The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 07, 1992
Filed:
Nov. 27, 1989
Marcellus Peuckert, Hofheim am Taunus, DE;
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
The invention relates to a silicon nitride ceramic having a high strength both at low temperatures and at temperatures above 1000.degree. C., and to a process for its preparation. The silicon nitride ceramic contains, as the primary phase, .beta.-silicon nitride and, as a crystalline secondary phase, an yttrium compound which has been caused to crystallize out from the intergranular glass phase by thermal after-treatment. Teh yttrium-containing, crystalline secondary phase has the following d-values in an X-ray diffraction pattern using Cu-K.alpha. radiation: 4.69 .circle.; 4.05 .circle.; 3.48 .circle.; 3.20 .circle.; 3.06 .circle.; 2.81 .circle.; 2.40 .circle.; 2.07 .circle.; 2.03 .circle.; and 1.87 .circle., the most intense diffraction reflection having the d-value 3.06 .circle..+-.0.01 .circle.. A residue of amorphous glass phase is present in the ceramic as a further phase between the crystal grains.