JP4252161B2 - Method for producing metal-based composite material using liquid phase sintering - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a metal-based composite material using liquid crystal sintering in which ceramic fibers or metal fibers are used as reinforcing short fibers and a metal material is used as a matrix material.
[0002]
[Prior art]
Conventionally, as a method of manufacturing a liquid crystal sintered metal composite materials utilizing, a method described in JP-A-58-136735, also by the method described are known in JP 62 -67141 Patent Publication Yes.
In these methods, as shown in FIG. 4, HIP (hot isostatic pressing) is performed by using eutectic alloy 73 in matrix metal particles 72 themselves or a part thereof mixed in reinforcing fibers 71 in the mixing step. ) The metal-based composite material 76 in a state in which the matrix metal 75 wraps the reinforcing fibers 71 is manufactured by liquid crystal sintering using the apparatus 74.
For example, in the one described in JP-A-58-136735, an aluminum eutectic alloy, aluminum and an aluminum eutectic alloy, or a metal that forms aluminum and an aluminum eutectic alloy is used as a matrix material. A carbon fiber reinforced aluminum composite material is manufactured by mixing with carbon fiber and pressing at a temperature below the melting point of aluminum. Here, the eutectic alloy 73 is used for the matrix metal particles 72 per se or a part thereof, mainly to keep the sintering temperature low, and to improve the adhesion between the reinforcing fibers 71 and the matrix metal 75. It is because it aims to do.
[0003]
[Problems to be solved by the invention]
However, the conventional method for producing a metal-based composite material still has the following problems to be solved.
When the metal-based composite material 76 is manufactured using silicon carbide as the reinforcing fiber 71 and titanium or titanium alloy (Ti-6Al-4V) powder as the matrix metal particle 72, the silicon carbide and titanium are wetted at the interface. Since a reaction phase composed of TiC (titanium carbide) that has poor properties (adhesiveness) and has a problem in strength depending on conditions is produced, sufficient composite strength can be obtained when both are combined as a composite material. Therefore, it was extremely difficult to obtain a strength suitable as a composite material.
[0004]
The present invention was made in view of such circumstances, and liquid crystal sintering capable of improving the interfacial strength between the reinforcing short fibers and the matrix material and suppressing the generation of a reaction phase having a problem in strength. An object of the present invention is to provide a method for producing a metal-based composite material using the above.
[0005]
[Means for Solving the Problems]
A method for producing a metal-based composite material using liquid crystal sintering according to the present invention in accordance with the above object is a metal using liquid phase sintering in which a metal material is a matrix material and ceramic fibers or metal fibers are reinforcing short fibers. A method for producing a composite material comprising:
A copper or cobalt coating layer is formed on the reinforcing short fibers, the matrix material is capable of generating a eutectic alloy phase with the coating layer, and the matrix material and the reinforcing short fibers are mixed, performing liquid phase sintering at the conditions said matrix material and said coating layer to produce a eutectic alloy phase. Accordingly, it is possible to obtain a good interface between the reinforcing short fibers and the matrix material, which are bonded by metal bonding.
[0006]
The concept behind the present invention will be described in detail.
Generally, it is used for reinforcing short fibers rather than metal materials that form a matrix material. For example, ceramics have higher strength and melting point, but a mixture of ceramic short fibers and matrix metal powder uniformly mixed is sintered. At this time, when heated to the melting point of the matrix metal powder or higher, the matrix metal powder is liquefied, and as a result, the ceramic short fibers having a low density move upward by buoyancy, so that a uniform mixed sintered body cannot be obtained. In some cases, the strength of the ceramic short fibers and the obtained mixed sintered body is lowered due to the reaction between the liquid metal and the ceramic short fibers (generation of intermetallic compounds, etc.).
