Aluminum-silicon-carbide composite and method of manufacturing same

Abstract

Provided are an aluminum-silicon-carbide composite having high thermal conductivity, low thermal expansion, and low specific gravity and a method for producing the composite. Provided is an aluminum-silicon-carbide composite formed by impregnating a porous silicon carbide molded body with an aluminum alloy. The ratio of silicon carbide in the composite is 60 vol % or more, and the composite contains 60-75 mass % of silicon carbide having a particle diameter of 80 m or more and 800 m or less, 20-30 mass % of silicon carbide having a particle diameter of 8 m or more and less than 80 m, and 5-10 mass % of silicon carbide having a particle diameter of less than 8 m.

Claims

1. An aluminum-silicon-carbide composite formed by impregnating a porous silicon carbide molded body with an aluminum alloy, wherein a ratio of the silicon carbide in the composite is 60 vol % or more; and the composite contains: 60-75 mass % of silicon carbide having a particle diameter of 80 m or more and 800 m or less; 20-30 mass % of silicon carbide having a particle diameter of 8 m or more and less than 80 m; and 5-10 mass % of silicon carbide having a particle diameter of less than 8 m, wherein the aluminum-silicon-carbide composite has a thermal conductivity of 230 W/mK or more at 25 C.

2. The aluminum-silicon-carbide composite according to claim 1, having a coefficient of thermal expansion of 7.0 ppm/K or less at 25 C. to 150 C.

3. The aluminum-silicon-carbide composite according to claim 1, wherein the aluminum alloy contains 10 to 14 mass % of silicon and 0.5 to 2.5 mass % of magnesium.

4. The aluminum-silicon-carbide composite according to claim 2, wherein the aluminum alloy contains 10 to 14 mass % of silicon and 0.5 to 2.5 mass % of magnesium.

Description

EXAMPLES

Example 1

(1) Weighed were 65 mass % of a silicon carbide powder having a particle diameter of 80-800 m, 25 mass % of a silicon carbide powder having a particle diameter of 8 m or more and less than 80 m, 10 mass % of a silicon carbide powder having a particle diameter of less than 8 m, 8.9 mass % of colloidal silica (Snowtex O manufactured by Nissan Chemical Industries, Ltd., containing 20 mass % of solid content), and 12 mass % of water, which were mixed to prepare a slurry. This slurry was poured into a plaster mold and was left to stand and was then demolded and dried to obtain a molded body. This molded body was fired in air at 1000 C. for 4 hours into a preform.

(2) As the silicon carbide powder having a particle diameter of 80-800 m, NG-F80 manufactured by Pacific Rundum Co., Ltd. was used.

(3) As the silicon carbide powder having a particle diameter of 8 m or more and less than 80 m in an amount of 25 mass % and the silicon carbide powder having a particle diameter of less than 8 m in an amount of 10 mass %, a powder prepared by mixing GC-#500 manufactured by Nanko Abrasives Industry Co., Ltd., GC-1000F manufactured by Yakushima Denko Co., Ltd., and GC-#4000 manufactured by Nanko Abrasives Industry Co., Ltd. at a blending ratio of 13.5:16.5:5.0 was used.

(4) A part of the preform was processed into a diameter of 50 mm and a thickness of 5 mm for measuring the density. The filling degree of silicon carbide of the preform was 69.6%. The filling degree of silicon carbide of the preform was defined as the percentage obtained by dividing the density of the processed product by the theoretical density 3.21 g/cm.sup.3 of silicon carbide.

(5) The residual preform was preheated by being fired in air at 650 C. for 1 hour. The preform was set in a mold immediately after the preheating, and an aluminum alloy containing 12 mass % of silicon and 1 mass % of magnesium and molten at 850 C. was input into the mold so as to sufficiently cover the front surface of the preform. Subsequently, pressing was promptly performed with a punch at a pressure of 56 MPa for 14 minutes. After cooling, the aluminum alloy lump containing a silicon carbide composite was taken out from the mold. The silicon carbide composite was further cut out from the lump.

(6) In order to measure the thermal conductivity at the room temperature, a part of the composite was processed into a sample having a length of 25 mm, a width of 25 mm, and a thickness of 1 mm. The thermal conductivity of this sample was measured by a laser flash method and was 252 W/mK. The sample for measuring the coefficient of thermal expansion was cut out from the composite into a predetermined shape, and the coefficient of thermal expansion was measured from room temperature (25 C.) to 150 C. The results are shown in Table 1.

