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. 21, 1995
Filed:
Dec. 31, 1992
George C-T. Wei, Weston, MA (US);
John Walsh, Milford, MA (US);
Valenite Inc., Madison Heights, MI (US);
Abstract
A method of making a continuously sintered ceramic body. A ceramic green body is prepared from a powder mixture comprising alumina, TiC (or Ti(C,N)), in a weight ratio of alumina to TiC of about 40:60-95:5, a densification aid, and TiO.sub.2 in a weight ratio of TiO.sub.2 to alumina plus TiC of 0:100 to about 2:98. The green body is prefired, then continuously rapid sintered by heating in a belt furnace in Ar or N.sub.2 containing up to 8 w/o H.sub.2 to about 1800.degree.-1920.degree. C. for a time sufficient to achieve a density of at least about 4.12 g/cc. The rate of travel of the prefired body through the belt furnace provides a heating rate above about 800.degree. C. between about 225.degree. C./min. and the rate at which the body experiences thermal shock. Carbon monoxide is intoduced to the atmosphere during the sintering step only after the 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 in the furnace such that CO is released only above 1400.degree. C. The body may be prepared from a homogeneous slurry, and the green body may be presintered, isopressed, and sintered or sintered and hot-isostatic-pressed.