JPS629173B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an aluminum composite material reinforced with silicon carbide fibers.

Conventionally, research on composite materials of silicon carbide fibers and aluminum or aluminum alloys has been conducted on silicon carbide whiskers and aluminum or aluminum alloys because the silicon carbide fibers in practical use are whisker-like. However, silicon carbide whiskers made only of SiC have poor wettability with aluminum or aluminum alloy, and since the length of the whiskers is only a few mm at most, it is very difficult to align the whiskers, and the tensile strength is low. Because the modulus of elasticity is low and the whiskers are expensive, they are not put to practical use.

The present invention aims to eliminate various drawbacks of the silicon carbide whisker-reinforced aluminum composite material, and to provide a method for producing a silicon carbide fiber-reinforced aluminum composite material that has high tensile strength and high modulus at room temperature and high temperature. For this reason, the present invention was completed by focusing on the fact that when high-strength silicon carbide fibers containing 0.01% or more of free carbon are combined with aluminum or aluminum alloy, the mutual wettability of the two improves.

The silicon carbide fiber containing 0.01% or more of free carbon that can be used in the composite material of the present invention is disclosed in Japanese Patent Application No.
50529, Japanese Patent Application No. 50-52471, and Japanese Patent Application No. 50-52472.

The reason for using silicon carbide fibers containing 0.01% or more of free carbon in the silicon carbide fiber-reinforced aluminum composite material of the present invention is that silicon carbide fibers containing less than 0.01% of free carbon have poor wettability with aluminum or aluminum alloys. Even if a composite material is constructed, there are gaps between the fibers and the metal base when affected by temperature and external forces, so their expansion and contraction cannot be sufficiently suppressed, and they mutually complement each other in strength. This is because it cannot be done.

Best results are obtained in the present invention using silicon carbide fibers preferably containing 2 to 20% free carbon. The elongation and tensile strength of aluminum composite materials in which the silicon carbide fibers containing various amounts of free carbon account for 20% by volume are as shown in Figure 1, as the amount of free carbon in the silicon carbide fibers increases. Accordingly, the elongation of the composite material gradually decreases, and rapidly decreases near 20% free carbon. The tensile strength of the composite material increases as the free carbon content increases, and decreases rapidly below 2% free carbon.

The reason why the tensile strength of the silicon carbide fiber-reinforced composite material containing free carbon of the present invention increases as the amount of free carbon in the fiber increases is that, as shown in the chemical reaction formula (1), This is thought to be because the free carbon contained reacts with aluminum metal to form aluminum carbide, resulting in chemical adhesion in addition to physical adhesion.

4Al+3C→Al ₄ C ₃ ...(1) In the reaction between the free carbon and aluminum, carbon diffuses from the inside of the silicon carbide fiber containing free carbon to the surface, reacts with aluminum, and further flows into the inside of the fiber. As aluminum diffuses and reacts with free carbon, wetting of silicon carbide fibers and aluminum becomes extremely good. The reaction between free carbon and aluminum is extremely fast, but because the diffusion rate of free carbon from inside the silicon carbide fibers and the diffusion rate of aluminum diffusing into the fibers are slow, the reaction between free carbon and aluminum is usually 10 minutes or more. carbon
It is advantageous to carry out the contact reaction with silicon carbide fibers containing 0.01% or more. However, as the amount of free carbon in the silicon carbide fiber increases, the elongation of the composite material decreases because the amount of aluminum carbide in formula (1) increases. According to the micrograph in Figure 2, no pores are observed around the fibers in the composite material obtained through such a chemical reaction, and a thin aluminum carbide layer is observed, indicating that the wettability is I can see that it is getting much better.

The tensile strength, elongation and elastic modulus of the silicon carbide fiber reinforced aluminum composite material of the present invention are as follows:
It varies depending on the volume percentage of silicon carbide fibers in the composite material. In other words, as shown in Figure 3, the tensile strength of silicon carbide fiber-reinforced aluminum composite materials in which the amount of silicon carbide fibers containing 10% free carbon is varied increases as the amount of silicon carbide fibers increases, and the volume increases. When the ratio is 50%, the tensile strength is approximately 10 times higher than that of aluminum. However, the elongation of the composite material is as shown in FIG.
As the amount of silicon carbide fiber increases, the elongation becomes smaller than that of aluminum, and the volume ratio becomes 80
If the amount of silicon carbide fiber added is more than 2%, the elongation of the composite material is almost nonexistent, and if the amount of silicon carbide fiber added is less than 2%, the tensile strength is almost the same as that of aluminum.

