JP2007270340A - Metal-ceramic composite material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a large-sized metal-ceramic composite material capable of suppressing the occurrence of a crack and enhancing a manufacturing yield. <P>SOLUTION: The metal-ceramic composite material 10 of which the principal surface has a size greater than 200 mm × 200 mm, and in which the crack of ≥3 mm in length does not exist on this surface is manufactured by (A) a process of manufacturing a perform 11 consisting of ceramics and having the size of the principal surface of 200 mm × 200 mm or more, (B) a process of arranging a stress buffer member 12 on the circumference of the perform 11, and installing these into a molten metal pressurizing apparatus 13, (C) a process of pressurizing and penetrating the molten metal 24 into the perform 11, and (D) a process of removing the excess metal sticking to the surface of a massive object 15 obtained by the pressurization penetration treatment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a metal-ceramic composite material and a method for producing the same, and more particularly to a large metal-ceramic composite material comprising aluminum or an aluminum alloy produced by a pressure infiltration method and engineering ceramics such as SiC, and a method for producing the same. .

  A metal-ceramic composite material composed of a metal material as a matrix and a ceramic material as a reinforcing material is an excellent material that combines the rigidity and wear resistance of ceramic materials with the ductility and toughness of metal materials. Its application development is being actively carried out.

  For example, a composite material made of an aluminum alloy and silicon carbide (SiC) powder is lightweight and can increase the specific Young's modulus, which is a value obtained by dividing the Young's modulus by the density. And has excellent vibration damping characteristics, and can be suitably applied to, for example, a high-speed moving arm of a robot.

As a method for producing such a metal-ceramic composite material, generally, a molded body (hereinafter referred to as “preform”) is manufactured using ceramic powder, and this is placed in a molten metal pressurizing apparatus. A method in which molten metal is pressed and infiltrated is used (for example, see Patent Document 1).
When a metal-ceramic composite material is produced by such a pressure infiltration method, a method of using an excess amount of molten metal in addition to the amount necessary for infiltration into the space inside the preform is used. Therefore, excess metal solidifies on the surface of the metal-ceramic composite material after the pressure infiltration treatment.

Here, in general, the metal-ceramic composite material and the metal solidified on the outer surface thereof have different thermal expansion coefficients. For example, when SiC powder is used as the ceramic powder, the filling rate is 70% by volume, and an aluminum alloy is used as the metal material, the thermal expansion coefficient of the aluminum alloy is about 20 × 10 ⁻⁶ / ° C. On the other hand, the thermal expansion coefficient of the metal-ceramic composite material is about 8 × 10 ⁻⁶ / ° C. Therefore, when the aluminum alloy solidifies on the outer surface of the metal-ceramic composite material in the cooling process after pressurizing and infiltrating the molten aluminum alloy into the SiC preform, -Stress may be applied to the ceramic composite material, which may cause cracks. In particular, in a large metal-ceramic composite material having a main surface shape of 200 mm × 200 mm or more and a thickness of 10 mm or more, the probability of occurrence of this problem is extremely high, and the manufacturing yield is lowered.
Japanese Patent Laid-Open No. 01-142244

  The present invention has been made in view of such circumstances, and a metal-ceramic composite material manufacturing method capable of suppressing the occurrence of cracks and increasing the manufacturing yield, and a metal-ceramic composite material manufactured by this manufacturing method. The purpose is to provide.

  The metal-ceramic composite material having a metal and ceramic provided by the present invention has a main surface having a size of 200 mm × 200 mm or more and no crack having a length of 3 mm or more on the surface. Is a metal-ceramic composite material. “The main surface has a size of 200 mm × 200 mm or more” means a size in which a square of 200 mm × 200 mm fits in the main surface.

  As the ceramic, any of silicon carbide, silicon nitride, aluminum nitride, sialon, aluminum borate, and alumina is preferable, and as the metal, aluminum or an aluminum alloy is preferable.

  The present invention also provides, as a method for producing such a metal-ceramic composite material, a step of producing a preform made of ceramics and having a main surface size of 200 mm × 200 mm or more, and stress around the produced preform. Place the buffer members and install them inside the molten metal pressurizing device, make the molten metal pressurize and infiltrate the preform, and adhere to the surface of the lump obtained by this pressurization treatment There is provided a method for producing a metal-ceramic composite material comprising a step of removing excess metal.

