JPH02254105A - Production of aluminum-alloy composite material - Google Patents

Abstract

PURPOSE:To economically improve the wear resistance and friction coefficient of the material with high efficiency by cutting or grinding the composite material with an Al alloy obtained by powder metallurgy as the matrix and then blasting the surface. CONSTITUTION:Al alloy powder is mixed with granular or short fibershaped ceramic or a hard metal alloy other than Al, and the obtained mixed powder is pressed and compression-molded. The molded product is hot-extruded or sintered. The Al alloy obtained by powder metallurgy is used as the matrix, and the grains or short fibers are dispersed in the matrix to obtain a composite material. The composite material is cut or ground into a specified shape and dimensional precision. The surface of the composite material is then blasted. Consequently, a part of the soft matrix layer is removed from the surface, the hard grains, etc., are allowed to protrude from the surface, the matrix is hardened, the effect in retaining the hard grains is enhanced, and the wear resistance and friction coefficient are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Fields] The present invention is applicable to aluminum alloy composite materials that require good wear resistance and a high friction coefficient, such as paper feed rollers and steel belt drive boots. This invention relates to a method for manufacturing materials.

[Prior art] Conventionally, as a method for manufacturing a composite material having a surface layer that requires good wear resistance and a high coefficient of friction,
As disclosed in No. 7-44864, the surface of an aluminum boob is finished by machining, and a hard ceramic or metal such as chromium oxide, alumina, tungsten, or tungsten carbide is formed thereon as a coating using a solvent. is proposed. Furthermore, as disclosed in JP-A-63-158356, after mixing and dissolving curable additive particles in a non-curing material, the mixture is molded into a cylindrical pulley shape, and the additive particles are heat-treated for curing. A method of manufacturing a pulley has been proposed, which is characterized in that the material is corroded so that additive particles protrude from the pulley surface.

In the former method, it is difficult to control the thickness of the coating, and the uniformity is insufficient, making it unsatisfactory for use as a part of a driving device for precision machinery.

In addition, in the latter method, the interface between the additive particles and the raw metal is also susceptible to corrosion due to chemical corrosion, and the gripping effect of the 7 Trixes on the additive particles becomes insufficient. If an attempt is made to increase the degree of protrusion, this tendency becomes stronger, resulting in disadvantages such as the tendency for oil-added particles to fall off.

[Problems to be Solved by the Invention] The present invention improves the drawbacks of the prior art as described above, increases the bonding strength between the matrix layer and the added hard particles, improves the wear resistance, and improves the coefficient of friction. The purpose of this invention is to economically provide an aluminum alloy composite material having three thick surface layers.

[Means for solving problems] The present invention will be explained in detail below.

The present invention was achieved as a result of various studies on surface treatment methods in order to solve the problems of the prior art.As shown in Fig. 1, ceramic particles or hard metal particles other than aluminum are added to aluminum or aluminum alloy powder. A composite material is obtained using a powder metallurgy method using a blended powder as a raw material, and then cutting or grinding is performed as necessary, and then the surface layer is blasted to prioritize the soft matrix layer. It is characterized by removing a part of the hard ceramic or metal alloy particles or short fibers from the matrix.

A conventional powder metallurgy method can be used to obtain a composite material of aluminum or aluminum alloy. That is, the first method is to compression mold a powder obtained by blending aluminum or aluminum alloy powder with ceramic particles or hard metal particles other than aluminum using a hydrostatic press or hydraulic press to form a billet for extrusion.
By performing hot extrusion, it is made into solid or hollow materials with various cross-sectional shapes.

The second method is to blend powder of aluminum or aluminum alloy powder with ceramic particles or hard metal particles other than aluminum, compression molding with a mechanical or hydraulic press, and sintering to form a powder compact close to the final product shape. do.