As shown in Figure 5, the elastic modulus of the silicon carbide fiber aluminum composite material increases as the amount of fiber increases, and when the content is 50% by volume, it is about three times that of aluminum. It's summery.

Furthermore, the silicon carbide fiber-reinforced aluminum composite material of the present invention has high strength even in the high temperature range of 200 to 600°C, so it can be used. In other words, as shown in Figure 6, the tensile strength of a silicon carbide fiber-reinforced aluminum composite material containing 10% free carbon in the high temperature range up to 600°C decreases as the temperature rises, but the tensile strength of aluminum is extremely low. 400℃
It has a large value of about 95 Kg/mm ² even at 600°C, and it is also about 90 Kg/mm ² at 600°C, making the composite material a material that can be used reliably even at high temperatures.

In the silicon carbide fiber-reinforced aluminum composite material of the present invention, an element whose standard free energy change (ΔG°) when reacting with carbon to form carbide has a negative value as shown in Figure 7 is added to the aluminum metal. It can be made into an alloy and combined with silicon carbide fiber to make a composite material. The added elements include hafnium, zirconium, titanium, vanadium, chromium, silicon, manganese, molybdenum, niobium, tantalum,
Tungsten, these elements can react with the free carbon in the silicon carbide fibers to create stable carbides at low temperatures, further improving the wetting of the fibers with the alloy. In addition to the above-mentioned elements, iron, copper, and nickel combine with SiC, so these elements can be added to aluminum or aluminum alloy to improve wetting of the silicon carbide fibers and the metal.

However, if large amounts of iron and/or copper are added to aluminum, the SiC will decompose and the silicon carbide fibers will lose their shape.
% or less.

Next, the method for manufacturing the composite material of the present invention will be explained.

The silicon carbide fibers containing 0.01% or more of free carbon used in the present invention are listed below (1) to (10).
It is manufactured using organosilicon compounds classified as starting materials.

(1) Compounds containing only Si—C bonds.

(2) Compounds containing Si-H bonds in addition to Si-C bonds.

(3) Compounds with Si-Hal bonds.

(4) Compounds with Si—N bonds.

(5) Compounds with Si-OR (R-alkyl, aryl) bonds.

(6) Compounds with Si—OH bonds.

(7) Compounds containing Si—Si bonds.

(8) Compounds containing Si-O-Si bonds.

(9) Organosilicon compound esters.

(10) Organosilicon compound peroxide.

From at least one organosilicon compound belonging to the types (1) to (1) and (10) above, silicon is produced by a polycondensation reaction using at least one of irradiation, heating, and addition of a polycondensation catalyst. An organosilicon polymer compound having carbon as a main skeleton component, for example, a compound having the following molecular structure is produced.

(d) Those containing the skeleton components described in (a) to (c) above as at least one partial structure of a chain or three-dimensional structure, or a mixture of (a), (b), and (c).

Examples of compounds having the above molecular structure include the following.

n=1, poly(silmethylene siloxane) n=2, poly(silethylene siloxane) n=6, poly(silphenylene siloxane) n=1, poly(methyleneoxysiloxane) n=2, poly(ethyleneoxysiloxane) n=6, poly(phenyleneoxysiloxane) n=12, poly(diphenyleneoxysiloxane) n = 1, polysilmethylene n = 2, polysilethylene n = 3, polysiltrimethylene n = 6, polysilphenylene n = 12, polysildiphenylene (d) as described in (a) to (c) above Those containing a skeleton component as a partial structure in at least one of chain, cyclic, and three-dimensional structures, or a mixture of (a), (b), and (c).

Spinning the organosilicon polymer compound, preheating the spun yarn in a vacuum, and then firing it at a high temperature in a vacuum or in an atmosphere of one or more selected from inert gas, CO gas, and hydrogen gas. This makes it possible to produce silicon carbide fibers with extremely high strength and high elastic modulus.

The ratio of silicon and carbon contained in the organosilicon polymer compounds (a) to (d) above, which are the raw materials for the silicon carbide continuous fibers, is such that at least 5 atoms or more of carbon and 2 atoms of silicon are contained. Therefore, when this organosilicon polymer compound is spun and fired, many of the carbons bonded as side chains of the polymer turn into hydrocarbons and volatilize, but at least
0.01% or more can remain in the silicon carbide fiber as free carbon.