  The ceramic powder and metal for manufacturing the preform are as described above. As the stress buffer member, a thin plate made of any material selected from iron, copper, and carbon is suitable. The gap provided between the preform and the stress relaxation member is preferably 0.1 mm or more and 30 mm or less.

  According to the present invention, a metal-ceramic composite material having a main surface having a size of 200 mm × 200 mm or more can be produced with high yield while suppressing the occurrence of cracks.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a method for producing a metal-ceramic composite material (hereinafter simply referred to as “composite material”) according to the present invention.

  The manufacturing method of the composite material 10 includes (A) a step of manufacturing a preform 11 made of ceramic powder and having a main surface size of 200 mm × 200 mm or more, and (B) a stress buffer member 12 around the preform 11. And (C) the molten metal 14 is pressed and infiltrated into the preform 11 and then cooled, and then the mass 15 to be produced is added to the molten metal. A step of taking out from the pressure device 13, and (D) a step of removing excess metal adhering to the surface of the obtained lump 15.

Ceramic powders preferably used in the step (A) include silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), sialon, aluminum borate (9Al ₂ O ₃ .2B ₂ O ₃ ) And engine rearing ceramics such as alumina (Al ₂ O ₃ ). The ceramic powder is generally granular, such as a sphere, but may be a fibrous material. The ceramic powder may be a whisker or a mixture of these different forms.

  As a method of forming the preform 11 by forming the ceramic powder, an organic binder is added to the ceramic powder and mixed, and this is formed into a predetermined shape by a press forming method. A solvent such as water is added to the ceramic powder. Various powder forming methods such as a method of forming by a filter press and a method of laminating a plurality of green sheets produced by using a sheet forming method such as a doctor blade method and thermocompression bonding can be used. When the preform 11 has a complicated shape, an injection molding method can also be used.

  The size of the main surface of the preform 11 is 200 mm × 200 mm or more. When the size of the main surface is smaller than this, it is possible to manufacture the composite material by suppressing the occurrence of cracks in the composite material 10 without arranging the stress buffer member 12. “The size of the main surface of the preform 11 is 200 mm × 200 mm or more” means that a 200 mm × 200 mm square is accommodated in the main surface, for example, a rectangular shape having a main surface shape of 200 mm × 150 mm. Reforms are not included, but preforms having a circular main surface with a diameter longer than a 200 mm × 200 mm square circumscribed circle are included. The thickness of the preform 11 is not particularly limited. However, if the thickness is small, warping is likely to occur after the completion of the step (C). For example, the thickness is preferably 10 mm or more.

  In addition, it is preferable to set the molding conditions of the preform 11 so that the ceramic content in the finally obtained composite material 10 is 40% by volume or more and 80% by volume or less. This is because when the ceramic content in the composite material 10 is less than 40% by volume, it is not possible to effectively exhibit the excellent characteristics of ceramics such as high rigidity and wear resistance, while this ceramic content is 80 volume. This is because it is difficult to mold the preform 11 that exceeds%.

  (B) The step is (B-1) a method in which the stress buffering member 12 is arranged around the preform 11 and these are placed inside the molten metal pressurizing device 13, and (B-2) the preform 11 is molten. Any method of placing the pressure buffering member 12 around the preform 11 and then placing the stress buffer member 12 around the preform 11 may be used. Further, in these methods, the preform 11 and the stress buffering member 12 are heated to a predetermined temperature (hereinafter referred to as “preheated state”) in a state where the preform 11 and the stress buffer member 12 are installed inside the molten metal pressurizing device 13. It is preferable.

  The molten metal pressurizing device 13 has a lower die 13a and an upper die 13b for putting a sample, and a pressing device (not shown) such as a hydraulic device for applying a constant pressure thereto. “Installing the preform 11 and the stress buffering member 12 inside the molten metal pressurizing device 13” means that “the preform 11 and the stress buffering member 12 are placed inside the lower mold 13 a constituting the molten metal pressurizing device 13. It means “install”.

