ₃ Ni ₂ . When forming a sliding contact member such as a cylinder with a material having an Al diffusion coating layer having such a structure, while the sliding contact member itself has extremely excellent properties in wear resistance and corrosion resistance, it has a high hardness, so 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 present inventors have confirmed that Al ₃ Ni ₂ in the Al diffusion coating layer
Paying attention to the fact that the mixing ratio with AlNi greatly depends on the processing temperature during Al pack processing, various sliding temperature of the Al diffusion coating layer (that is, wear amount and friction coefficient) was obtained by varying the pack processing temperature. ) And the amount of wear of the mating member (here, flake graphite cast iron is used), and the results shown in FIGS. 3 and 4 were obtained. 3 and 4
The figure shows changes in the wear amount and friction coefficient between the sliding contact member and the mating member with respect to the Al ₃ Ni ₂ / AlNi ratio. Here, the Al ₃ Ni ₂ / AlNi ratio is represented by the X-ray intensity ratio by X-ray analysis for the Al diffusion coating layer. These third
As is clear from the figures and FIG. 4, the Al ₃ Ni ₂ / AlNi ratio in the Al diffusion coating layer is 0.4 to 4 (in other words, Al ₃
It was found that both the Al diffusion coating layer and the mating member exhibit excellent sliding characteristics when the production rate of Ni ₂ is 30 to 80%).

(Object of the Invention) The present invention has been made based on the above findings, and it is possible to deposit _{2 of} Al ₃ Ni ₂ and AlNi deposited on the surface of a metal substrate by an Al pack treatment.
The object is to obtain a sliding contact member having excellent sliding characteristics by appropriately selecting the mixing ratio of the compounds.

(Means for Achieving the Purpose) In the present invention, as a means for achieving the above-mentioned object, the sliding contact surface of the metal base material formed by forming a plating layer mainly containing Ni on the surface of the metal base material, Using an Al packing agent containing misch metal, it was obtained by performing an Al packing treatment under a low temperature condition of less than 700 ° C., and the X-ray intensity ratio was 30 to 8
An Al diffusion coating layer containing 0% Al ₃ Ni ₂ and the balance AlNi and misch metal is provided.

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

That is, it was obtained by Al pack treatment under low temperature conditions
Al ₃ N with high self-lubricating property in Al diffusion coating layer
Since i ₂ and AlNi having high hardness are present in a suitable mixing ratio, the sliding characteristics of the sliding contact member are significantly improved.

Further, the Al diffusion coating layer has a low friction coefficient, and when it is used as a cylinder for an automobile engine or the like, sliding resistance is reduced.

(Example 1) A metal base material made of flake graphite cast iron obtained by plating the surface of a metal base material with Ni was subjected to Al pack treatment under the following conditions,
An Al diffusion coating layer was formed on the surface of the metal substrate as shown in FIG.

In addition, FIG. 1 shows the cross-sectional structure, which is observed by an electron microscope.
In the figure, A shows the base material, B shows the Ni plating layer, and C shows the Al diffusion coating layer.
Further, the rectangular marks in the figure are marks of the hardness test.