(7) TABLE-US-00001 TABLE 1 Silicon carbide powder quantity (mass %) Al alloy Coefficient 8 m or more Binder Filling composition Thermal of thermal and less than Less than quantity degree (mass %) conductivity expansion 80-800 m 80 m 8 m Binder (mass %) (vol %) Si Mg (W/mK) (ppm/K) Example 1 65 25 10 Colloidal silica 8.9 69.6 12 0.9 252 6.2 Example 2 65 26 9 Colloidal silica 11.6 67.9 12 0.9 231 6.3 Example 3 65 25 10 Colloidal silica 12 67.6 12 0.9 232 6.4 Example 4 65 25 10 Colloidal silica 12 66.9 12 1.2 233 6.3 Example 5 65 25 10 Colloidal silica 12 67 12 1.6 251 6.3 Example 6 65 25 10 Colloidal silica 6 69 12 0.9 246 6.4 Example 7 60 30 10 Colloidal silica 12 65 12 0.9 245 6.7 Example 8 75 20 5 Colloidal silica 12 62 12 0.9 251 6.9 Example 9 70 20 10 Colloidal silica 12 62 12 1.6 246 6.9 Example 10 70 20 10 Colloidal silica 12 62 12 2.1 242 6.9 Comparative 55 40 5 Colloidal silica 12 65 12 0.9 200 7.5 Example

Example 2

(8) Weighed were 65 mass % of a silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, 26 mass % of a silicon carbide powder having a particle diameter of 8 m or more and less than 80 m, 9 mass % of a silicon carbide powder having a particle diameter of less than 8 m, 11.6 mass % of colloidal silica (Snowtex O manufactured by Nissan Chemical Industries, Ltd., containing 20 mass % of solid content), and 9 mass % of water, which were mixed to prepare a slurry.

(9) As the silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, NG-F80 manufactured by Pacific Rundum Co., Ltd. was used.

(10) As the silicon carbide powder having a particle diameter of 8 m or more and less than 80 m in an amount of 26 mass % and the silicon carbide powder having a particle diameter of less than 8 m in an amount of 9 mass %, a powder prepared by mixing GC-#500 manufactured by Nanko Abrasives Industry Co., Ltd. and GC-1000F and GMF-4S manufactured by Yakushima Denko Co., Ltd. at a blending ratio of 13.5:16.5:5.0 was used.

(11) A preform and a composite were produced as in Example 1. The results are shown in Table 1.

Example 3

(12) Weighed were 65 mass % of a silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, 25 mass % of a silicon carbide powder having a particle diameter of 8 m or more and less than 80 m, 10 mass % of a silicon carbide powder having a particle diameter of less than 8 m, 12.0 mass % of colloidal silica (Snowtex O manufactured by Nissan Chemical Industries, Ltd., containing 20 mass % of solid content), and 9 mass % of water, which were mixed to prepare a slurry.

(13) As the silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, NG-F80 manufactured by Pacific Rundum Co., Ltd. was used.

(14) As the silicon carbide powder having a particle diameter of 8 m or more and less than 80 m in an amount of 25 mass % and the silicon carbide powder having a particle diameter of less than 8 m in an amount of 10 mass %, a powder prepared by mixing GC-#500 manufactured by Nanko Abrasives Industry Co., Ltd., GC-1000F manufactured by Yakushima Denko Co., Ltd., and GC-#4000 manufactured by Nanko Abrasives Industry Co., Ltd. at a blending ratio of 13.5:16.5:5.0 was used. A preform was produced as in Example 1.

(15) A composite was produced using an aluminum alloy containing 12 mass % of silica and 0.9 mass % of magnesium. The results are shown in Table 1.

Example 4

(16) A preform and a composite were produced as in Example 3 except that an aluminum alloy containing 12 mass % of silicon and 1.2 mass % of magnesium was used. The results are shown in Table 1.

Example 5

(17) A preform and a composite were produced as in Example 3 except that an aluminum alloy containing 12 mass % of silicon and 1.6 mass % of magnesium was used. The results are shown in Table 1.

Example 6

(18) As the silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, NG-F80 manufactured by Pacific Rundum Co., Ltd. was used.

(19) As the silicon carbide powder having a particle diameter of 8 m or more and less than 80 m in an amount of 25 mass % and the silicon carbide powder having a particle diameter of less than 8 m in an amount of 10 mass %, a powder prepared by mixing GC-#500 manufactured by Nanko Abrasives Industry Co., Ltd., GC-1000F manufactured by Yakushima Denko Co., Ltd., and GC-#6000 manufactured by Nanko Abrasives Industry Co., Ltd. at a blending ratio of 13.5:16.5:5.0 was used.

(20) A preform and a composite were produced as in Example 3 except that 6 mass % of colloidal silica (Snowtex O manufactured by Nissan Chemical Industries, Ltd., containing 20 mass % of solid content) was weighed, and a slurry was prepared. The results are shown in Table 1.

Example 7

(21) Weighed were 60 mass % of a silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, 30 mass % of a silicon carbide powder having a particle diameter of 8 m or more and less than 80 m, 10 mass % of a silicon carbide powder having a particle diameter of less than 8 m, 12 mass % of colloidal silica (Snowtex O manufactured by Nissan Chemical Industries, Ltd., containing 20 mass % of solid content), and 9 mass % of water, which were mixed to prepare a slurry.