Next, the extruded material or molded product obtained in this way is machined, such as cutting, cutting, or grinding, as necessary to finish it into a predetermined shape and dimensional accuracy. Furthermore, by blasting, the soft matrix layer is preferentially abraded and removed, causing the hard particles to protrude from the surface. Since the blasting method is a dry surface treatment method, even if there are some bores as in the case of the molded article according to the second method, the problem of corrosive liquid remaining in the bores does not occur. In addition, in the conventional etching method, the interface between the matrix and the hard particles tends to be preferentially eroded, and the gripping effect of the hard particles on the matrix tends to weaken, whereas in the plasting method, the surface layer of the matrix is subjected to work hardening and residual compressive stress further enhances the gripping effect on hard particles, making it less likely that problems such as falling off during use will occur.

According to the first method among the above manufacturing methods, the molded body IIIj
The il is dense, the matrix (aluminum or aluminum alloy N) and the hard particles are strongly bonded, and a good surface layer with excellent wear resistance can be obtained. On the other hand, many machining operations are required to obtain the final product shape. According to the second method, since a molded article having a shape close to the final product can be produced, there is an advantage over the first method that cutting and grinding are not required, or even if they are necessary, the extent thereof is small. In particular, composite materials including ceramics can be cut and
Since grinding is difficult and expensive, the second method is cost-effective. On the other hand, the second method has a density of 90
~98%, some of the bores remain, and the bonding strength between the matrix layer and the hard particles is weak. As described above, both methods have advantages and disadvantages, and a method can be selected from among these methods in consideration of required characteristics, cost, etc.

Next, we will discuss matters to be kept in mind when determining the materials, blending amounts, etc. of ceramic and hard metal particles or short fibers used in the present invention.

(b) Hard particle types and amounts For example, types of hard particles include alumina, silica, titania, mullite, spinel, 5iC1WC, TiC,
Metallic silicon, SUS, 30'4, Fe-Cr alloy, etc. can be used.

The blending amount of these hard particles or short fibers is 3 to 30V.
% of VO, preferably 5 to 20 VO1%, is suitable. 3v
If the dispersion is less than 0.1%, the abrasion resistance due to dispersion will not be sufficiently blued, and if the dispersion is less than 30VO1%.
-C, especially when the second powder metallurgy method is used, the relative density (volume ratio/theoretical density ratio) #) of molding 14 is less than 90%, defects such as bores are significantly increased, and the Madnox layer (
Since the bond strength between the hard particles and the aluminum (aluminum or aluminum alloy layer) is significantly weakened, good mechanical properties cannot be obtained.

(a) Uniform dispersibility and particle size Select a material that can be easily dispersed uniformly in aluminum and aluminum composite V5). In order to do this, it is necessary to select the most recent one and the next one, and it is also necessary to select the particle size so that the particle size does not differ greatly.

It is necessary to select the particle size according to the required surface image (elongation).
・In the case of ＼ruto drive booby, the protrusion height of the hard particles from the matrix surface varies from 50 to 100μ and U.
10 to 507) is considered appropriate.

−・Generally, the smaller the particle size, the smaller the coefficient of friction.
Also, it is easy to fall off from the trix. On the other hand, from the viewpoint of processability, if the particle size is too large, it will be easy to separate from the matrix alloy, making it difficult to produce a composite material in which hard particles are uniformly dispersed in the matrix. Taking these into consideration, the particle size should be 500 mesh (25μ) or more, 20 mesh (
It is preferable to select from the following range: 840 μ) or less.

In addition, in order to firmly hold the hard particles in the matrix, it is desirable that the particle diameter be at least twice the required protrusion height of the hard particles from the 7-trix surface; Select to satisfy the conditions.

Note that it is also possible to use short fiber-shaped particles instead of hard particles, if necessary.

Next, let me explain about the plastic treatment method.

The blasting material used during the blasting process can be made of ceramics such as alumina, SiC, or metals such as stainless steel or carbon steel. In order to efficiently grind the surrounding area, a blasting material with a smaller particle size than the hard particles is used.

When using a hard ceramic material such as alumina or SiC as the blasting material, the discharge pressure of the blasting material should be lowered to avoid grinding the dispersed hard particles themselves. In that case [discharge pressure is 1 to 3 kgf/cm'
It is desirable to do so.