[0007]
Therefore, when a mixture in which ceramic short fibers and matrix metal powder are uniformly mixed in advance is heated to a temperature range lower than the melting point of the matrix metal powder by HIP (isotropic pressure heating) treatment, etc., and simultaneously pressurized. It is considered that a high-quality solid-phase sintered body can be obtained. However, in this solid-phase sintering, the matrix metal powder partially plastically flows when held at a sintering temperature for a certain period of time, and metal atoms mutually diffuse at the interface between the matrix metal powders. Sintering is achieved. On the other hand, when the reinforcing short fibers are ceramics, generally, the ceramics are covalent bonds and the metals are free-electron metal bonds if classified according to the bonding form based on the electronic structure, so the interface between the ceramic short fibers and the matrix metal powder. So, by combining them,
(1) There is no reaction and an anchor effect is generated only by the plastic flow of the matrix.
(2) Intermetallic compounds (carbides, nitrides, oxides, etc.) are produced by the reaction and become brittle and the strength decreases.
(3) Some atoms undergo a substitution reaction,
The interface strength generally decreases. Further, even when the reinforcing short fiber is a metal, if the melting point of the metal is high, the sintering time is short, and the diffusion coefficient is small, sufficient interface strength may not be obtained.
[0008]
In order to solve the above problems, in the present invention, first, a matrix metal powder (matrix material) and a low melting point eutectic alloy can be first prepared on the surface of a ceramic short fiber used as a reinforcing short fiber. 3 metals (copper or cobalt in this embodiment) are coated. FIG. 2 shows a Cu—Ti phase diagram, and FIG. 3 shows a Co—Ti phase diagram. In FIG. 2, the density ρ _{A at} the eutectic point A (875 ° C.) of copper-titanium is 7.419 (gf / cm ³ ), and the density ρ _{B at} the eutectic point B of copper-titanium (960 ° C.) is 6. 075 in (gf / cm ^3), and FIG. 3, the cobalt - titanium density [rho _C of the eutectic point C (1170 ° C.) of 7.579 (gf / cm ^3), cobalt - eutectic point of titanium D (1020 The density ρ _D at 5.degree. C. is 5.287 (gf / cm ³ ).
[0009]
Next, the liquid phase sintering method of the present invention will be described in comparison with the conventional liquid phase sintering method.
First, in the conventional liquid phase sintering method, a matrix metal powder and a third metal powder that forms a eutectic alloy are previously weighed and mixed so as to have a eutectic composition ratio. A ceramic short fiber is added as a fiber, mixed and sintered. In this case, since the matrix metal powder completely becomes a eutectic alloy and liquefies, unless the sintering time is shortened, the ceramic short fibers with low density move upward due to buoyancy, and a uniform mixed sintered body is obtained. I can't. Further, when liquid phase sintering is performed by hot pressing or HIP treatment, a heat-resistant capsule is required, and it is necessary to select a capsule material that does not react with the liquefied eutectic alloy.
[0010]
The difference between the liquid phase sintering method of the present invention and the conventional liquid phase sintering method is that part of the matrix metal powder becomes a eutectic alloy and liquefies, and not all of it becomes a eutectic alloy. There is no point. That means
(1) By coating the surface of the reinforcing short fibers with a third metal that forms a eutectic alloy with the matrix metal, at the time of sintering, the eutectic alloy is generated only around the reinforcing short fibers, At the interface between the matrix particles, there is a solid-phase sintered part due to the mutual diffusion of metal atoms of the matrix.
(2) By coating the surface of the reinforcing short fiber and the surface of the matrix metal powder with a third metal that forms a eutectic alloy with the matrix metal, not only around the reinforcing short fiber but also between the matrix particles A eutectic alloy can also be formed at the interface of the material and sintered. At this time, the central part of the matrix particles is not eutectic and therefore not liquefied.
[0011]
Here, the coating layer can also be formed by a mechanical alloying method, thereby enabling easy and inexpensive coating.
Moreover, the diameter of the reinforcing short fiber can be set to 0.5 to 1 μm and the length can be set to 10 to 200 μm, and a high-strength metal-based composite material can be manufactured. The reason why the diameter of the reinforcing short fiber is 0.5-1 μm is that if it is less than 0.5 μm, there is a problem that the fiber breaks during the mixing process, whereas if it exceeds 1 μm, it becomes larger than the matrix particles There is a problem that uniform mixing is not possible. Further, the length of the reinforcing short fibers is set to 10 to 200 μm. If the length is less than 10 μm, there is a problem that the function as the fiber reinforcing material is lost. On the other hand, if the length exceeds 200 μm, the fibers are entangled during the mixing process. There is a problem of forming clusters.
