Process for producing densely sintered silicon nitride components

US5656219A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Gunter Riedel · Kelkheim, DE
• Hartmut Kruner · Eppstein, DE
• Cornelia Boberski · Hofheim, DE
• Friedrich Hessel · Mainz, DE
• Wolfgang Bocker · Eppstein, DE
• Jurgen Heinrich · Selb, DE
• Matthias Steiner · Seiersberg, AT
• Petra Dotsch · Selb, DE
• Ottmar Rosenfelder · Selb, DE

Key dates

• Filing date: Sep 21, 1995
• Grant date: Aug 12, 1997
• Expiry date: Sep 21, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C04B35/5935
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

In the process for producing a homogeneous and finely crystalline silicon nitride ceramic, ceramic powder is milled, mixed with shaping aids, the mixture is shaped into parts and the shaped parts are subsequently sintered in a nitrogen atmosphere. According to the invention, sintering is carried out in a multistage process at temperatures T.sub.max in the range from 1700.degree. to 1900.degree. C. using gas pressures in the range from 0.3 to 50 MPa. In a first temperature stage, a temperature from 0.9 to 0.96.multidot.T.sub.max is maintained over a time period from 10 to 50 minutes at an N.sub.2 pressure from 0.2 to 1.2 MPa, while in a second temperature stage a temperature from 0.97 to 0.985.multidot.T.sub.max is maintained over a time period from 20 to 80 minutes at an N.sub.2 pressure from 3 to 6 MPa. Then the temperature is increased to T.sub.max and the pressure is increased to from 7 to 50 MPa.