  As the stress buffer member 12, a material that does not easily react with the molten metal 14 and is easily peeled off when the molten metal 14 is cooled and solidified is used. For example, when the molten metal 14 is an aluminum alloy, a thin plate made of any material selected from iron, copper, and carbon is preferably used. The thin plate includes a film (foil) shape and a sheet shape, and in consideration of shape retaining property, ease of handling and the like, a thickness of 0.3 mm to 10 mm is preferable. As the stress buffer member 12, it is preferable to select a material whose shape is not greatly collapsed by the heat of the molten metal 14 used in the subsequent step (C).

  If the preform 11 is completely sealed with the stress buffer member 12, the molten metal 14 cannot penetrate into the preform 11, and an injection port for introducing the molten metal 14 into the stress buffer member 12 is provided. This portion is provided on the stress buffer member 12.

  Further, when the stress buffer member 12 is in close contact with the preform 11, the penetration of the molten metal 14 into the preform 11 is hindered. Therefore, it is preferable to provide a gap of 0.1 mm or more and 30 mm or less between the preform 11 and the stress buffer member 12. If this gap exceeds 30 mm, the amount of excess metal that solidifies on the surface of the composite material 10 after the pressure infiltration treatment increases, and cracks occur in the composite material 10 due to the difference in the thermal expansion coefficient between inside and outside. It becomes easy. Further, when the gap is less than 0.1 mm, a portion where the molten metal 14 does not penetrate into a part of the preform 11 is easily formed. However, a part of the stress buffer member 12 is allowed to come into contact with the preform 11 as long as the molten metal 14 can be favorably penetrated into the preform 11.

  In addition, as shown in FIG. 1, it is not necessary to arrange | position the stress buffer member 12 in the bottom face side of the preform 11, but you may arrange | position. In FIG. 1, a self-standing thin plate 12 a is provided as a stress buffering member 12 so as to surround the side surface of the rectangular flat plate-shaped preform 11, and the thin plate 12 b in which the injection port 12 c is formed does not contact the upper surface of the preform 11. Thus, the form constructed in the middle part of the self-supporting thin plate 12a is illustrated. When the thin plate 12b in which the injection port 12c is formed is thin and easily bent, if the thin plate 12b is provided with a beam, the thin plate 12b can be prevented from bending and coming into contact with the preform 11. .

  The reason why the preform 11 and the stress buffering member 12 are preferably preheated when the preform 11 and the stress buffering member 12 are installed inside the molten metal pressurizing device 13 is that the preform 11 and the stress buffering member 12 are at room temperature, In the process, when the molten metal 14 is introduced, a part of the molten metal 14 is cooled and solidified on the surfaces of the preform 11 and the stress buffer member 12, and the penetration of the molten metal 14 into the preform 11 is prevented. This is because there is a possibility that the molten metal 14 is cooled by the preform 11 and its viscosity is increased, which may prevent the molten metal 14 from penetrating into the preform 11.

  However, when the predetermined amount of molten metal 14 is put into the lower mold 13a of the molten metal pressurizing device 13, the preform 11 is warmed, and once solidified metal is melted again, so that the penetration into the preform 11 is hindered. When it becomes a state which cannot be performed, preheating of the preform 11 and the stress buffer member 12 is not necessary. As a method for that purpose, for example, even if the molten metal 14 is deprived of heat by the heating of the preform 11, the initial temperature should be secured so that the temperature at which the penetration into the preform 11 sufficiently proceeds is secured. That's fine.

  When the method (B-1) is used as the preheating method for the preform 11 and the stress buffer member 12, the preform 11 and the stress buffer member 12 provided around the preform 11 are heated to a predetermined temperature, and thereafter It is sufficient to install it integrally in the molten metal pressurizing device 13. When the method (B-2) is used, the preform 11 and the stress buffer member 12 are heated to a predetermined temperature, and the preform 11 and the stress buffer member 12 are then placed inside the molten metal pressurizing device 13. May be arranged sequentially.