In conventionally known composite materials of silicon carbide whiskers and aluminum or aluminum alloys, the whiskers and metal are only physically bonded, but in the composite material of the present invention, free particles in silicon carbide fibers are bonded to each other. Carbon and metal elements also chemically combine to form carbides as shown in formula (2) below.

C+Al=AlC...(2) Furthermore, by a hot pressing method, silicon carbide fibers containing at least 0.01% or more of free carbon are brought into contact with aluminum or aluminum alloy in a solid phase and hot pressed to combine the free carbon and aluminum. This makes it possible to produce composite materials with improved wettability. In this case, silicon carbide fibers containing 0.01% or more of free carbon and metal aluminum powder are brought into contact with each other in the solid phase and hot pressed, and the temperature range is 300 to 660 to cause the free carbon and aluminum to react and improve wetting.
℃ is good. If the temperature range is below 300°C, the reaction between free carbon and aluminum is extremely slow and is not practical, and above 660°C, aluminum melts, so the best results can be obtained in the range of 300 to 600°C.
The pressure of the hot press is in the range of 0.1 to 10 tons/cm ² , and if it is less than 0.1 tons/cm ² there is no pressurizing effect, and if it is pressurized more than 10 tons/cm ² it will not be effective, so the pressure is 0.1 ~10 tons/ ^cm2 . Additionally, hot pressing time is related to temperature and is usually
10 minutes or more at 660℃, 16 minutes or more at 600℃, 500℃
Hot press for at least 38 minutes at above temperatures, at least 85 minutes at 400℃, and at least 200 minutes at 300℃.

The methods of hot pressing to composite silicon carbide fiber and aluminum include (1) foil metallurgy, (2) powder metallurgy, (3) electrodeposition, (4) plasma spray, and (5) vapor deposition. be.

(1) The foil metallurgy method involves wrapping metal foil and fibers around a drum while fixing them with a binder to create a layer of foil and fibers, which is then removed from the drum and cut into an appropriate shape and hot pressed.

(2) Powder metallurgy involves forming a mold by stacking metal powder and rows of fibers alternately, or by applying a vacuum from one end of a bundle of fibers and packing the powder into a certain shape, or by combining short fibers and metal powder. This method involves rolling or extruding a molded product into a molded product, and then hot pressing this molded product.

(3) The electrodeposition method is a method in which a matrix metal is attached to fibers by electrolytic deposition and the fibers are hot-pressed into a predetermined shape.

(4) The plasma spray method is a method in which metal powder is injected into a plasma arc in an inert atmosphere, and the powder is sprayed onto aligned fibers and then hot-pressed.

(5) Vapor deposition is a method in which metal is attached to the surface of fibers by vacuum deposition or chemical vapor deposition, then bundled and hot pressed.

Among the various hot pressing methods mentioned above, in the powder metallurgy method, after press-molding fibers and metal powder,
It is also possible to improve wetting by sintering in the temperature range of 300 to 660° C. without pressure, but in this case heating must be carried out for a longer time than in hot pressing.

Next, examples of the present invention will be explained.

Example 1 A net made of approximately 250 meshes of silicon carbide fibers containing 10% free carbon and having a diameter of 10 to 15 μm and aluminum powder were heated to a temperature of 600°C and 5 tons/cm ² in an argon atmosphere. A silicon carbide fiber-reinforced aluminum alloy composite material was obtained by hot pressing for 40 minutes under pressure. The composite material contained 21% by volume of silicon carbide fibers and had a strength of 54 kg/cm ² .

The silicon carbide continuous fiber-reinforced aluminum or aluminum alloy composite material obtained by the method of the present invention has extremely high tensile strength and high elastic modulus, and is therefore used as various materials shown below.

(a) Materials for synthetic fibers, such as bobbins, separators, threaders, pump parts, balls, sleeves, mechanical seals, valves, nozzles, agitators, reaction vessels, pipes, heat exchangers, valves, etc.

(b) Materials for synthetic chemistry, such as plunger pumps, sleeves, mechanical seals, separators, reactor valves, pressure reducing valves, seats, heat exchangers, centrifuges,
Low temperature containers, etc.

(c) Materials for mechanical industry, such as heat exchangers, powder dies, ultrasonic processing machines, horns, sewing machine parts, cams, ball mill parts, camera parts, vacuum pumps, current collectors, bearings, tools, clock parts, machine stands ,others.

(d) Materials for household and office supplies, such as desks, various shelves, chairs, various lockers, etc.

(e) Materials for construction machinery, such as boring machines;
Jackhammers, crushers, caterpillars, sand pumps, power shovels, etc.

