JPS63103039A - Manufacture of metal-base composite material - Google Patents

Abstract

PURPOSE:To obtain a composite material in which solid lubricant is uniformly dispersed in a matrix metal, by forming a porous compact by the use of ceramics and either of solid-lubricant constituents and then by impregnating the above with a molten metal containing a matrix metal and the other solid-lubricant constituents. CONSTITUTION:The porous compact consisting of ceramics 4 and one or more kinds among sulfides 5, selenides, and tellurides, as either of solid-lubricant constituents, is placed in a metal mold 8, which is preheated up to about 500 deg.C. Subsequently, the molten metal prepared by melting the matrix metal 1 such as Al, etc., and the other solid-lubricant constituents such as Mo, W, etc., is poured into the above mold, which is pressurized, held under pressure until cooling is started, and then cooled, followed by drawing from the mold. At this time, the constituents such as W, sulfides, etc., are allowed to react to form tungsten disulfide 6, etc., as solid lubricant. It is preferable that the above operations are carried out under the condition kept airtight. In this way, the metal-base composite material suitable for sliding part material can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to fiber or powdered ceramics and solid r4
This invention relates to a method for manufacturing a metal matrix composite material in which a lubricant is dispersed in a matrix metal, and this metal matrix composite material has a wide range of uses as a material for sliding parts without adding a lubricant.

[Prior Art] As a method for producing metal matrix composite materials with higher productivity than conventional methods, a method is known in which a porous molded body made of fiber or powdered ceramic is impregnated with a molten metal containing a matrix metal under pressure. It was getting worse. Furthermore, it is known that dispersing a solid lubricant within the material is effective in imparting self-lubricating properties to this metal matrix composite material. For example, JP-A-61-23704 discloses a metal sintered body containing graphite powder and molybdenum disulfide powder as a sintered solid lubricant member. Composite powder coated with is pressure-molded and sintered at 780° C. for 30 minutes in a decomposed ammonia gas furnace.

[Problems to be Solved by the Invention] The conventional method is sintered in a non-oxidizing atmosphere, which takes time and reduces productivity. Another problem is that solid lubricants undergo oxidative decomposition at high temperatures, requiring a non-oxidizing atmosphere and requiring complicated processes.

An object of the present invention is to produce a metal matrix composite material in which a solid lubricant is uniformly dispersed within a matrix metal without requiring sintering in the non-oxidizing atmosphere described above.

[Means for Solving the Problems] The method for producing a gold l1i single-base composite material of the present invention is characterized in that fibers or powdered ceramics and solid lubricants contain a small amount of sulfide, selenide, and telluride. A molded body forming step of forming a porous molded body with one solid lubricant component consisting of one solid lubricant component, and a matrix metal forming a matrix in the obtained molded body, and at least one of molybdenum and tungsten. A molten metal containing the other solid lubricant component is impregnated, and the one national lubricant component and the other solid lubricant component in the molded body are reacted to obtain the desired solid lubricant and cooled. and a cooling step to obtain a metal matrix composite material in which the ceramic and the solid lubricant are contained in the matrix metal.

The porous molded body formed in the molded body forming process according to the present invention is! ! Made of cloth or powdered ceramics. Ceramics include silicon carbide (S+c)N silicon nitride (Si3Na), aluminum oxide (Adz 03
), titanium boride (TiB2>, titanium phosphide (T
iP), whiskers such as potassium titanate, milled fibers obtained by crushing fibers such as carbon fiber, alumina m-thread, silicon carbide (SiC), silicon nitride (S + 3 N 4 ),
Silicon oxide (Sing), aluminum oxide (A + 2
03) One or more types of granular materials such as N boron nitride (BN>) can be used.The components of the solid lubricant include solid lubricants such as molybdenum disulfide, tungsten disulfide,
Molybdenum selenide, tungsten selenide, molybdenum telluride, a compound containing sulfur, selenium, and tellurium, which are non-gold layer elements of tungsten telluride, sulfides and selenium compounds that form the above solid lubricant in the matrix, At least one type of tellurium compound is used. Sulfides include zinc sulfide (ZnS) and ferrous sulfide (f-esz).
, ferric sulfide (Fed), titanium sulfide (T i
At least one of S t ), titanium sulfide (TizSx), mercury sulfide (HgS), and calcium sulfide (Cab) is used, and selenide and telluride can be similarly used in place of sulfide. In order to form a porous molded body, a required amount of ceramic for the matrix metal and an appropriate amount of at least one of sulfide, selenide, and telluride are mixed and stirred, and then pressure molded.

