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:
Aug. 30, 1994
Filed:
Dec. 31, 1992
George C Wei, Weston, MA (US);
John Walsh, Milford, MA (US);
Valenite Inc., Madison Hts., MI (US);
Abstract
A method of making a sintered ceramic body for applications such as wear resistant parts and cutting tools. A green body is prepared from a powder mixture including alumina, TiC or (Ti(C,N)), a densification aid, and TiO.sub.2. The weight ratio of alumina to TiC in the body is about 40:60 to about 95:5; that of TiO.sub.2 to alumina plus TiC is 0:100 to about 2:98. The green body is rapid sintered by heating in a sintering atmosphere to about 1800.degree.-1920.degree. C. for a time sufficient to achieve a density of at least about 4.20 g/cc. The heating rate above about 800.degree. C. is between about 120.degree. C./min and the rate at which the green body experiences thermal shock. The sintering atmosphere is Ar-H.sub.2 or N.sub.2 -H.sub.2 in a molar ratio of Ar or N.sub.2 to H.sub.2 of about 92:8 to 100:0. Carbon monoxide is introduced to the sintering atmosphere only after the sintering temperature exceeds about 1400.degree. C. The amount of CO introduced is selected to inhibit reaction between the alumina and TiC. The CO may be introduced by placing a mass of graphite including adsorbed oxygen and water in the furnace at initiation of sintering such that the mass releases CO only after the sintering temperature exceeds 1400.degree. C. The body may be prepared from a homogeneous slurry, which is dried and shaped to form a green body having a density of at least about 30% of theoretical. The green body may be presintered, isopressed to collapse any cracks, macroscopic pores, or voids, and sintered or sintered and hot-isostatic-pressed.