The preheating temperature of the preform 11 and the stress buffer member 12 is determined in consideration of the ease of handling and the temperature of the molten metal 14. For example, when the temperature of the molten metal 14 is T ₁ ° C, the preheating temperature of the preform 11 can be set to T ₁ -200 ° C or higher and T ₁ ° C or lower.

  Step (C) is a so-called pressure infiltration method or high pressure casting method, in which the molten metal 14 is charged into the lower mold 13a and a certain pressure is applied to the molten metal 14 using the upper mold 13b. As a result, the molten metal 14 penetrates into the preform 11 and the preform 11 is combined.

  As the molten metal 14 used here, aluminum (pure aluminum) or an aluminum alloy is suitable. As the aluminum alloy, an aluminum-silicon (Al-Si) alloy or an aluminum-magnesium (A1-Mg) alloy is used. Can be mentioned. In that case, the melting temperature is preferably 700 ° C. or higher and 1000 ° C. or lower, and more preferably 750 ° C. or higher and 900 ° C. or lower. If the temperature is less than 700 ° C., the penetration of the molten aluminum alloy is likely to occur, and penetration failure is likely to occur. If the temperature is 1000 ° C. or higher, the molten aluminum alloy is likely to be oxidized.

  When molten aluminum or a molten aluminum alloy is used as the molten metal 14, the preheating temperature of the preform 11 is preferably 500 ° C or higher and 1000 ° C or lower, and can be 700 ° C or higher and 800 ° C or lower.

  The pressure at which the molten metal 14 is pressed and infiltrated into the preform 11 is generally 10 MPa or more and 100 MPa or less, although it depends on the viscosity of the molten metal 14. If this pressure is less than 10 MPa, poor penetration tends to occur, and if it exceeds 100 MPa, the molten metal 14 may spill from the upper and lower molds 13 a, 13 of the molten metal pressurizing device 13.

  After pressurizing for a certain period of time, the pressurized state is released, and the lump 15 as a sample is cooled to a constant temperature and taken out. At this time, the gap formed between the preform 11 and the stress buffer member 12 before the step (C) is filled with the metal solidified by the step (C). The solidified metal is also attached to the outside. That is, the lump 15 to be taken out is in a state in which excess metal adheres around the composite material 10 formed by the molten metal 14 penetrating into the preform 11. In the lump 15, the stress applied to the composite material 10 due to the difference in coefficient of thermal expansion between the composite material 10 and excess metal around the composite material 10 is relieved by the stress buffer member 12. 10 can be prevented from being distorted or cracked.

  In the subsequent step (D), the excess metal is removed from the block 15 and the composite material 10 is taken out. In this step, grinding is preferably used. When the gap formed between the preform 11 and the stress buffering member 12 in the previous step (B) is wide, it is also preferable to use a method in which cutting is performed first and then grinding is performed. In the case where a slight amount of metal on the surface of the composite material 10 is removed, such a chemical solution may be used when the metal is dissolved in a predetermined chemical solution.

  By such a manufacturing method, the composite material 10 having a main surface having a size of 200 mm × 200 mm or more and a length of 3 mm or more and having no cracks can be manufactured with a high yield. “No crack having a length of 3 mm or more” refers to two states in which there is no crack at all or the length is less than 3 mm even if a crack has occurred.

  Note that, as described above, as a lower mold of the molten metal pressurizing device that accommodates the preform 11, the gap between the inner wall and the outer periphery of the preform 11 is set between the preform 11 and the stress buffer member 12 as described above. When a composite material is manufactured without using the stress buffer member 12 and a material equivalent to the gap to be formed is used, the molten metal 14 injected between the preform 11 and the lower mold is caused by the mold. There is a problem in that it is cooled and solidified, which impedes the penetration of the molten metal 14 into the preform 11. Further, since the preform 11 does not have high strength, it is difficult to place the preform in a preheated state in such a small lower mold without damaging it, and the production yield is lowered.

(1) Manufacture of composite materials according to examples Commercially available SiC powder (manufactured by Shinano Denki Smelting, average particle size 60 μm): 70 parts by weight, SiC powder (manufactured by Shinano Denki Smelting, average particle size 10 μm): 30 wt. To the part, PVB (polyvinyl butyral): 5 parts by weight (external ratio) and colloidal silica: 5 parts by weight (external ratio) are added as binders, and this is pressed to a size of 800 mm long × 200 mm wide × 20 mm high Then, a preform having a filling rate of SiC powder of 60% by volume was produced.