Further, the mixing ratio of the reinforcing short fibers to the metal-based composite material may be 2 to 30 wt%.
Further, titanium or a titanium alloy can be used as the matrix material, and silicon carbide fibers can be used as the reinforcing short fibers, whereby a light and high strength metal composite material can be produced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
FIG. 1 is a flow diagram of a method for manufacturing a metal-based composite material using liquid phase sintering according to an embodiment of the present invention.
[0013]
As shown in FIG. 1, in the method for manufacturing a metal-based composite material using liquid phase sintering according to an embodiment of the present invention, mechanical allo is applied to the surface of silicon carbide fiber 10 which is an example of a reinforcing short fiber. Copper (or cobalt) 11 is pressure-bonded and coated by ing (MA, that is, a mechanical alloying method). The coated silicon carbide fiber 12 coated with copper (or cobalt) 11 and a titanium alloy (Ti-6Al-4V) powder 13 which is an example of a matrix material (metal material) are mixed and then the mixture is molded and mixed. After forming the pressure molding material 14, heat deaeration and sealing (not shown) are performed, and liquid crystal sintering is performed by a HIP processing (liquid crystal sintering) device 15, so that the interface state between the titanium alloy 16 that is the matrix material and the silicon carbide fiber 10. The ceramic reinforced metal-based composite material 17 having a good quality is manufactured. Hereinafter, it will be described in detail with reference to FIG.
[0014]
The diameter of the silicon carbide (SiC) fiber 10 of ceramic material which is lighter than the matrix material and has high strength is 0.5 to 1 μm and the length is 10 to 200 μm. As the reinforcing short fibers, other ceramic short fibers other than silicon carbide (SiC) can be used, and further, metal short fibers can be used as necessary. In addition to ceramic short fibers or metal short fibers, ceramic whiskers or metal whiskers can be used. Considering the reinforcement by the crosslinked structure, the aspect ratio (diameter to length ratio) of the reinforcing short fibers is adjusted to be 20 or more, and the length of the reinforcing short fibers is the particle size of the matrix metal powder. It is adjusted to be larger, preferably at least twice the particle size.
[0015]
The particle size or size of copper (or cobalt) 11 used for mechanical alloying is 45 μm. For example, the coated silicon carbide fiber 12 is formed by applying pressure to the surface of the silicon carbide fiber 10 using an attritor or planetary mill and coating. To do. The thickness of the coating layer is 0.1 to 1 μm. Therefore, the volume ratio of the copper (or cobalt) 11 to the coated silicon carbide fiber 12 is 18 to 77%. The amount of coating of copper (or cobalt) 11 can be produced in the case of the MA method using an attritor or the like, and silicon carbide (SiC) fiber 10, a matrix material, and a matrix material and a eutectic alloy can be produced in advance. Make a proper amount.
As a coating method, in addition to mechanical alloying, a PVD (Physical Vapor Deposition) method, a CVD (Chemical Vapor Deposition) method, or other methods may be used.
[0016]
The particle size of the titanium alloy powder 13 that is the base of the titanium alloy 16 that is a lightweight high-strength metal is about 30 to 150 μm. In addition to the titanium alloy powder 13, titanium powder as a source of titanium can be used, and other metal materials such as magnesium, aluminum, and alloys thereof can also be used.
The mixing weight ratio of the silicon carbide fiber 10 to the metal-based composite material 17 is 2 to 30 wt%, and the mixing treatment is performed using a V-type mixer.
This mixture is molded at a pressure of 800 to 1400 kgf / cm ² and a temperature of 20 ° C. using a universal testing machine (press machine) to form a mixed pressure molding material 14. As shown in the figure, the coated silicon carbide fiber 12 and the titanium alloy powder 13 in the mixed pressure-formed material 14 are in a state in which the particles of the titanium alloy powder 13 cover the periphery of the coated silicon carbide fiber 12.
