The invention relates to a refractory product comprising zirconium dioxide, a use of zirconium dioxide, a zirconium dioxide, a method for manufacturing a refractory product and a refractory product manufactured by means of said method. The zirconium dioxide is in cubic form and is metastable at room temperature. The zirconium dioxide has a content of calcium, magnesium and yttrium of less than 1% by weight.

Cutting tool for machining by removal of matter from abrasive materials such as a material based on wood particles;

tool characterized in that it is composed of a mounting endowed with at least one machining element, and of which at least the machining edge is composed of a high-homogeneity oxide ceramic platelet composed of Al.sub.2O.sub.3 and ZrO.sub.2, with this platelet being obtained from: a homogeneous Al.sub.2O.sub.3XZrO mixture of Al.sub.2O.sub.3 nano-particles of average size smaller than 1 m, and ZrO.sub.2 nano-particles of tetragonal structure and average size smaller than that of the Al.sub.2O.sub.3 particles, with the ZrO.sub.2 content X being between 5 and 20% in mass of ZrO.sub.2 in relation to the total mass, with the mixture being formed into a plate via the gel-casting process followed by sintering or controlled cold isostatic compression, and with the plate (or platelets resulting from the division of the plate) being mechanically honed to produce the cutting edge.

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.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/mm or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.

Setter plates are fabricated from Li-stuffed garnet materials having the same, or substantially similar, compositions as a garnet Li-stuffed solid electrolyte. The Li-stuffed garnet setter plates, set forth herein, reduce the evaporation of Li during a sintering treatment step and/or reduce the loss of Li caused by diffusion out of the sintering electrolyte. Li-stuffed garnet setter plates, set forth herein, maintain compositional control over the solid electrolyte during sintering when, upon heating, lithium is prone, to diffuse out of the solid electrolyte.

A zirconia sintered body is provided having a color tone equivalent to the color tone guides of various natural teeth and having the same aesthetics as a natural front tooth. The present invention provides a colored translucent zirconia sintered body comprising zirconia containing greater than 4.0 mol % and not greater than 6.5 mol % of yttria, less than 0.25 mol % of erbia, less than 2,000 ppm of iron oxide in terms of Fe.sub.2O.sub.3, less than 0.01 wt. % of cobalt oxide in terms of CoO, and less than 0.1 wt. % of alumina; the zirconia sintered body having a relative density of not less than 99.90%, a total light transmittance of not less than 25% and less than 40% for light having a wavelength of 600 nm at a sample thickness of 1.0 mm, and a strength of not less than 500 MPa.

Provided is a method for manufacturing a sintered body for an electrolyte and an electrolyte for a fuel cell using the same. More particularly, the following disclosure relates to a method for preparing an electrolyte having a firm thin film layer by using a sintered body having controlled sintering characteristics, and application of the electrolyte to a solid oxide fuel cell. It is possible to control the sintering characteristics of a sintered body through a simple method, such as controlling the amounts of crude particles and nanoparticles. In addition, an electrode using the obtained sintered body having controlled sintering characteristics is effective for forming a firm thin film layer. Further, such an electrolyte having a firm thin film layer formed thereon inhibits combustion of fuel with oxygen when it is applied to a fuel cell, and thus shows significantly effective for improving the quality of a cell.

The piezoelectric material of the present invention includes a main component composed of a perovskite-type metal oxide represented by Formula (1), at least one of Mn and Ni, and Mg. The content of Ni is 0 mol or more and 0.05 mol or less based on 1 mol of the perovskite-type metal oxide, and the content of Mn is 0 mol or more and 0.005 mol or less based on 1 mol of the perovskite-type metal oxide, provided that the content of Mn and the content of Ni are not simultaneously 0 mol. The content of Mg is 0.001 mol or more and 0.020 mol or less based on 1 mol of the perovskite-type metal oxide.

Formula (1): (Na.sub.xBa.sub.1-y)(Nb.sub.yTi.sub.1-y)O.sub.3 (where x is 0.83 or more and 0.95 or less, y is 0.85 or more and 0.95 or less, and x/y is 0.95 or more and 1.05 or less).

The piezoelectric material of the present invention includes a main component composed of a perovskite-type metal oxide represented by Formula (1), Zn, and Mg. The content of Zn is 0.005 mol or more and 0.050 mol or less based on 1 mol of the perovskite-type metal oxide, and the content of Mg is 0.001 mol or more and 0.020 mol or less based on 1 mol of the perovskite-type metal oxide.

Formula (1): (Na.sub.xBa.sub.1-y)(Nb.sub.yTi.sub.1-y)O.sub.3 (where x is 0.83 or more and 0.95 or less, y is 0.85 or more and 0.95 or less, and x/y is 0.95 or more and 1.05 or less).

The present invention provides a piezoelectric material not containing lead and potassium, showing satisfactory insulation and piezoelectricity, and having a high Curie temperature. The invention relates to a piezoelectric material includes a main component containing a perovskite-type metal oxide represented by Formula (1): (Na.sub.xBa.sub.1-y)(Nb.sub.yTi.sub.1-y)O.sub.3 (wherein, 0.80?x?0.94 and 0.83?y?0.94), and an additive component containing at least one element selected from Mn and Ni, wherein the content of the Ni is 0 mol or more and 0.05 mol or less based on 1 mol of the perovskite-type metal oxide, and the content of the Mn is 0 mol or more and 0.005 mol or less based on 1 mol of the perovskite-type metal oxide.