When the shape of the ceramic used is fibrous, the diameter is 0.
The middle fiber has a diameter of 7μ and an average length of 180μ, and the granular material has a particle size of 2.
Use one with a diameter of 00μ or less. In addition, the sulfide powder has a particle size of 2
00μ or less.

The impregnation cooling process is a process in which the porous molded body is impregnated with molten metal and cooled to solidify the matrix metal, and a molten metal casting method is used. The molten metal casting method is a method in which a porous molded body is placed in a mold, and a matrix metal molten metal is injected under pressure into the mold and impregnated with cold fA solidification. Various pressurizing means can be selected, such as gas, plunger, punch, etc. The pressing force is 500kQ10102 to 1000ko/cm''.

In the cooling process of the matrix metal, the sulfide dispersed in the porous molded body contacts and reacts with the constituent components of the solid lubricant melted in the molten metal under pressure, high temperature, and isolated from air. A solid lubricant is produced and solidified in a dispersed state within the system.

The matrix metal forming the matrix is made of at least one of aluminum, zinc, copper, and magnesium. Therefore, it may be an alloy.

The other solid lubricant component that is melted into the matrix metal is a metal element and is composed of at least one of molybdenum and tungsten. This other solid lubricant component is melted into the matrix metal to form a molten metal. This molten metal is melted into a single liquid phase in a crucible, and the solid lubricant component tungsten or molybdenum in the molten metal contacts with the sulfide of other solid lubricant components in the porous molded body and reacts quickly. Let it proceed. The following is an example of manufacturing a metal matrix composite material in which the matrix metal is aluminum and WSg is dispersed as a solid lubricant. FIG. 7 shows a phase diagram of the A+-W alloy. When the temperature of the molten alloy, which is a single liquid phase at a high temperature, decreases to below the liquid phase 1i1, a solid phase of δ phase begins to precipitate. This in-phase precipitation is
Solids in the δ phase precipitated around ceramics, 1', l because they originate from around ceramics and sulfides with large heat capacities.
The l-agent constituents do not take part in the intended reaction and are wasted, resulting in a decrease in the yield of the solid lubricant. Therefore, the temperature of the molten metal must be sufficiently higher than the liquidus line.

On the other hand, the temperature of the molten aluminum alloy is preferably 1000 to 900°C because oxidation becomes significant when the temperature exceeds 1000°C. Therefore, the upper limit of the amount of tungsten in the alloy is 10%, and therefore the upper limit of the amount of tungsten disulfide produced is 5.5% in terms of volume content. On the other hand, since the pressure-molded porous molded body has a large heat capacity as described above, it is preferable to preheat it in order to allow the reaction to proceed sufficiently.

The porous molded body is housed in a mold and molten metal is injected and impregnated under pressure. After the injection is completed, it is left to cool under pressure. During this time, the solid lubricant components are isolated from the outside world and come into contact with each other, and when ZnS is used as the sulfide, the following reaction proceeds and is uniformly dispersed in the matrix.

W+22nS-+WS2+22n A metal matrix composite material in which a solid lubricant is dispersed is obtained through this impregnation cooling process.

[Example] An example will be described based on process diagrams from FIG. 1 to FIG. 6.

The matrix metal 1 is a molten metal of an alloy of Al-5wt%W (aluminum and tungsten) heated to about 950° C. in a graphite crucible to form a single liquid phase (FIG. 1). The mold 8 includes silicon carbide (SiC) whiskers (diameter 0.05
~1.5μ, length 10~200μ) with a volume content of 20% in the metal matrix composite material 4, and as sulfide 5 zinc sulfide powder (particle size 150μ) in the volume content of the metal matrix composite material A porous molded body (Fig. 3) obtained by stirring and mixing the mixture and press-molding the porous molded products (Fig. 3) is stored and preheated to about 500°C (Fig. 2). The above-mentioned molten matrix metal was poured into this (Figure 4)
Immediately after that, pressurize with plunger 9 at a pressure of 500 kQ/ct2 and maintain the pressurization until it is sufficiently cooled (Fig. 5).
After that, the pressure is removed and the mold is removed. During this pouring and pressurization, the heat of the molten alloy is utilized to cause a reaction between tungsten in the alloy and zinc sulfide to form solid lubricant tungsten disulfide 6 (FIG. 6). Furthermore, since the inside of the mold is isolated from air during pouring, oxidative decomposition of the generated tungsten disulfide does not occur. By this method, a metal matrix composite material containing 2% by volume of the solid lubricant tungsten disulfide was manufactured.