[0017]
After the encapsulated mixed pressure forming material 14 is processed in the heat degassing enclosure (canning) process, it is stored in the pressure vessel 18 of the HIP (hot isotropic pressure) processing device 15 and is installed in the pressure vessel 18. The mixed pressure-molded material 14 is subjected to HIP treatment in a high-temperature, high-pressure gas 19 (950 ° C., 1000 atm) under an isotropic pressure by a heated heater (not shown) and a gas 19 introduced into the pressure vessel 18. Thus, the ceramic reinforced metal composite material 17 is manufactured.
By this HIP treatment, as shown at the bottom of FIG. 1, a reaction phase (liquid phase) 20 of copper (or cobalt) and titanium is first formed by a reaction between copper (or cobalt) 11 and titanium alloy powder 13. Next, the eutectic alloy phase 21 of copper (or cobalt) and titanium is generated by the reaction between the reaction phase (liquid phase) 20 of copper (or cobalt) and titanium and the titanium alloy powder 13. Reference numeral 22 represents titanium.
[0018]
By coating copper (or cobalt) 11 capable of forming a titanium alloy and a eutectic alloy on the surface of the silicon carbide fiber 10, the eutectic alloy phase 21 is formed only around the silicon carbide fiber 10 during liquid phase sintering. Without being formed, a solid phase sintered portion is present at the interface between the titanium alloy powders 13 due to mutual diffusion of metal atoms of the matrix. At the same time, the performance of the starting titanium alloy powder 13 is relatively well maintained.
[0019]
Therefore, as shown in the upper side of FIG. 1, the ceramic reinforced metal composite material 17 has a good interface state in which the silicon carbide fibers 10 are dispersed in the titanium alloy 16 that is a matrix. Moreover, since the production amount of the liquid phase can be calculated in advance, the thickness of the liquid phase (the thickness of the eutectic alloy phase 21) can be controlled. As a result, the liquid phase of the eutectic alloy has good wettability with the silicon carbide fiber 10, so that it penetrates into the recesses of the surface roughness of the silicon carbide fiber 10 and exhibits a good anchoring effect after solidification.
Further, if necessary, both the surface of the silicon carbide fiber 10 and the surface of the titanium alloy powder 13 are coated with copper (or cobalt) 11 capable of forming a titanium alloy and a eutectic alloy. The eutectic alloy phase can be generated not only at the periphery but also at the interface between the titanium alloy powders 13 to be sintered. At this time, the center part of the titanium alloy powder 13 particles is eutectic. And therefore does not liquefy.
[0020]
【Example】
A method for producing a ceramic reinforced metal composite material by applying a method for producing a metal composite material using liquid phase sintering according to an embodiment of the present invention will be described.
The silicon carbide fiber 10 having a diameter of 0.5 to 1.0 μm and a length of 10 to 200 μm is used, and the particle size of copper (or cobalt) 11 is 45 μm or less. The coated silicon carbide fiber 12 having a coating layer thickness of 0.1 to 1.0 μm was formed by pressure-bonding to the surface of the coating. The volume ratio of the copper (or cobalt) 11 to the coated silicon carbide fiber 12 was 18 to 77%.
[0021]
The titanium alloy powder 13 is composed of 89.5% Ti, 6.14% Al, 3.93% V 2, a particle size of less than 150 μm, and a metal-based composite material 17 of silicon carbide fiber 10. The mixing weight ratio to 2 to 30 wt%.
This mixture was molded using a press at a pressure of 800 to 1400 kgf / cm ² and a temperature of 20 ° C., and the mixed pressure-molded material 14 was processed into a eutectic crystal using a HIP (hot isostatic pressing) processing device 15. The ceramic reinforced metal-based composite material 17 was manufactured by liquid phase sintering at a temperature of + 50 ° C. and 1000 atm for 30 minutes.
[0022]
In the method for producing a metal-based composite material using liquid phase sintering according to an embodiment of the present invention, the following can be considered.
(1) Silicon carbide by sintering with a titanium alloy as a matrix material using coated silicon carbide fibers obtained by mechanically press-bonding copper or cobalt to silicon carbide fibers (short reinforcing fibers) by mechanical alloying A ceramic reinforced metal-based composite material with improved wettability (adhesion) at the interface with titanium can be produced.
