An alumina/titanium silicon carbide composite material is prepared by making titanium aluminum carbide (Ti.sub.3AlC.sub.2) in uniform contact with silicon monoxide (SiO), and carrying out vacuum sintering. The composite material is obtained through mutual diffusion of aluminum and silicon and has high compactness and stable performance. In the composite material, the alumina is generated by means of a reaction between the titanium aluminum carbide and the silicon monoxide, and can be uniformly wrapped around surfaces of titanium silicon carbide crystals to form a relatively compact oxide film, such that substance exchange between a matrix and the outside is hindered, and overall antioxidation of the composite material is improved. Toughness of the composite material is enhanced by means of the titanium silicon carbide. The prepared composite material has relatively high purity, relatively low sintering temperature, and relatively high bending strength. The process is simple and convenient for industrial production.

A cBN sinter comprising cubic boron nitride grains and a binder phase, the binder phase comprising Ti.sub.2CN and TiAl.sub.3, wherein the ratio I.sub.Ti2CN/I.sub.TiAl3 of the peak intensity I.sub.Ti2CN of Ti.sub.2CN appearing at 2θ=41.9° to 42.2° to the peak intensity I.sub.TiAl3 of TiAl.sub.3 appearing at 2θ=39.0° to 39.3° is in a range of 2.0 to 30.0 in an XRD measurement.

A composite polycrystal contains polycrystalline diamond formed of diamond grains that are directly bonded mutually, and non-diamond carbon dispersed in the polycrystalline diamond, and has a concentration of contained hydrogen of less than or equal to 1000 ppm.

A composite polycrystal contains polycrystalline diamond formed of diamond grains that are directly bonded mutually, and non-diamond carbon dispersed in the polycrystalline diamond, and has a concentration of contained hydrogen of greater than 1000 ppm and less than or equal to 20000 ppm.

In one aspect, sintered ceramic bodies are described herein which, in some embodiments, demonstrate improved resistance to wear and enhanced cutting lifetimes. For example, a sintered ceramic body comprises tungsten carbide (WC) in an amount of 40-95 weight percent, alumina in an amount of 5-30 weight percent and ditungsten carbide (W.sub.2C) in an amount of at least 1 weight percent.

Disclosed is a ceramic sintered shaped body containing Y.sub.2O.sub.3-stabilized zirconia with a sintered density of at least 99% of the theoretical sintered density and having a mean grain size of <180 nm. The zirconia fraction of the sintered shaped body comprises tetragonal and cubic phases. Also disclosed is a process for the production of a ceramic sintered shaped body containing Y.sub.2O.sub.3-stabilized zirconia, which process comprises dispersion of a submicron powder and comminution of the dispersed submicron powder by means of grinding media having a diameter of less than or equal to 100 μm to a particle size d.sub.95 of <0.42 μm; shaping of the dispersion to form a body, and sintering of the body to form the sintered shaped body.

A thermistor material and a method for preparing a thermistor material are provided. The thermistor material is prepared by mixing and heating a mixture containing BaTiO.sub.3, B.sub.2O.sub.3, SiO.sub.2, Li.sub.2O, P.sub.2O.sub.5, Cs.sub.2O, Nd.sub.2O.sub.3, Al.sub.2O.sub.3 and TiO.sub.2.

A method of making polycrystalline diamond material includes providing a fraction of diamond particles or grains and a sintering additive, the sintering additive comprising a carbon source of nano-sized particles or grains, forming the diamond particles and sintering additive into an aggregated mass, consolidating the aggregated mass and a binder material to form a green body, and subjecting the green body to conditions of pressure and temperature at which diamond is more thermodynamically stable than graphite and for a time sufficient to consume the sintering additive, sintering it and forming polycrystalline diamond material that is thermodynamically and crystallographically stable and is substantially devoid of any nano-structures.

A sintered material is provided having a phase of a compound at least containing a rare earth element and fluorine, the sintered material having an L* value of 70 or more in the L*a*b* color space. The crystal grains of the sintered material preferably has an average grain size of 10 μm or less. The sintered material preferably has a relative density of 95% or more. The sintered material preferably has a three-point flexural strength of 100 MPa or more. The sintered material preferably contains no oxygen, or preferably has an oxygen content of 13% by mass or less when containing oxygen. The compound is preferably rare earth element fluoride or oxyfluoride.

A composite material having a first phase includes an aluminum oxide proportion of at least 65% by volume and a second phase comprising a zirconium proportion of 10 to 35% by volume. The zirconium is present as zirconium oxide. The aluminum oxide is a ceramic matrix and the zirconium oxide is dispersed therein. From 90 to 99% of the zirconium oxide is present in the tetragonal phase. A chemical stabilizer for stabilizing the tetragonal phase of the zirconium oxide is also present. The total content of chemical stabilizer is <0.2 mol % relative to the zirconium oxide content.