Packing agent composition Al ₂ O ₃ powder (# 100-200): 54.5-62.5 (wt%) Al powder (# 100-200): 30.0 (wt%) Misch metal powder (# 80-200): 0.5 (wt%) %) NH ₄ Cl powder: 7 to 15 (wt%) The metal base material is embedded in the above-mentioned pack agent, and the metal base material is 600 in an inert gas (eg, H ₂ , N ₂ , Ar, etc.) atmosphere.
It heat-processed at 2.0 degreeC for 2.0 hours. Al obtained by the above treatment
When X-ray analysis was performed on the diffusion coating layer, the X-ray intensity diagram shown in FIG. 5 was obtained. When this is analyzed by a known method, this Al diffusion coating layer has an Al content of 38%.
_It can be seen that it is composed of ₃ Ni ₂ and 62% of AlNi. By changing the pack treatment temperature, different Al ₃ Ni ₂ / AlNi ratios can be obtained. That is, the heat treatment temperature is 500 to 750.
Sliding contact member (cylinder) and mating member (piston ring) obtained at each processing temperature by various changes within the range of ℃
When subjected to a dry wear test, a sliding contact member having different sliding characteristics depending on the treatment temperature was obtained as shown in FIG. It should be noted that when the Al pack processing temperature becomes 550 ° C or lower, Ni
Since Al diffusion into the plating layer is not sufficiently performed and the desired Al diffusion coating layer cannot be obtained, as shown in FIG. 7, the wear resistance is poor and the Al pack treatment temperature is low.
At a high temperature of 700 ° C. or higher, this example shows excellent wear resistance, but this is not desirable because the Ni plating layer may peel off from the base material as shown in FIG. This is considered to be due to the difference in the coefficient of thermal expansion between the base material and the plating layer. FIG. 9 shows the change of the peeled area ratio of the Ni plating layer on the cast iron base material with respect to the pack treatment 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.

(Example 2) A metal base material made of flake graphite cast iron obtained by plating the surface of a metal base material with Ni-P was subjected to Al pack treatment under the following conditions, and as shown in FIG. An Al diffusion coating layer was formed on the surface of the.

Fig. 2 (a) shows the cross-sectional structure, which is 100
In the figure, A'indicates a base material, B'indicates a Ni plating layer, and C'indicates an Al diffusion coating layer. Further, FIG. 2 (b) shows the surface portion further magnified 400 times. The rectangular marks in the figure are indentations of the hardness test.

Packing agent composition Al ₂ O ₃ powder (# 100-200): 54.5-62.5 (wt%) Al powder (# 100-200): 30.0 (wt%) Misch metal powder (# 80-200): 0.5 (wt%) %) NH ₄ Cl powder: 7 to 15 (wt%) The metal base material is embedded in the above-mentioned pack agent, and the metal base material is 600 in an inert gas (eg, H ₂ , N ₂ , Ar, etc.) atmosphere.
It heat-processed at 1.0 degreeC for 1.0 hour. Al obtained by the above treatment
When the X-ray analysis was performed on the diffusion coating layer, the X-ray intensity diagram shown in FIG. 6 was obtained. When this is analyzed using a known method, this Al diffusion coating layer is 80%.
It can be seen that it consists of Al ₃ Ni ₂ and 20% of AlNi.
By changing the pack treatment temperature, different Al ₃ Ni ₂ / AlNi ratios can be obtained. That is, the heat treatment temperature is 500 to 7
When the sliding contact member (cylinder) and the mating member (piston ring) obtained at each processing temperature were subjected to a dry wear test while changing variously within the range of 50 ° C, they slide according to the processing temperature as shown in Fig. 8. Sliding members having different characteristics were obtained. It should be noted that when the temperature of the Al pack treatment becomes 500 ° C or lower, N
Since Al diffusion into the i-plated layer is not sufficiently performed and a desired Al diffusion coating layer cannot be obtained, wear resistance is deteriorated as shown in FIG. 8, and the Al pack treatment temperature is 700 ° C or more. At a high temperature, this example shows excellent wear resistance, but it is not desirable because the Ni plating layer may peel off from the base material as shown in FIG.

The result of the wear test of the sliding contact member (for example, cylinder) and the mating member (for example, piston ring) obtained as in the above Examples 1 and 2 was the tenth as compared with that by the conventional surface treatment method. Shown in Figures and 11.

FIG. 10 shows the result of the dry abrasion test,
The reciprocating sliding tester shown in FIG. 12 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: 0.4 kg / mm ² , speed: 700 cycles / min, distance N:
20000, Friction length: 10 mm, Friction method: Reciprocating friction in the atmosphere,
Abrasion measurement: gravimetric method FIG. 11 shows the result of a corrosive abrasion test. As the test device, the same reciprocal sliding tester (shown in FIG. 12) used in the dry abrasion test was used.