(2) The interface state between the silicon carbide fiber and the copper or cobalt of the coating layer is considered to be better than that of the silicon carbide-titanium alloy interface due to the anchor effect or the like. Generation of a reaction phase with silicon can be suppressed by the coating layer.
(3) Since copper or cobalt forms a eutectic alloy phase between the coating layer and the matrix by liquid phase sintering with the matrix titanium, a good interface bonded by metal bonding can be obtained.
[0023]
【The invention's effect】
In the method for producing a metal-based composite material using liquid phase sintering according to claims 1 to 5, a good interface between the reinforcing short fibers and the matrix material bonded by metal bonding can be obtained. Metal-based composite materials with improved strength can be manufactured.
In particular, in the method for producing a metal-based composite material using liquid phase sintering according to claim 2, since the coating layer is formed by a mechanical alloying method, coating can be performed easily and inexpensively. Manufacturing costs can be reduced.
In the method for producing a metal-based composite material using liquid phase sintering according to claim 3, since the diameter and length of the reinforcing short fibers are defined, a metal-based composite material having excellent mechanical strength can be produced. .
In the method for producing a metal-based composite material using liquid phase sintering according to claim 4, since the mixing ratio of the reinforcing short fibers to the matrix material is controlled within a predetermined range, the mechanical strength can be easily controlled. Become.
In the method for producing a metal-based composite material using liquid phase sintering according to claim 5, since titanium or a titanium alloy is used as a matrix material and silicon carbide fiber is used as a reinforcing short fiber, it is light and strong. A ceramic-reinforced metal-based composite material having a high height can be produced.
[Brief description of the drawings]
FIG. 1 is a flow diagram of a method for producing a metal-based composite material using liquid crystal sintering according to an embodiment of the present invention.
FIG. 2 is a Cu—Ti phase diagram.
FIG. 3 is a Co—Ti phase diagram.
FIG. 4 is a flowchart of a method for manufacturing a metal-based composite material using liquid crystal sintering according to a conventional example.
[Explanation of symbols]
10: silicon carbide fiber, 11: copper (or cobalt), 12: coated silicon carbide fiber, 13: titanium alloy powder, 14: mixed pressure molding material, 15: HIP treatment (liquid crystal sintering) device, 16: titanium alloy 17: Metal-based composite material, 18: Pressure vessel, 19: Gas, 20: Reaction phase (liquid phase), 21: Eutectic alloy phase, 22: Titanium

Claims (5)

A method for producing a metal-based composite material using liquid phase sintering with a metal material as a matrix material and ceramic fibers or metal fibers as reinforcing short fibers,
A copper or cobalt coating layer is formed on the reinforcing short fibers, the matrix material is capable of generating a eutectic alloy phase with the coating layer, and the matrix material and the reinforcing short fibers are mixed, A method for producing a metal-based composite material using liquid phase sintering, characterized in that liquid phase sintering is performed under conditions where the coating layer and the matrix material generate a eutectic alloy phase.   The method of manufacturing a metal-based composite material using liquid phase sintering according to claim 1, wherein the coating layer is formed by a mechanical alloying method. Production method.   3. The method for producing a metal-based composite material using liquid phase sintering according to claim 1 or 2, wherein the reinforcing short fibers have a diameter of 0.5 to 1 [mu] m and a length of 10 to 200 [mu] m. A method for producing a metal-based composite material using liquid phase sintering.   In the manufacturing method of the metal type composite material using liquid phase sintering of any one of Claims 1-3, the mixing ratio with respect to the said metal type composite material of the said reinforcing short fiber shall be 2-30 wt%. A method for producing a metal-based composite material using liquid phase sintering.   In the manufacturing method of the metal type composite material using liquid phase sintering of any one of Claims 1-4, titanium or a titanium alloy is used as said matrix material, and a silicon carbide fiber is used as said short fiber for reinforcement | strengthening. A method for producing a metal-based composite material using liquid phase sintering.

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