(22) As the silicon carbide powder having a particle diameter of 80 m or more and 800 m or less in an amount of 60 mass %, the silicon carbide powder having a particle diameter of 8 m or more and less than 80 m in an amount of 30 mass %, and the silicon carbide powder having a particle diameter of less than 8 m in an amount of 10 mass %, a powder prepared by mixing NG-F54 manufactured by Pacific Rundum Co., Ltd., GC-#500 manufactured by Pacific Rundum Co., Ltd., and GC-#3000 manufactured by Pacific Rundum Co., Ltd. at a blending ratio of 60:30:10 was used.

(23) A preform and a composite were produced as in Example 1. The results are shown in Table 1.

Example 8

(24) Weighed were 75 mass % of a silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, 25 mass % of a silicon carbide powder having a particle diameter of 8 m or more and less than 80 m, 5 mass % of a silicon carbide powder having a particle diameter of less than 8 m, 12 mass % of colloidal silica (Snowtex O manufactured by Nissan Chemical Industries, Ltd., containing 20 mass % of solid content), and 9 mass % of water, which were mixed to prepare a slurry.

(25) As the silicon carbide powder having a particle diameter of 80 m or more and 800 m or less in an amount of 75 mass %, the silicon carbide powder having a particle diameter of 8 m or more and less than 80 m in an amount of 20 mass %, and the silicon carbide powder having a particle diameter of less than 8 m in an amount of 5 mass %, a powder prepared by mixing NG-F30 manufactured by Pacific Rundum Co., Ltd., NG-F220 manufactured by Pacific Rundum Co., Ltd., and GC-#2000 manufactured by Pacific Rundum Co., Ltd. at a blending ratio of 60:30:10 was used.

(26) A preform and a composite were produced as in Example 1. The results are shown in Table 1.

Example 9

(27) Weighed were 70 mass % of a silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, 20 mass % of a silicon carbide powder having a particle diameter of 8 m or more and less than 80 m, 10 mass % of a silicon carbide powder having a particle diameter of less than 8 m, 12 mass % of colloidal silica (Snowtex O manufactured by Nissan Chemical Industries, Ltd., containing 20 mass % of solid content), and 9 mass % of water, which were mixed to prepare a slurry.

(28) As the silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, NG-F80 manufactured by Pacific Rundum Co., Ltd. was used.

(29) As the silicon carbide powder having a particle diameter of 8 m or more and less than 80 m in an amount of 20 mass % and the silicon carbide powder having a particle diameter of less than 8 m in an amount of 10 mass %, a powder prepared by mixing GC-#800 manufactured by Pacific Rundum Co., Ltd. and GC-#6000 manufactured by Pacific Rundum Co., Ltd. at a blending ratio of 20:10 was used.

(30) A preform was produced as in Example 1. The aluminum alloy contained 12 mass % of silicon and 1.6 mass % of magnesium.

Example 10

(31) A preform and a composite were produced as in Example 9 except that an aluminum alloy containing 12 mass % of silicon and 2.1 mass % of magnesium was used.

Comparative Example

(32) Weighed were 55 mass % of a silicon carbide powder having a particle diameter of 80 m or more and 800 m or less, 40 mass % of a silicon carbide powder having a particle diameter of 8 m or more and less than 80 m, 5 mass % of a silicon carbide powder having a particle diameter of less than 8 m, 12 mass % of colloidal silica (Snowtex O manufactured by Nissan Chemical Industries, Ltd., containing 20 mass % of solid content), and 12 mass % of water, which were mixed to prepare a slurry. This slurry was poured into a plaster mold and was left to stand and was then demolded and dried to obtain a molded body. This molded body was fired in air at 1000 C. for 4 hours into a preform.

(33) As the silicon carbide powder having a particle diameter of 80 m or more and 800 m or less in an amount of 55 mass %, the silicon carbide powder having a particle diameter of 8 m or more and less than 80 m in an amount of 40 mass %, and the silicon carbide powder having a particle diameter of less than 8 m in an amount of 5 mass %, a powder prepared by mixing NG-F150 manufactured by Pacific Rundum Co., Ltd. and GC-1000F manufactured by Yakushima Denko Co., Ltd. at a blending ratio of 2:1 was used.

(34) As obvious from Table 1, the aluminum-silicon-carbide composites of Examples 1 to 10 according to the present invention each have high thermal conductivity and a low coefficient of thermal expansion. It is also demonstrated that these aluminum-silicon-carbide composites each have low specific gravity.

(35) Thus, the aluminum-silicon-carbide composite according to the present invention is preferred as a heat sink material for a power module because of its high thermal conductivity, can be used as a semiconductor module radiator plate because of its low coefficient of thermal expansion, and is also useful as a mounting material for a moving apparatus, such as a car and a train, because of its low specific gravity.