Abstract: A body including a first phase having silicon carbide, a second phase comprising a metal oxide, the second phase being a discrete intergranular phase located at the grain boundaries of the first phase, and the body has an average strength of at least 700 MPa.

Abstract: The invention relates to a process for fabrication of a porous refractory ceramic product made from SiC, by heat treatment and sintering at high temperature, starting from a fraction of fine particles of SiC and from a fraction of larger-sized particles of SiC, said process being characterized in that, in a step preliminary to the heat treatment and to the sintering at high temperature, the finest particles of SiC are agglomerated then, in a second step, the granules thus obtained are added to the SiC powder with particles of larger size. The invention also relates to a porous body made from recrystallized SiC in an essentially ? form, in particular a particulate filter for automobile application, obtained by such a process.

Abstract: The invention relates to a process for fabrication of a porous refractory ceramic product made from SiC, by heat treatment and sintering at high temperature, starting from a fraction of fine particles of SiC and from a fraction of larger-sized particles of SiC, said process being characterized in that, in a step preliminary to the heat treatment and to the sintering at high temperature, the finest particles of SiC are agglomerated then, in a second step, the granules thus obtained are added to the SiC powder with particles of larger size. The invention also relates to a porous body made from recrystallized SiC in an essentially ? form, in particular a particulate filter for automobile application, obtained by such a process.

Abstract: An improved process of preparing silicon nitride by the direct nitridation of silicon metal is disclosed. The process is a multi-step one which is substantially more efficient than prior processes and produces a silicon nitride having an oxygen content of less than 1%, a silicon metal content of less than 0.5%, and an alpha phase content of at least 85%, preferably at least 90%. The silicon nitride may be converted to a powder.

Abstract: Very tough composites of silicon carbide fibers in silicon nitride matrices, especially reaction bonded silicon nitride matrices, can be made by precoating the fibers with pyrolytic carbon and controlling the nitridation or other process which forms the silicon nitride matrix so that a thickness of at least 5 nanometers of carbon remains in the composite after it is formed. Failure of such composites is non-catastrophic.

Abstract: A chromia-magnesia based refractory product made up of fused chromia-magnesia grains bonded by an in situ formed chromia-magnesia bond. The product is very dense and especially suitable when used to process molten materials which involve coal slag.

Abstract: A lightweight insulating refractory shape is made of Si.sub.2 ON.sub.2 having a density of less than 50% of theoretical, a relatively high compressive strength, a low thermal conductivity and high resistance to attack by chlorine, fused chlorides and molten aluminum.