  Subsequently, an iron plate having a thickness of 1 mm was placed around the manufactured preform as a stress buffer member with a 1 mm gap between the preform and the iron plate, and these were preheated to 700 ° C. The preheated preform and the iron plate were taken out and placed in the mold of the molten metal pressurizing apparatus so that they were in the same form as in the preheat treatment. This installation form is the form shown in FIG.

  Separately, an aluminum alloy (JIS AC8A) is melted at 750 ° C., and this molten aluminum alloy is put into a mold in which a preform and a stress buffer member are arranged, and a pressure of 30 MPa is applied to obtain a molten aluminum alloy. Infiltrated into the preform. This infiltration treatment was performed for 10 minutes. Then, the lump containing the composite material was taken out from the mold. In this lump, it was considered that the aluminum alloy solidified around the composite material was divided at the iron plate portion, and the stress applied to the composite material when the molten aluminum alloy contracted was alleviated.

  The excess aluminum alloy adhering to the periphery of the composite material was removed from the lump obtained in this way by grinding to obtain a composite material having the same shape as the preform. No cracks were observed on the surface of this composite material.

(Characteristic evaluation of composite materials according to examples)
The bulk density of the obtained composite material was determined by the method defined in JIS-R1634. As a result, it was confirmed that the bulk density was as small as 3.0 g / cm ³ and lightweight. Further, a test piece of 100 mm × 25 mm × 2 mm was cut out from the obtained composite material, and the Young's modulus was determined by the method defined in JIS-R1602 using the test piece. As a result, the Young's modulus was as large as 220 GPa and high rigidity. Thus, the obtained composite material had the characteristics of having both the high rigidity of SiC and the light weight of an aluminum alloy.

(Comparative example)
The same material and the same shape preform as the above embodiment, using the same molten metal pressure device, the same conditions as in the above embodiment, except that a steel plate as a stress buffer member is not provided around the preform, A composite material was produced. As a result, it was confirmed that many cracks having a length of 3 mm or more were generated on the surface of the obtained composite material.

The figure which shows typically the manufacturing method of a metal-ceramics composite material.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Metal-ceramics composite material, 11 ... Preform, 12 ... Stress buffer member, 12a ... Self-supporting thin plate, 12b ... Thin plate, 12c ... Injection port, 13 ... Molten metal pressurizing device, 13a ... Lower metal mold, 13b ... Upper metal Mold, 14 ... molten metal, 15 ... lump.

Claims (7)

A metal-ceramic composite material having a metal and a ceramic,
A metal-ceramic composite material, characterized in that its main surface has a size of 200 mm × 200 mm or more and no crack of 3 mm or more in length exists on the surface. The ceramic is one of silicon carbide, silicon nitride, aluminum nitride, sialon, aluminum borate, and alumina,
The metal-ceramic composite material according to claim 1, wherein the metal is aluminum or an aluminum alloy. A step of manufacturing a preform made of ceramics and having a main surface size of 200 mm × 200 mm or more;
Placing stress buffer members around the manufactured preform and installing them inside the molten metal pressurizing device;
A step of pressure infiltrating the molten metal into the preform;
And a step of removing excess metal adhering to the surface of the lump obtained by the pressure permeation treatment.   The method for producing a metal-ceramic composite material according to claim 3, wherein the preform has a main surface having a size of 200 mm × 200 mm or more.   The metal according to claim 3 or 4, wherein the ceramic powder is silicon carbide, silicon nitride, aluminum nitride, sialon, aluminum borate, or alumina, and the metal is aluminum or an aluminum alloy. -Manufacturing method of ceramic composite material.   The method for producing a metal-ceramic composite material according to any one of claims 3 to 5, wherein the stress buffer member is a thin plate made of any material selected from iron, copper, and carbon. .   The method for producing a metal-ceramic composite material according to any one of claims 3 to 6, wherein a gap of 0.1 mm to 30 mm is provided between the preform and the stress relaxation member. .

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