JPH02129338A - Wear-resistant aluminum alloy - Google Patents

Abstract

PURPOSE:To improve the wear resistance of the title alloy by increasing the amt. of Si in an Al alloy having specific compsn. to which specific amounts of ceramic grains are composed to a specific range. CONSTITUTION:The Al alloy is formed by incorporating, by weight, 5 to 20% ceramic grains into an Al alloy constituted of 20 to 40% Si, 1 to 4% Cu, 1 to 2% Mg, 5 to 10% Fe and/or Ni and the balance Al. In the alloy, Si reduces the thermal expansion and the wear resistance is improved by supplementarily precipitated fine primary crystal and eutectic Si grains. The reduction of the thermal expansion coefficient is however insufficient when the amt. is <20% and the toughness is deteriorated and the mechanical characteristics are deterio rated conversively in the case of >40%. In the ceramic grains, sufficient wear resistance can not be obtd. in the case of <5% composing rate, and the ceramic grains are flocculated and uniform dispersed structure is hard to obtain to deteriorate the mechanical characteristics in the case of >20%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wear-resistant aluminum alloy suitable for sliding members such as partition plates and rolling pistons of rotary compressors for refrigeration and air conditioning.

[Conventional technology]

Approximately 20% silicon as a conventional wear-resistant aluminum alloy
High silicon casting alloys are commonly used, with wear resistance achieved by dispersing hard primary and eutectic Si particles in an aluminum alloy matrix.

[Problem that the invention seeks to solve]

Such conventional wear-resistant aluminum alloys have the following drawbacks.

(1) Wear resistance and seizure resistance are insufficient under severe sliding conditions such as speed and load and lubrication conditions.

(2) The thermal expansion coefficient of aluminum alloy is approximately 20 x 10
-'/''C, about 12 x 10-'/' of iron-based materials
It is larger than C, which poses a problem when the two are used in combination as a mechanical component.

(3) When manufacturing high-silicon aluminum alloys with a silicon content of 20 wt% or more, primary crystal and eutectic S
It is not practical because the grains become coarse and the mechanical properties deteriorate. In addition, it is difficult to compose ceramic hard particles.

The present invention was made in view of the above-mentioned disadvantages of conventional alloys, and provides a wear-resistant aluminum alloy that has sufficient wear resistance and seizure resistance, has a coefficient of thermal expansion smaller than iron-based pots, and is easy to manufacture. It is an object.

[Means to solve the problem]

Therefore, in the present invention, Si 20-40%, Cu1-4
%, 1 to 2% Mg, 5 to 10% of at least one of Fe and Ni, and the remainder substantially At, containing 5 to 20% of ceramic particles. It was made into an alloy.

[Reason for numerical limitation]

The reasons for the limitations of the present invention will be shown below.

(1) Si 20 to 40% Si is contained to reduce thermal expansion and to improve wear resistance by supplementarily finely precipitated primary and eutectic Si particles. However, if it is less than 20 inches, the reduction in the coefficient of thermal expansion is insufficient, and if it exceeds 40%, the toughness decreases and mechanical properties deteriorate, so it is set at 20 to 40%.

(2) Cul ~4%, Mg 1-2%Cu and M
g improves mechanical properties, especially tensile strength and yield strength, through aging treatment. If any of them is less than 1%, the effect is insufficient, and if Cu exceeds 4% and Mg exceeds 2%, ductility decreases, so Cu was set at 1-4% and Mg was set at 1-2%.

(3) A total of 5 to 10 types of at least one of Fe and Ni, Fe and Ni are the most important elements in the present invention, and form intermetallic compounds of Fe-At and Ni-Al in the matrix. Improves heat resistance.

However, if the total content is less than 5%, the strength and heat resistance will be insufficient, and if it exceeds 10%, the ductility will decrease, so the total content of Fe or Ni is set to 5 to 10%.

(4) Ceramic particles 5 to 20% Ceramic particles include hard particles such as Am Os, Sac, and SlNa, which are dispersed and composited in the above alloy to improve wear resistance and to improve wear resistance. Reduces thermal expansion of the overall invention alloy.

If the composite ratio is less than 5% by weight, sufficient wear resistance cannot be obtained,
If it exceeds 20%, the ceramic particles will aggregate, making it difficult to obtain a uniformly dispersed structure and reducing mechanical properties, so the composite ratio was set at 5 to 20%.

〔Example〕

Hereinafter, a preferred method for manufacturing the alloy according to the present invention will be explained.

First, Si 20-40%, Cu1-4%, Mg1-2
%, and the total amount of Fe or Ni is 5 to 10%, the balance is substantially aluminum, and the aluminum alloy powder has a particle size of 100 mesh or less, Am08, SiC%
5 to 20 pieces of ceramic particles having a particle size of 2 to 30 μm are mixed in, and the mixture is sufficiently stirred and mixed using a mixer.

