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.

A hard coating having a composition represented by (Al.sub.xTi.sub.yM.sub.z).sub.aN.sub.(1-a-b)O.sub.b, wherein M is at least one element of Cr and Nb, and x, y, z, a and b are numbers meeting by atomic ratio 0.6x0.8, 0.05y0.38, 0.02z0.2, x+y+z=1, 0.2a0.8, and 0.02b0.10, respectively, having M-O bonds without AlO bonds exceeding an inevitable impurity level as a bonding state identified by X-ray photoelectron spectroscopy, and having only an NaCl-type structure in its X-ray diffraction pattern.

To provide a sintered material having excellent oxidation resistance, as well as excellent abrasion resistance and chipping resistance. A sintered material containing a first compound formed of Ti, Al, Si, O, and N is provided.

The invention concerns a batch for the production of a refractory product, a process for the production of a refractory product, a refractory product as well as the use of a refractory product.

Problem: To provide a cutting tool formed from a silicon nitride-based sintered body having high fracture resistance and having residual stress of a rake face and a flank face in an appropriate range. Solution: A cutting tool (1) formed from a silicon nitride-based sintered body containing not less than 50 volume % silicon nitride-based phase and from 10 to 30 volume % titanium nitride phase, uses an intersection ridge portion of a rake face (2) and a flank face (3) as a cutting edge (4), has a residual stress applied to the titanium nitride phase that is tensile stress, and is such that the tensile stress applied to the titanium nitride phase in the rake face (2) is greater than the tensile stress applied to the titanium nitride phase in the flank face (3).

A sintered material includes a first material and a second material, the first material being partially stabilized ZrO.sub.2 having a crystal grain boundary or crystal grain in which 5 to 90 volume % of Al.sub.2O.sub.3 is dispersed with respect to a whole of the first material, the second material including at least one of SiAlON, silicon nitride and titanium nitride, the sintered material including 1 to 50 volume % of the first material.

To provide a sintered material having excellent oxidation resistance, as well as excellent abrasion resistance and chipping resistance. A sintered material containing a first compound formed of Ti, Al, Si, O, and N is provided.

A CaSiAlON ceramic with enhanced mechanical properties and a method employing micron-sized and submicron precursors to form the CaSiAlON ceramic. The CaSiAlON ceramic comprises not more than 42 wt % silicon, relative to the total weight of the CaSiAlON ceramic. The method employs submicron particles and also allows for substituting a portion of aluminum nitride with aluminum to form the CaSiAlON ceramic with enhanced mechanical properties.

A CaSiAlON ceramic with enhanced mechanical properties and a method employing micron-sized and submicron precursors to form the CaSiAlON ceramic. The CaSiAlON ceramic comprises not more than 42 wt % silicon, relative to the total weight of the CaSiAlON ceramic. The method employs submicron particles and also allows for substituting a portion of aluminum nitride with aluminum to form the CaSiAlON ceramic with enhanced mechanical properties.

A mullite-containing sintered body according to the present invention contains mullite and at least one selected from the group consisting of silicon nitride, silicon oxynitride, and sialon. It is preferable that the mullite-containing sintered body have a thermal expansion coefficient of less than 4.3 ppm/ C. at 40 C. to 400 C., an open porosity of 0.5% or less, and an average grain size of 1.5 m or less.