Abstract: Spinel single crystal filaments are produced by a method which consists essentially of solidifying in one direction a melt consisting essentially of 30 to 70% by weight of magnesium oxide, 10 to 45% by weight of aluminum oxide, and 15 to 45% by weight of silicon dioxide, thereby forming a composite texture containing a matrix of forsterite and filaments of spinel dispersed in the matrix, and then separating the filaments of spinel from the composite texture.

Abstract: A sintered silicon oxynitride composition comprises as an amount of starting material the combination of (a) a silicon component comprising silicon nitride(Si.sub.3 N.sub.4) and silicon oxide(SiO.sub.2) in a mol ratio of SiO.sub.2 /Si.sub.3 N.sub.4 being 0.7 to 1.2, and (b) at least one second component selected from an aluminum oxide, an aluminum nitride, a rare earth oxide, and a rare earth nitride, said second component being in an amount of from about 0.1 to 10 mol per 100 mol of said silicon component.

Abstract: An alumina silica sintered ceramic that is produced by the normal sintering method and which has bending strength of at least 300 MPa at room temperature and at least 400 MPa at an elevated temperature, for example, 1,300.degree. C. is disclosed.This sintered ceramic is produced by a process comprising the following steps: providing a chiefly amorphous starting powder that consists of 62-73 wt % Al.sub.2 O.sub.3 and correspondingly 38-27 wt % SiO.sub.2 ; calcining this starting powder to make a calcined product that is chiefly composed of a crystalline phase and which contains oxides of an alkali metal and an alkaline earth metal in a total amount of no more than 1,500 ppm; pressing the ground particles of the calcined product into a compact; and sintering the compact at 1,500.degree.-1,750.degree. C. and at atmospheric pressure.

Abstract: A high-strength sintered article of chemical substances having the .beta.-silicon nitride type crystal structure is produced by blending 50 to 99.9 weight percent of a .beta.-silicon nitride and/or .beta.'-Sialon and 50 to 0.1 weight percent of a mixture, as a sintering aid, consisting of BeO, Ga.sub.2 O.sub.3, and Al.sub.2 O.sub.3 in respective amounts such as to have a Ga.sub.2 O.sub.3 /BeO ratio in the range of from 2.8 to 9.4, an Al.sub.2 O.sub.3 /BeO ratio in the range of from 0.0 to 2.6, and an Al.sub.2 O.sub.3 /Ga.sub.2 O.sub.3 ratio in the range of from 0.0 to 1.1, all ratios being ratios by weight and sintering the resultant blend.