Abstract: Mechanically strong and reduced friction porous silicon carbide sintered shaped articles, well adapted for the production, e.g., of leaktight mechanical packings and rotating bearing seals, have a total pore volume ranging from 4% to 18% thereof, the pores of which having an average diameter of the spherical closed pores ranging from 40 to 200 .mu.m.

Abstract: Composite shaped articles, well adapted for aerospace applications, include a vitreous matrix and an effective amount of a reinforcing agent therefor, preferably a fibrous and ceramic reinforcing agent, such vitreous matrix being based on silica, alumina, zirconia, an alkali metal oxide and an alkaline earth metal oxide, in the following proportions by weight relative to the total weight of the matrix:______________________________________ (1) 50% .ltoreq. SiO.sub.2 .ltoreq. 80% (2) 7% .ltoreq. Al.sub.2 O.sub.3 .ltoreq. 20% (3) 2% .ltoreq. ZrO.sub.2 .ltoreq. 10% (4) 2% .ltoreq. .SIGMA.A.sub.2 O .ltoreq. 7% (5) 4% .ltoreq. .SIGMA.BO .ltoreq. 10% ______________________________________wherein .SIGMA.A.sub.2 O and .SIGMA.BO represent the respective total amounts by weight of the alkali metal oxides and the alkaline earth metal oxides present in said matrix.

Abstract: Glass compositions containing oxygen and nitrogen prepared by melting admixture of magnesia and/or a magnesium silicate, silica and an aluminum nitride produced by reacting ammonia with aluminum oxide, have the formula:Mg.sub.x Si.sub.y Al O.sub.u N.sub.v (1)in which 0.25.ltoreq.x.ltoreq.2.50, 1.25.ltoreq.y.ltoreq.3.50, 3.75.ltoreq.u.ltoreq.10.50, and 0.05.ltoreq.v.ltoreq.0.75, with the proviso that 2x+4y+3=2u+3v; the subject glass compositions are thermally converted into vitroceramics having the same formula and including a single cordierite crystalline phase, which vitroceramics are well adapted for the production of composite shaped articles.

Abstract: Composite shaped articles, well adapted for aerospace applications, include a glass-ceramic and an effective amount of a reinforcing agent therefor, preferably a fibrous and ceramic reinforcing agent, such glass-ceramic matrix being based on silica, alumina, an alkaline earth metal oxide and a rare earth oxide, in the following proportions by weight relative to the total weight of the matrix:5%.ltoreq.MO.ltoreq.40%25%.ltoreq.SiO.sub.2 .ltoreq.70%15%.ltoreq.Al.sub.2 O.sub.3 .ltoreq.70%5%.ltoreq.rare earth oxide.ltoreq.70%wherein M represents an alkaline earth metal.

Abstract: Shaped, porous filter members having a size and shape adapted for the filtration of liquid metals, e.g., the configuration of a honeycomb, are comprised of a porous alveolar ceramic material including from 10 to 20% SiO.sub.2, from 50 to 60% Al.sub.2 O.sub.3 and from 20 to 40% ZrO.sub.2, each percentage being by weight with respect to the total weight of said oxides, said Al.sub.2 O.sub.3 and SiO.sub.2 being present in the form of mullite, 3Al.sub.2 O.sub.3 /2SiO.sub.2, and the combined weight of the zirconia and mullite comprising at least 90% by weight of said alveolar ceramic material.