The presence of tungsten disulfide was confirmed by X-ray diffraction method,
Quantification was performed using EPMA and 2% was confirmed.

As another example, an AI-3wt% MO alloy was used as the molten metal, and as in the case above, it was poured into a porous molded body in which the metal matrix composite material had a volume content of 20% and zinc sulfide powder was dispersed at a volume content of 3%. A metal matrix composite material containing 2% by volume of disulfide molybdenum azone was produced by pressurizing hot water.

[Effects] Table 1 compares the manufacturing time and lubricity of the gold-kIJk-based composite material obtained by the manufacturing method of the present invention and that by the conventional method in terms of friction properties. N01 is silicon carbide (
It contained only SiC (SiC) whiskers at a volumetric content of 20% and was produced in the form of water droplets without adding any solid lubricant components. NO2 is a mixture of tungsten disulfide with a volume content of 2% and silicon carbide whiskers with a volume content of 20% and the remainder A1 powder of about 5%.
It was sintered at 00°C in a non-oxidizing atmosphere. No. 3 is the above-mentioned product manufactured using water droplets.

Products manufactured using water droplets do not require a non-oxidizing atmosphere unlike the sintering method, the manufacturing time is shorter, and the particle size of the dispersed solid lubricant is smaller, so the coefficient of friction is smaller than that of the sintering method. It has become.

Table 1 Table 2 The experimental conditions were: the mating material was cast iron (FCD40), surface contact, peripheral speed 2 m/Sec, load 11 kg/c1, and no lubrication.

Table 2 shows the results of measuring the friction coefficients of metal matrix composite materials produced using water droplets with various tungsten disulfide contents.

This shows that the solid lubricant WS2 has a lubrication effect with a volume content of 1% or more.

[Brief explanation of the drawing]

Figure 1 shows the molten metal inside the crucible, Figure 2 shows the porous molded body placed in the mold, and Figure 3 is an enlarged schematic diagram of the porous molded body. Figure 4 shows the injection process of molten metal, Figure 5 shows the impregnation cooling process, Figure 6 is an enlarged schematic diagram of the metal matrix composite material of the present invention, and Figure 7 is a phase diagram of the aluminum-tungsten alloy. be. 1...A I-W alloy molten metal 2...Porous molded body 3...Metal matrix composite material 4...Ceramics 5...Sulfide 6...WSx7...
Crucible 8...Mold 9...Plunger 10...Matrix metal Patent applicant Nippondenso Co., Ltd. Agent Patent attorney Hirodo Okawa Patent attorney Akio Maruyama Figure 4 Figure 5 Figure $7 At 1o 201
OW

Claims (5)

[Claims] (1) Forming a porous molded body with fiber or powdered ceramics and one of the solid lubricant constituents consisting of at least one of sulfides, selenides, and telluride moieties, which are constituent constituents of the solid lubricant. Molded body forming step, impregnating the obtained molded body with a molten metal in which a matrix metal forming a matrix and the other solid lubricant component consisting of at least one of molybdenum and tungsten are melted. One of the solid lubricant components is reacted with the other solid lubricant component to obtain the desired solid lubricant and cooled to form a metal matrix composite material in which the ceramic and the solid lubricant are dispersed in the matrix metal. 1. A method for producing a metal matrix composite material, comprising an impregnating and cooling step. (2) Ceramics include SiC, Si_3N_4, Al
_2O_3, TiB_2, TiP, potassium titanate whisker, carbon fiber, milled fiber made from crushed alumina fiber, SiC, Si_3N_4, SiO_2, Al
The method for producing a metal matrix composite material according to claim 1, comprising one or more types of particles of _2O_3 and BN. (3) Sulfides include ZnS, FeS_2, FeS, TiS
_2, Ti_2S_3, HgS, and CaS. The method for producing a metal matrix composite material according to claim 1. (4) The method for producing a metal matrix composite material according to claim 1, wherein the matrix metal is at least one of aluminum, zinc, copper, and magnesium. (5) The method for manufacturing a metal matrix composite material according to claim 1, wherein in the impregnation cooling step, the molten metal is impregnated under pressure and then cooled.