JPS62192546A - Production of composite metallic material - Google Patents

Abstract

PURPOSE:To uniformly distribute a granular dispersion material and fibrous dispersion material and to produce a composite material having an excellent sliding characteristic, etc., by preforming said dispersion materials by using a binder and packing a matrix metal into such preform. CONSTITUTION:The fibrous dispersion material 20 such as SiC whiskers and granular dispersion material 10 such as SiC particles are mixed and the mixture composed thereof are put in a mortar 1. The binder such as sodium silicate is sprayed 2 and is mixed therewith under agitation. After such mixture is passed through a sieve 4, the mixture is put into a molding box 5, is compressed by a punch 6 and is heated to form the preform 7. While a metallic mold 5 contg. the preform 7 is kept preheated, a prescribed amt. of a melt 8 of the matrix metal such as Al alloy is poured therein and is pressurized by the punch 6; thereafter, the melt is cooled. The composite metallic material 9 which permits easy polishing, machining, etc., and is uniformly distributed with the dispersion materials is obtd. by the above-mentioned method. The ratio at which the above-mentioned mixture occupies in the composite material is preferably about 10-50vol%.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a metal matrix composite material in which a matrix metal is filled with a dispersion material made of ceramic, carbon, etc. It has a wide range of uses as wear-resistant metallic materials or self-lubricating metallic materials.

[Conventional technology]

Various methods have been known for manufacturing metal matrix composite materials, but high-pressure casting is the most practical method with high productivity. In this method, a fibrous or particulate material, which is a dispersion material, is preformed using a binder or the like so that it has a predetermined shape, and a metal such as aluminum, which is a matrix, is pressed into the preform in a molten state. By impregnating the material, the dispersion material and the matrix metal are composited.

[Two problems to be solved by the invention] However, when the present inventors tried the above-mentioned high-pressure casting method using a particulate dispersion material (hereinafter referred to as particles) such as ceramic particles as a dispersion material, the particles contained a binder. The preformed body made by blending the particles has low strength because the bonding force between the particles is weaker than that made only from the fibrous dispersion material (hereinafter referred to as fiber), and the preformed body is made by impregnating the matrix metal under pressure. The preform is easily destroyed during the process, and if it is destroyed, the final composite material produced will have defects or non-uniform physical properties, which is undesirable. In particular, compared to fibers, there is no bond between dispersed materials due to entanglement, so the strength of a preformed body with a low content of dispersed material is low, and in some cases, there is a problem that it becomes difficult to mold the preformed body. Ta.

[Means for solving problems]

Therefore, in order to solve the above-mentioned problems, the present invention involves forming a mixture of a particulate dispersion material and a fibrous dispersion material into a preform using a binder, and filling the preform with a matrix metal. It employs technical means.

[Effect]

According to the above means, the fibers with a large bulk density can fill the gaps between the particles, and at the same time, the fibers can bond the particles together in a bridging state. Even molded objects with high strength can be manufactured.

〔Effect of the invention〕

Therefore, according to the present invention, it is possible to effectively prevent the formation of defects in the composite material caused by the destruction of the preform, and the metal matrix composite material has excellent characteristics in which the dispersed material is uniformly distributed. can be provided.

〔Example〕

The present invention will be described in detail below based on embodiments shown in white. FIG. 1 is a flowchart explaining the manufacturing method of the metal matrix composite material according to the first embodiment of the present invention in the order of steps.
0 to 200 μ) as 8v01% of the entire metal matrix composite material, SjC particles (particle size 5 to 20 μ, average particle size 10 μ) as the particulate dispersion material 10, and 5ift particles (particle size 5 to 200 μ, average Particle size 25μ) and 20νO1
%, put these mixed and dispersed materials in a mortar l, spray 10% sodium silicate aqueous solution with 20% of the weight of the mixed and dispersed materials using spray 2, and stir and mix thoroughly with pestle 3. did.

Next, this mixed and dispersed material is passed through a 20-mesh sieve 4 to remove dumplings, and then placed in a mold 5, and a punch 6 is used so that the mixed and dispersed material occupies 39 vol% of the cavity in the mold. The mold temperature was set to 10
The temperature was increased to 500℃ at a heating rate of ℃/mtn.
It was held at 0°C for 30 minutes. As a result, a preformed body 7 of the present invention was obtained.

Next, the mold 5 containing this preformed body 7 is preheated to 500°C, and the aluminum alloy (JIS
ADC12) Pour a predetermined amount of molten metal 8, pressurize it with a pressure of 500 kg/- with a bunch 6, maintain the applied pressure until it is sufficiently cooled, and then remove the pressure and demold it to produce a metal matrix composite material 9. was completed.

The metal matrix composite material 9 obtained by the above method has a bending strength of 60 kg/cd, a high degree of HII of 180, and a coefficient of thermal expansion of 12
10-h/"C, and its surface can be polished to a surface roughness of about i, os, making it suitable for use as a sliding member. Also, since it contains a large amount of Sin and particles, it can be easily cut. This composite material 9 can reduce the cost of raw materials by using a large amount of ceramic particles.

