Abstract: The production of SiC whiskers and of mats thereof on a substrate by treatment, at 1250.degree. to 1500.degree. C., of a gaseous mixture including hydrogen and sources of Si and C atoms which are in the form of at least one oxygen-free compound, in the presence of a metal type catalyst, by a semi-continuous or periodic process, is characterized in that, during the growth period, an Al-Fe catalyst is introduced into the gas phase in the reaction zone, by means of carbon reduction of aluminosilicate ceramics, which comprise at least 73 weight % of Al.sub.2 O.sub.3 and 0.3 to 3.0 weight % of iron oxides and the substrate is a carbonized rayon fiber based carbon fabric which has been pre-treated, prior to carbonization, with a solution of borax and a solution of diammonium phosphate until the quantities of boron and phosphorus in the fabric do not amount to more than 4 and 2 weight %, respectively.

Abstract: A process for making light, fibrous heat insulating materials wherein the silica fibers used in the process are quartz fibers formed by spraying quartz. The fibers are predispersed in water until there is formed a homogeneous flowing slurry from which is molded a green fibrous block, with simultaneous partial removal of water. This green fibrous block is dispersed in water and mixed with an aqueous emulsion containing an organosilicon binder, a boron-containing sintering adjuvant and a surface-active agent. A green billet is molded from the suspension thus obtained, a portion of the water being simultaneously removed by suction. The green billet is compressed until the desired height is obtained and then it is dried, in the compressed state, at a temperature of up to 300.degree. C. The billet is released from pressure and fired at high temperature.

Abstract: A process for manufacturing a heat insulating material including alumina based fibers and aluminosilicate binder. The process includes the steps of: (a) milling alumina based fibers, having a mean diameter less than or equal to 2 .mu.m, in water until a mean aspect ratio (l/d) of 30 to 130 is obtained; (b) vacuum molding a billet from the resulting aqueous, fibrous, flowing slurry; (c) fixing the billet in a frame, while compressing it slightly; (d) drying the slightly compressed billet in the frame to form a dried billet; (e) preparing an aluminosilicate binder having low durability; (f) impregnating the dried billet, fixed in the frame, with the binder; (g) gelling the binder to produce a semi-finished product; (h) removing the semi-finished product from the frame; (i) drying the semi-finished product; and (j) firing the semi-finished product.