The test conditions were as follows.

Surface pressure P: 11.6Kg / mm ² , speed: 700 cycles / min, distance N: 40000, friction length: 10mm, test temperature: normal temperature, corrosive lubricating oil used: 84% diesel engine oil, 10% light oil, Mixture of water 1% and H ₂ SO ₄ 5%, lubrication method: N
= Once every 40,000 times, lubrication, wear measurement: gravimetric method As is clear from the results of both tests, the Al diffusion coating layer according to the example of the present invention has extremely excellent resistance to any conventional surface treatment layer. It can be seen that it has wear resistance and corrosion wear resistance.

The layer thickness range of the Al diffusion coating layer is 5
It is ~ 50μ, and from a practical point of view, it should be 10-20μ. In addition, in the Al diffusion coating layer, 30% of Al ₃ Ni ₂
%, The self-lubricating effect is not exerted, and the wear of the mating member may be accelerated. Also, AlNi
If it is not mixed in an amount of 20% or more, the ductility becomes insufficient, and it becomes impossible to secure the adhesion and durability of the coating layer.

In each of the above embodiments, the metal base material is plated with Ni or
Although the Ni-P plated product has been described, if the metal base material itself contains Ni, the same Al as in each of the above-described examples is used.
Of course, a diffusion coating layer can be formed.

(Effects of the Invention) As described above, according to the present invention, on the sliding contact surface of the metal base material formed by forming the plating layer mainly containing Ni on the surface of the metal base material,
Using an Al packing agent containing misch metal, it is obtained by performing an Al packing treatment under a low temperature condition of less than 700 ° C., and contains 30 to 80% of Al ₃ Ni ₂ in the X-ray intensity ratio, and the rest is AlNi and misch. Since an Al diffusion coating layer made of metal is provided, the sliding property is significantly improved by the appropriate mixture of Al ₃ Ni ₂ which is rich in self-lubricating property, and the presence of AlNi which is rich in ductility makes it possible to form a metal base material. The adhesion and durability of are also significantly improved. Therefore, it is possible to obtain the optimum sliding contact member as a material for cylinders for automobile engines.

[Brief description of drawings]

1 and 2 (a) and (b) are views showing a cross section of the metal structure of the sliding contact member having self-lubricating properties according to the first and second embodiments of the present invention, and FIG. A characteristic diagram showing changes in the wear amount of the sliding contact member (solid line A) and the mating member (solid line B) with respect to the Al ₃ Ni ₂ / AlNi ratio in the Al diffusion coating layer,
Figure 4 shows Al ₃ Ni ₂ / AlNi in Al diffusion coating layer.
FIGS. 5 and 6 are characteristic diagrams showing changes in the friction coefficient of the sliding contact member with respect to the ratio, and FIGS.
The X-ray intensity chart of the Al diffusion coating layer of the sliding contact member according to X-ray analysis by X-ray analysis, and Figs. 7 and 8 show sliding contact obtained by variously changing the pack treatment temperature for Ni plating and Ni-P plating. The figure which shows the result of the abrasion test of the member and the other party member, Figure 9 is the characteristic figure which shows the change of the exfoliation area ratio of the Ni plating layer on the cast iron base material to the pack processing temperature,
10 and 11 are diagrams showing the results of the dry wear test and the corrosion wear test of the sliding contact member according to the embodiment of the present invention, and FIG. 12 is a side view showing the outline of the wear test apparatus.

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

Claims (1)

[Claims] 1. A low temperature condition of less than 700.degree. C. using an Al packing agent containing misch metal on a sliding surface of a metal base material formed by forming a plating layer mainly containing Ni on the surface of a metal base material. obtained by subjecting the Al packing in, self-lubricating, characterized in that and the remaining comprises 30% to 80% of Al ₃ Ni ₂ in the X-ray intensity ratio is provided an Al diffusion coating layer made of AlNi and mischmetal A sliding contact member having.