Abstract: The present invention relates to a zirconia-based sintered body comprising TiN, TiO.sub.2 and ZrO.sub.2 and having electric conductivity and a process for the production thereof. The present invention provides a zirconia-based sintered body which has, at normal temperature, a mechanical strength of not less than 50 kg/mm.sup.2, a fracture toughness of not less than 4 MPam.sup.1/2, a Vickers hardness of not less than 1,000 kg/mm.sup.2 and a volume resistivity of not more than 1 .OMEGA.cm, and which is sinterable under normal pressure at low temperature, and a process for the production thereof.

Abstract: The invention relates to a method for producing a sintered silicon carbide article having a sintered density of at least 90% of the theoretical density and a mechanical flexural strength of 50 kg/mm.sup.2 or higher. This is achieved by adding to a finely divided .alpha.-type silicon carbide powder, a tar pitch in such amounts as to provide 4.2-6 parts by weight of carbon after carbonization and a boron compound such as to correspond to a boron content of 0.005-0.15 parts by weight as densification aids, mixing and shaping the resulting mixture, and then sintering the thus-shaped article in an inert atmosphere at a temperature of from 1950 .degree. to 2300.degree. C.

Abstract: A method for producing high-density sintered silicon carbide articles useful as wear-resistant materials, corrosion-resistant materials and high-temperature structural materials which comprises mixing powdery silicon carbide composed mainly of .alpha.-phase silicon carbide, a boron compound of from about 0.05 to about 0.15 wt. %, as converted to boron, based thereon and a carbonizable organic substance so that the total of combinable carbon content of the powdery silicon carbide and combinable carbon content of the carbonizable organic substance is from about 4 to about 8 wt. %, molding the resulting mixture, and subjecting the molded product to heating at a temperature of from about 1,000.degree. C. to about 2,000.degree. C. in a vacuum and then sintering at a temperature of about 2,300.degree. C. or less in an inert atmosphere to obtain a sintered silicon carbide article having a sintered density of about 90% or more of the theoretical density.

Abstract: A method for producing wear-resistant sintered silicon carbide products as provided herein in which 90 to 50 wt. % of .beta.-SiC having an average particle diameter of not more than one micron is mixed with 10 to 50 wt. % of .alpha.-SiC having an average particle size which is not more than one micron but not less than 1.15 times as large as that of the .beta.-SiC, and wherein tar pitch and a boron compound are added as densification aids to the powdery SiC mixture; the amount of the tar pitch being present in an amount necessary to provide the total carbon content of the powdery SiC mixture, and in a range of 4 wt. % to less than 8 wt. %; and wherein the boron compound is present in an amount of 0.03 wt. % to less than 0.15 wt. % as boron, based upon the powdery SiC mixture and wherein the resulting mixture is molded and sintered at a temperature of from 2050.degree. to 2300.degree. C. in an inert atmosphere.

Abstract: The present invention relates to a method for manufacturing a high-strength sintered silicon carbide article and more particularly, to a method for a sintered silicon carbide article having high mechanical strength by mixing a finely divided silicon carbide powder with the definite amounts of a specific carbon-containing material, a boron compound and silicon powder as densification aids, shaping and then sintering said shaped article under an inert atmosphere.

Abstract: A hollow catalyst carrier and hollow catalyst made of a transition-alumina (e.g. .gamma.-alumina) which comprises a calcined product having a pipe-like or multi-cell structure and having a very large void ratio (i.e. not less than 3%), a very large specific surface area (i.e. not less than 5 m.sup.2 /g), a bulk density of 0.8 to 1.8 g/cm.sup.3, a compressive strength in the extrusion direction of not less than 20 kg/cm.sup.2 and at least one hole in the extrusion direction, and a process for the production thereof by subjecting a powder containing a rehydratable alumina to an extrusion molding, rehydrating the molded product and followed by calcining. The hollow catalyst carrier and hollow catalyst have excellent properties for carrying the catalytically active components thereon and have an excellent mechanical strength.