Method for producing composite sintered body of silicon carbide and silicon nitride

• US 5,785,922 A
• Filed: 11/16/1995
• Issued: 07/28/1998
• Est. Priority Date: 11/21/1994
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Higuchi, Yoshikatsu, Miyake, Kazumi
• Primary Examiner(s): DERRINGTON, JAMES H
• Application Number:
  US08/559,001
• Time in Patent Office: 985 Days
• Field of Search: 264/65, 264/682, 264/683, 264/668, 501/92, 501/89, 501/90
• US Class Current: 264/682
• CPC Class Codes: C04B 35/575 obtained by pressure sintering
• CPC Class Codes: C04B 35/5755 obtained by gas pressure sintering
• CPC Class Codes: C04B 35/593 obtained by pressure sintering
• CPC Class Codes: C04B 35/5935 obtained by gas pressure sintering

Abstract

A composite sintered body of silicon carbide and silicon nitride having a nano-composite structure in which fine SiC particles are dispersed in Si₃ N₄ particles and grain boundaries and fine Si₃ N₄ particles are dispersed in SiC particles is produced by (a) adding at least one sintering aid, boron and carbon to a mixed powder of silicon carbide and silicon nitride to form a green body, the sintering aid being (i) Al₂ O₃ or AlN and/or (ii) at least one oxide of an element selected from Groups 3A and 4A of the Periodic Table, and (b) sintering the green body by HIP or by a high-temperature normal sintering method.

Claims

1. A method for producing a composite sintered body of silicon carbide and silicon nitride, comprising the steps of:

(a) adding sintering aid powder, boron powder and carbon powder to a mixture of 15-50 weight % of silicon carbide powder and 85-50 weight % of silicon nitride powder to form a green body, said sintering aid powder being a mixture of (i) aluminum oxide or aluminum nitride, and (ii) at least one oxide of an element selected from the group consisting of Y₂ O₃, Yb₂ O₃, Er₂ O₃, ZrO₂ and HfO₂, with a weight ratio of said (i) to said (ii) being from 2;

1 to 1;

15, and

(b) subjecting said green body to a HIP sintering at an atmosphere gas pressure of 1033-2000 kgf/cm².

2. The method for producing a composite sintered body of silicon carbide and silicon nitride according to claim 1, wherein the amount of said sintering aid powder is 15 weight % or less, and the total amount of said boron powder and carbon powder is 0.3-5 weight %, based on the total amount (100 weight %) of said silicon carbide powder and said silicon nitride powder.

3. The method for producing a composite sintered body of silicon carbide and silicon nitride according to claim 1 or 2, wherein the HIP sintering is conducted at a temperature of 1700°

C. or higher.

4. A method for producing a composite sintered body of silicon carbide and silicon nitride, comprising the steps of:

(a) adding at least one sintering aid powder, boron powder and carbon powder to a mixture of 5-50 weight % of silicon carbide powder and 85-50 weight % of silicon nitride powder to form a green body, said sintering aid powder being a mixture of (i) aluminum oxide or aluminum nitride, and (ii) at least one oxide of an element selected from the group consisting of Y₂ O₃, Yb₂ O₃, Er₂ O₃, ZrO₂ and HfO₂, with a weight ratio of said (i) to said (ii) being from 2;

1 to 1;

15, and

(b) subjecting said green body to a gas pressure sintering at a temperature of 2000°

C. or higher and an atmosphere gas pressure of 9-50 kgf/cm².

5. The method for producing a composite sintered body of silicon carbide and silicon nitride according to claim 4, wherein the amount of said sintering aid powder is 15 weight % or less, and the total amount of said boron powder and carbon powder is 0.3-5 weight %, based on the total amount (100 weight %) of said silicon carbide powder and said silicon nitride powder.