On the other hand, by using stainless steel or carbon steel blasting materials, a relatively wide range of blasting conditions (blasting pressure, discharge amount, discharge time, discharge distance) can be achieved.
It has been found that it is possible to stably and easily obtain the target surface state, that is, a state in which the hard particles are firmly gripped by the matrix layer and are appropriately protruded. (FIG. 3) [Embodiments of the Invention] [Embodiments of the present invention] [Embodiments of the present invention] [Embodiments of the present invention] will be explained below.

(Example) With the raw material composition shown in Table 1, a powder-molded composite material in the shape of a pulley shown in FIG. 2 was created according to the steps shown in FIG. After grinding, using a 100-mesh stainless steel grid and a U220-mesh alumina as the material I, the discharge pressure was 5 I (g/c) in each case.
m 2 and 3) cg/cm 2 (Furano) treatment was applied, and part of the matrix layer was removed by polishing. Plast was carried out while rotating the sample, and the total plast time was 15 seconds in both cases.

Table 1 Aluminum alloy composite (composition of materials) As a result of cutting and polishing a composite material sample prepared under the above conditions and observing its cross section with a scanning electron microscope, the protrusion height of the hard particles from the matrix surface was both In addition, in both cases where stainless steel or alumina was used as the blasting material, a surface layer in which the hard particles 2 were firmly adhered to the 7trix 3 could be easily obtained as shown in Fig. 3. It was confirmed that

A steel heald was attached to the composite material thus obtained, and a 1,000-hour actual test was carried out, and the cross-sectional structure of the sample after the test was observed in the same manner as the sample before the test. As a result, no hard particles were observed to fall off from the samples after the test in any case. Further, even when the pulley was moved back and forth, no slippage between the pulley and the heald was observed, confirming that the surface layer had excellent wear resistance and a high coefficient of friction.

(Comparative Example) A powder-molded composite material was prepared in the same manner as in Example-1, and 5% NaO was added to the outer peripheral surface layer of this composite material.
An etching step was performed using a Hyk solution. At that time, the liquid temperature was 50°C and the time was 5 minutes.

As a result of cutting and polishing the composite material made with the above-mentioned conditions and observing the cut surface with a scanning electron microscope, it was found that the etching solution permeated around the hard particles 6 during the etching process, as shown in Figure 5. Locations 5 where the layer was corroded to the depths and hard particles had fallen off, and locations where hard particles were likely to fall off were observed.

The sample obtained in this manner was also subjected to an actual machine test in the same manner as in Example-1, and the cross-sectional structure of the sample after the test was observed. As a result, it was confirmed that more than half of the remaining hard particles had fallen off.

[Effects of the Invention] By applying the present invention, the soft matrix layer is preferentially scraped off, and some of the hard ceramic or metal alloy particles or short fibers are made to protrude from the matrix 1, and moreover, into the trix. By increasing the adhesion strength of hard particles of It becomes possible to manufacture materials with high efficiency and economically.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the process of the present invention, Fig. 2 is a diagram showing the appearance of a hollow cylindrical powder compact used in the present invention, and Fig. 3 is a diagram showing an example of the process of the present invention. Figure 4 shows the cross-sectional structure of a molded body when steel blasting material is used. Figure 4 shows the cross-sectional structure of a molded body when alumina is used as the blasting material. Figure 5 shows the cross-sectional structure of a molded body when alumina is used as the blasting material. Figure 5 shows the cross-sectional structure of a molded body when steel blasting material is used. FIG. Figure 1 Figure 2 Figure 1 - Blast or etching surface 2 - Hard particles (
3- Matrix layer (aluminum or aluminum alloy layer) 4- Bore 5- Location where hard particles (alumina) fall off

Claims (1)

[Claims] A step of obtaining a composite material using an aluminum alloy as a matrix and dispersing ceramics in the form of particles or short fibers or a hard metal/alloy other than aluminum by a powder metallurgy method, a step of cutting or grinding the composite material, and a step of cutting or grinding the composite material; A method for producing an aluminum alloy composite material, which comprises subjecting the surface layer of the composite material to blasting.