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:
Feb. 23, 1993
Filed:
Oct. 07, 1991
Marcellus Peuckert, Hofheim am Taunus, DE;
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
A process for the preparation of an Si.sub.3 N.sub.4 ceramic of high strength, wherein .alpha.-Si.sub.3 N.sub.4 powder is mixed with small amounts of at least one of the elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Y in form of an oxide or oxide precursor, the mixture is shaped to a shaped body and the shaped body is sintered under pressures of 1-100 bar in a nitrogen atmosphere at temperatures of 1,750.degree.-2,000.degree. C. is described. The sintered body is heated at temperatures of 1200.degree.-1500.degree. C. in an inert gas atmosphere for at least 10 hours and then cooled. During this procedure, crystalline apatites of the formula A.sub.4+x (SiO.sub.4).sub.3 N.sub.x, A denoting the element added in the form of the oxide or oxide precursor and x denoting a number which is greater than zero and not more than 1.