Patent ID: 7275397
Filing Date: 2007-10-02
Classification: C03B,C04B

Abstract:
1. A high-temperature molding method for the production of a silica article having near net-shape, comprising the following steps: (A) providing a high temperature free-flow mold for the production of near net-shape silica article, comprising a detachable upper part placed over a lower part, wherein (i) the upper part has an inner surface and an outer surface and an edge portion; (ii) the lower part has a first surface and a second surface and an edge portion; (iii) at least one of (a) the inner surface of the upper part and (b) the second surface of the lower part is dome-shaped; (iv) the upper part and the lower part are engaged at the edge portions, such that the inner surface of the upper part and the first surface of the lower part define a mold cavity having the shape of the near net-shape article to be manufactured; (v) the upper part has an opening that allows the introduction of silica bulk material into the mold cavity; (B) placing the mold in a way such that the upper part is located over the lower part; (C) placing silica bulk into the mold via the opening in the upper part; (D) heating the mold and the bulk silica to a flow temperature in an inert atmosphere such that the silica bulk reaches a viscosity and flows to fill the mold cavity; (E) cooling the mold assembly and the silica bulk; (F) detaching the upper part and the lower part of the mold from the cast silica bulk at a temperature below the glass transition temperature of silica; (G) annealing the cast silica bulk to form the near net-shape silica article.