Abstract: The instant invention relates to a novel dental glaze which matures at a temperature of from 1400.degree. to 1600.degree. F, that is, at least 200.degree. lower than the vitrifying temperature of dental porcelain. The chemical composition of this novel glaze may be thusly represented, on a weight basis:______________________________________ SiO.sub.2 45-52% B.sub.2 O.sub.3 15-20% Al.sub.2 O.sub.3 10-15% K.sub.2 O 3.5-7.5% Na.sub.2 O 12-17% CaO 0-1% ZnO 0-1% F 1-3% ______________________________________Preferably the instant novel glaze is further characterized as having an average particle size of 10 .+-. 4 microns and not more than 1% of the particles having a diameter greater than 30 microns.

Abstract: An aqueous slurry comprising an intimate mixture of colloidal silica, (preferably an amorphous, precipitated, hydrated silica), caustic potash, boric acid and alumina is first prepared and then dried. The dried aggregates are thereafter crushed, calcined and rapidly quenched. It is preferred to dry the slurry in a spray drier and thereafter omit crushing after drying and to calcine the dried admixture by means of a plasma arc so that the mixture is rapidly quenched after calcination. The calcined mixture is introduced into a crusher, such as a ball mill, with a carbonaceous cellulating agent and reduced to a fine pulverulent material. The pulverulent material is then cellulated in a cellulating furnace to form cellular borosilicate bodies. Where desired, the calcined material may be utilized as a ceramic frit.

Abstract: A glaze resistor composition composed of magnesium silicide, molybdenum disilicide, tantalum disilicide and glass frit, and if necessary, manganese disilicide and/or aluminum oxide. Due to the use of magnesium silicide, glaze resistors having stable resistivities in a wide resistivity range can be obtained. Due to the use of manganese disilicide, the temperature coefficient of resistivity can be shifted to the positive side, and due to the use of aluminum oxide, the resistivity can be increased and made more stable. This invention also provides a method of making a glaze resistor using two heating steps, in which aluminum oxide is mixed in the starting powder mixture to be subjected to the first heating step, so as to enhance the effect of the aluminum oxide addition.

Abstract: A low mass thixotropic alumina-silica refractory mix for producing kiln furniture having smooth surfaces combined with low weight and consequent low heat capacity.

Abstract: A method of producing a sintered silicon carbide body high in density, flexural strength and purity at elevated temperatures from polycarbosilanes is disclosed. The method involves the following steps:(A) polymerizing organosilicon compounds to yield specific polycarbosilanes which are insoluble in solvents and unmeltable i.e. the polycarbosilanes being higher in melting temperature or in softening temperature than in thermal decomposition temperature;(B) pulverizing the insoluble and unmeltable polycarbosilanes so as to form a powder;(C) applying heat with or without the use of pressure to the powder charged into a hot press mold in a nonoxidizing atmosphere to thereby decompose the same thermally into silicon carbide and sintering the silicon carbide under pressure.