In general, particulate dispersion materials such as ceramic particles have a high packing density, so it is difficult to produce a preform with a filling rate of 4Qvol% or less, and even if a large amount of binder is used, at a low filling rate Since the distance is large, the strength of the preform is low, and if a large amount of binder is used, the binder remains in the final composite material, which is undesirable because it causes a decrease in various physical properties of the composite material. 40v for this
By mixing a small amount of fibrous dispersion material into the particles of 0.15 oz or less, the fibers act like a spring and widen the gaps between the particles, thereby lowering the filling rate. By bonding the fibers in a cross-linked manner, it is possible to increase the strength of a preformed body made of particles with a low filling rate, and it is possible to manufacture a preformed body that will not be destroyed even in the subsequent high-pressure casting process. In addition to the role of shaping and solidifying, the binder also plays the role of increasing the grains of the raw material. In other words, when whiskers and particles are mixed, they tend to become partially separated due to their different shapes, but by mixing a binder with appropriate viscosity, the fibers and particles properly adhere to each other and prevent separation. I can do it. Here, fibers are short fibers, milled fibers, or whisker-like fibers with a length of about 10 to 500μ, and the aspect ratio, that is, the ratio of diameter to length, is 50 to 2.
The particles are preferably spherical or irregularly shaped with a size of about 0.05 to 200 μ (in this case, the aspect ratio, that is, the ratio of the longest diameter to the shortest diameter is 10 or less).

Next, a preferred ratio of particles to fibers will be explained based on FIG. 2. Figure 2 shows the volume content of the entire dispersed material,
It is a figure which shows the ratio of the particle|grains and fiber in a dispersion material in the content rate. In the small area A in the figure, a strong preform was obtained, and the composite material produced using this preform showed no defects and exhibited uniform properties, whereas in the area B, the composition Since the particle/fiber ratio is large and the proportion of fibers is small, the effect of the fibers as already explained cannot be fully exhibited. Therefore, due to the insufficient strength of the preform, when it is made into a composite material, it can be visually confirmed that crack-like defects are generated that are made only of matrix metal and do not contain dispersion material, and that thermal expansion Characteristic values such as ratios also varied depending on location. In addition, the filling rate of particles is 50vo
If the amount exceeds 1%, it is possible to produce a preform without fiber, but in order to obtain a stronger preform, a small amount of fiber of 4 vol% or less may be added. In addition, the filling rate of particles is 80
If the amount exceeds vol%, it is difficult to combine. As shown by curves a-b, the relationship between the ratio of particles to fibers and the content of the entire dispersion material is such that the ratio increases as the content of the entire dispersion material increases, and a small amount of fiber is sufficient. Conversely, as the content decreases, a larger amount of fiber is required. When the content of the entire dispersion material is 50 vol%, the respective contents of particles and fibers are 46 vol%, 4 vol%, and 4Q vol%.
When 32vol%, 8vol%, 21vol% when 30vol%, 9vol%, 1 when 20vol%
2v0 when lvol%, 9vol%, 10vol%
1%, 8vol%. That is, the content of fibers in the entire composite material is preferably about 4 to 1 Qvol%.

Next, a second embodiment of the present invention will be described.

Sin, particles (particle size 5-200μ, average particle size 25μ) are 30vol% of the whole composite material, SiC whisker is 3vol%
Weigh out 5 lo of 20% sodium silicate aqueous solution
The two particles and SiC whiskers were added in an amount of 1/10 of the total weight, and mixed by stirring using a known spray dryer. After molding this in a two-part resin mold, it was kept at 800℃ for 30 minutes in a constant temperature bath, and then put into a mold preheated to 300℃ and molten ADC12 at 850℃ was poured at 500 kg/an!
It was pressed in with a pressure of The obtained composite material did not have crack-like defects consisting only of aluminum and exhibited a uniform coefficient of thermal expansion throughout. In addition, this composite material is made of relatively soft SiO□
The machinability was good because it mainly contained particles.

In addition to mixing in a mortar or using a spray dryer, the dispersing material can be mixed using a ball mill, a rotary stirrer, shot blasting, or by suspending the dispersing material in a liquid such as water or alcohol and using a mixer. May be stirred.

In addition to sodium silicate, the binder may contain a small amount of a primary phosphate salt or an organic binder such as PVA. Matrix metal is A1, Cu s
Metals such as Zn-, Sn, Pb, etc. or their alloys, and SiC as a fiber for the dispersion material.

S is Na , Alz O:l , TjBz ,
TIP, whiskers such as potassium titanate, carbon fiber, milled fiber obtained by crushing alumina fiber, particles such as Sic, S1zNa, 5iOz, A
lz 03.

Various ceramic particles such as BN and graphite powder can be used.

[Brief explanation of drawings]

FIG. 1 is a flowchart schematically explaining the method for manufacturing a metal matrix composite material of the present invention, and FIG. 2 shows the relationship between the ratio of particles and fibers to the content of the dispersion material, in which the present invention can be carried out suitably. FIG. 3 is a characteristic diagram showing regions. 7... Preformed body, 8... Matrix metal, 9...
・Metal matrix composite material, lO...particulate dispersion material, 20...
・Fibrous dispersion material. Representative Patent Attorney Takashi Okabe Figure 1

Claims (4)

[Claims] (1) A method for producing a metal matrix composite material, in which a mixture of a particulate dispersion material and a fibrous dispersion material is previously formed into a preform using a binder, and the preform is filled with a matrix metal. (2) The method for producing a metal matrix composite material according to claim 1, wherein the proportion of the mixture in the entire metal matrix composite material is 10 to 50 vol%. (3) The method for producing a metal matrix composite material according to claim 1, wherein the proportion of the fibrous dispersion material in the entire metal matrix composite material is 4 to 10 vol%. (4) The method for producing a metal matrix composite material according to claim 1, wherein the fibrous dispersion material is made of short fibers or whiskers with a length of 10 to 500 μm and has an aspect ratio of 50 to 200. .