(f) Emergency parts, such as sprinklers, ladders, etc.

(o) Materials for marine development (including space), such as heat exchangers, antennas, water markers, tanks, etc.

(h) Automotive materials, such as engines, manifolds, differential carriers, crankcases, pump bodies, valve bodies, crankcases, clutch housings, transmission cases, gearboxes, flyhole housings, cylinder blocks, cylinder heads, pistons, pulleys, pumps. Bodies, blower housings, tire molds, rotary engines, structural materials, body materials, etc.

(i) Food grade materials such as super decanters, valves, reactors, mechanical seals, separators, etc.

(j) Sports materials, such as spikes, golf equipment, tennis rackets, fishing equipment, mountaineering equipment, ski equipment, badminton rackets, poles, etc.

(k) Materials for marine aircraft, such as engines, structural materials, external walls, screws, hydrofoils, etc.

(l) Electrical materials such as power transmission cables, capacitors, chassis, antennas, stereo parts, poles, etc.

(m) Building materials, such as window frames, structural materials, etc.

(n) In addition to the above, materials for agricultural machinery, materials for fishing gear, materials for nuclear power, materials for nuclear fusion reactors, materials for solar heat utilization,
Materials for medical equipment, materials for bicycles, valves,
It can be advantageously used for valve seats, rings, rods, disks, liners, inventors, parts for pumps for transporting earth and sand, parts for waste disposal equipment, dies for extrusion of plastics, nozzles, reflectors, etc.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the amount of free carbon contained in silicon carbide fibers and the elongation and tensile strength of silicon carbide fiber reinforced aluminum composite materials. Figure 2 shows the relationship between the amount of free carbon contained in silicon carbide fibers and the elongation and tensile strength of silicon carbide fiber reinforced aluminum composite materials. Figure 2 shows the relationship between the amount of free carbon contained in silicon carbide fibers and the elongation and tensile strength of silicon carbide fiber reinforced aluminum composite materials. A micrograph of an aluminum composite material. Figure 3 is a diagram showing the relationship between the tensile strength of a silicon carbide fiber-reinforced aluminum composite material containing 10% free carbon and the volume ratio of fibers in the composite material. Figure 4 is a diagram showing the relationship between the tensile strength of a silicon carbide fiber-reinforced aluminum composite material containing 10% free carbon. A diagram showing the relationship between the elongation of a silicon carbide fiber-reinforced aluminum composite material containing 10% and the volume ratio of fibers in the composite material,
Figure 5 is a diagram showing the relationship between the elastic modulus of a silicon carbide fiber-reinforced aluminum composite material containing 10% free carbon and the volume ratio of fibers in the composite material, and Figure 6 is a diagram showing the relationship between the elastic modulus of a silicon carbide fiber-reinforced aluminum composite material containing 10% free carbon, and Figure 6 is a diagram showing the relationship between the elastic modulus of a silicon carbide fiber reinforced aluminum composite material containing 10% free carbon, and Figure 6 shows the relationship between the elastic modulus of a silicon carbide fiber reinforced aluminum composite material containing 10% free carbon and the volume ratio of the fibers in the composite material. FIG. 7 is a diagram showing the temperature change in the tensile strength of the reinforced aluminum composite material and the temperature change in the tensile strength of aluminum, and FIG. 7 is a diagram showing the standard free energy change in the carbide production reaction.

Claims (1)

[Scope of Claims] 1. Silicon carbide fibers containing 0.01% or more free carbon produced by firing spun fibers made of organosilicon polymer compounds whose main skeleton components are silicon and carbon, and aluminum metal or alloy. A method for producing a silicon carbide fiber-reinforced aluminum composite material, which comprises contacting and hot-pressing in a solid phase at a volume ratio of 20 to 98% aluminum and 80 to 2% silicon carbide fiber. 2 Silicon carbide fibers containing 0.01% or more free carbon produced by firing spun fibers made of organosilicon polymer compounds whose main skeleton components are silicon and carbon, and aluminum metal or alloy at a volume ratio of 20% aluminum ~98%, silicon carbide fiber 80~2%, and elements that have good wettability with carbon and silicon carbide such as hafnium, zirconium, titanium, vanadium, chromium, silicon, manganese, molybdenum, niobium, tantalum, A method for producing a silicon carbide fiber-reinforced aluminum composite material, which comprises adding at least one selected from tungsten, iron, copper, and nickel to aluminum in a weight ratio of 20% or less, contacting the aluminum in a solid phase, and hot pressing. .