Next, the mixed powder is sealed in a pure aluminum can, and 1 to 2
Pressing is performed with a pressure of ton/cffl to form a molded body. By setting the value to 1 torV'cj or more, it is possible to reduce the pores between the powders as much as possible to ensure sufficient adhesion, and it is possible to improve the performance of the sintered crystal in the next sintering process. Furthermore, by keeping the pressure below 2 ton/c (2 ton/c), there is an advantage that problems such as the strength of the sealed tube will not be affected.

The edge of the molded body obtained by the above press molding, the molded body is 450
Heating at ~500"C for 1-1.5 hours Push-out processing ratio (
Extrusion processing is performed at an area ratio of 10 to 15 to obtain a billet.

By setting the heating temperature to 450°C or higher, sintering can be sufficiently performed and mechanical properties can be sufficiently ensured, and extrusion resistance can also be low and workability can be ensured. Furthermore, by setting the temperature to 500° C. or lower, grain growth of finely precipitated Si in the aluminum alloy powder can be suppressed, which has the advantage of ensuring outstanding mechanical properties.

By setting the extrusion processing ratio to 10 or more, defects such as pores are eliminated, and the oxide film on the surface of the alloy powder is divided,
Improves matrix adhesion and ensures outstanding mechanical properties. In addition, by setting it to 15 or less, it is possible to keep the extrusion resistance low, suppress the increase in cracks on the billet surface, and ensure excellent workability.

Finally, the fillet obtained by extrusion processing is subjected to T6 heat treatment. T6 heat treatment is performed by holding solution treatment at 500±10° C. for 500.5 hours, followed by water cooling, and holding at 180±10° C. for 18±0.5 hours, followed by air cooling, as specified in JIS.

The present invention will be explained below using specific examples.

First, the particle size is 100% with a Si content of 20 to 40% as shown in Table 1.
High-Si aluminum alloy powder with a particle size of 2 to 30μ
m ceramic hard particles 5-20%-+ mixed in a mixer. Note that Zn and Mn are impurities here.

The mixed powder was sealed in a pure aluminum can, about 1tcn,
Mold with a pressure of W. The molded body is heated at about 450° C. for 1 hour and extruded at an extrusion ratio of about 10 to form a billet.

After solution treatment of the billet at 520℃, 170 to 180
The alloy according to this example (hereinafter referred to as the present alloy) was obtained by performing aging treatment at ℃ for 5 hours.

FIG. 1 shows a schematic diagram of the metal structure of this example.

Wear resistance is improved by uniformly dispersing and compounding the primary and eutectic Si particles 2 and the ceramic hard particles 3 finely precipitated in the aluminum alloy matrix 1.

FIG. 2 shows a photograph of the metal structure of an aluminum alloy containing 30% Si and 10% alumina particles of Example Nα6. In the photograph, the slightly larger black particles are the alumina particles 3, the smaller gray particles are the primary or eutectic Si particles 2, and the white portion is the matrix 1.

The effects of this embodiment described above are as follows.

(1) The wear characteristics of Examples Nα1 to Nα6 are shown in FIG.

The wear amount of the 20% Si aluminum alloy of Example Nα1 was 100
Then, due to high Si, the wear amount will be 10 to 20,
Furthermore, alumina (Am0.) and silicon carbide (SiC)
When 5% or more of ceramic hard particles are composited, the amount of wear is significantly reduced to 1 to 5.

(2) Thermal expansion characteristics of a 20-40% Si alloy with an Nα of 1.5.9, which does not contain ceramic hard particles, and an alloy with an Nα of 2.6.10, which contains 20-40% Si and 10% alumina particles. Shown in Figure 4. The coefficient of thermal expansion decreases as the Si content increases, and further decreases due to the inclusion of alumina particles. The coefficient of thermal expansion of this example Nα2.5.7 containing 20 to 40% Si and 10% alumina particles is 11 to 15.
X 10'/''C, which is almost equivalent to iron-based materials.

Table 1 Table*) 141 is an impurity [Effect of the invention] As explained above, according to the present invention, it has excellent wear resistance and seizure resistance even under severe sliding conditions and lubrication conditions, and It has a small difference in thermal expansion with iron-based alloys, can solve the problem of thermal stress caused by joining with iron or steel, and can provide a wear-resistant aluminum alloy with excellent mechanical properties and easy manufacture.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the metal structure according to this example. Figure 2 shows this example Nα6 with 30% Si and 1 alumina particle.
It is a metallographic photograph of an alloy containing 0 wt%. FIG. 3 is a graph showing the wear characteristics of Examples Nα1 to Nα6. FIG. 4 is a graph showing the thermal expansion characteristics of the Si 20-40% alloy with Nα 1.5.9 and the 5t 20-40% alloy containing 10 wt % of alumina particles with NQ 2.6.10. DESCRIPTION OF SYMBOLS 1... Aluminum alloy matrix, 2... Primary and eutectic Si particles, 3... Ceramic hard particles, 4... Sliding surface.

Claims (1)

[Claims] Si20-40% by weight (hereinafter referred to as %), Cu1-45
, 1 to 2% of Mg, 5 to 10% of at least one of Fe and Ni, and the balance substantially comprised of Al. A wear-resistant aluminum characterized by containing 5 to 20% of ceramic particles in an aluminum alloy. alloy.