Method of producing sintered silicon nitride

US5998319A · kind A · utility

Assignee

• SKW Trostberg Aktiengesellschaft · DE

Inventor

• Jochen Hintermayer · Trostberg, DE

Key dates

• Filing date: Jun 10, 1998
• Grant date: Dec 7, 1999
• Expiry date: Jun 10, 2018

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C04B35/584
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

By providing a new method of producing sintered silicon nitride, this invention takes into account the fact that parts made of Si.sub.3 N.sub.4 are often used in temperature ranges below 1200.degree. C. and sometimes even below 500.degree. C. and therefore needn't be designed to withstand temperatures above 1200.degree. C. The sintered silicon nitride for these low-temperature applications is obtained by sintering silicon nitride powder of <2 .mu.m with 5 to 20 wt. % of one or more glass components of the same particle size at temperatures below 1400.degree. C. It is a prerequisite that the glass components used, preferably alkali metal borate glasses with a coefficient of thermal expansion .alpha. which matches that of Si.sub.3 N.sub.4, have a transformation point T.sub.g which is below 750.degree. C., and that the individual glass components have a free enthalpy .DELTA.G which is at least 60% of the free enthalpy of SiO.sub.2. For low-temperature applications, Si.sub.3 N.sub.4 parts manufactured cost-effectively in this way fully satisfy the demands made on them in respect of density, strength and .beta.-phase proportion.