Provided is a zirconia sintered body that uses coloring of cerium oxide, the zirconia sintered body exhibiting a bright red color. The zirconia sintered body includes an oxide of cerium is an amount of 0.5% by mole or more and less than 4% by mole in terms of CeO.sub.2, yttria in an amount of 2% by mole or more and less than 6% by mole, an oxide of aluminum in an amount of 0.1% by weight or more and less than 2% by weight, and the balance being zirconia. The oxide of cerium contains trivalent cerium, and the zirconia has a crystal structure including a tetragonal phase.

Provided are a liquid-crystal-display protection plate that has a high strength, is produced at a reduced cost, and has a shape including a curved surface; and a method for producing the liquid-crystal-display protection plate. The liquid-crystal-display protection plate is formed of a spinel sintered body. The spinel sintered body has an average grain size of 10 m or more and 100 m or less. The liquid-crystal-display protection plate has a shape including a curved surface.

There is provided a lead- and potassium-free piezoelectric material having a high piezoelectric constant and a satisfactory insulation property and a piezoelectric element that includes the piezoelectric material. The piezoelectric material contains a perovskite-type metal oxide having the general formula (1): (Na.sub.xBa.sub.1-y)(Nb.sub.yTi.sub.1-y)O.sub.3 (wherein x satisfies 0.80?x?0.95, and y satisfies 0.85?y?0.95); and at least one rare-earth element selected from La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, wherein the rare-earth element content is more than 0 mol % and 5 mol % or less of the amount of perovskite-type metal oxide. The piezoelectric element includes the piezoelectric material.

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.

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.

A composite material comprising 50 to 95 mass % grains of primary material selected from the group consisting of talc, mica, graphite and hexagonal boron nitride, and 0.01 to 40 mass % fibres having a length of 0.05 to 20 mm, and a ratio of length to diameter of at least 5. The grains of the primary material have a mean size of 3 to 50 microns.

[Problem to be Solved]

Provided are an aluminum-silicon-carbide composite having high thermal conductivity, low thermal expansion, and low specific gravity and a method for producing the composite.

[Solution]

Provided is an aluminum-silicon-carbide composite formed by impregnating a porous silicon carbide molded body with an aluminum alloy. The ratio of silicon carbide in the composite is 60 vol % or more, and the composite contains 60-75 mass % of silicon carbide having a particle diameter of 80 m or more and 800 m or less, 20-30 mass % of silicon carbide having a particle diameter of 8 m or more and less than 80 m, and 5-10 mass % of silicon carbide having a particle diameter of less than 8

Various shaped abrasive particles are disclosed. Each shaped abrasive particle includes a body having at least one major surface and a side surface extending from the major surface.

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.

The present invention provides a focus ring having favorable plasma resistance. In addition, the present invention provides a method for producing a focus ring which enables the easy production of focus rings having favorable plasma resistance. The focus ring of the present invention is a focus ring made of a sintered body of silicon carbide, in which the sintered body includes a plurality of first crystal grains having an -SiC-type crystal structure and a plurality of second crystal grains having a -SiC-type crystal structure, a content of the first crystal grains is 70% by volume or more of a total of the first crystal grains and the second crystal grains, and a volume-average crystallite diameter of the first crystal grains is 10 m or less.