Abstract: A ceramics green sheet which is suitably used for producing sintered ceramics substrates and the like is disclosed. The ceramics green sheet according to the present invention includes a ceramics powder, a photoinitiator, a UV absorber such as photoinitiation inhibitor organic dyes and inorganic powders, and a photosensitive resin composition. The ceramics green sheet according to the present invention has an advantage that via holes and through holes may be very easily formed with high precision, and fine holes may be formed reliably and inexpensively.

Abstract: A sintered zirconia material containing at least 50 mol % tetragonal zirconia and 1.5-5 mol % yttria, from which carbon is substantially absent, the porosity of which is not greater than 0.6%, the pore size of which is not greater than 0.1 .mu.m and the pores of which exist mainly at triple points of zirconia grain boundaries. The sintered zirconia material can be obtained by sintering the raw material zirconia powder, the green body or the presintered material containing tetragonal zirconia and yttria in a required amount and in an oxidizing atmosphere, by hot isostatic pressing.The sintered material thus obtained has a high strength and high toughness, and particularly excellent properties for use under conditions of higher than 600.degree. C. and can be used as a material of various industrial machines or tools.

Abstract: A composite element comprises a matrix composed of at least one member selected from the group consisting of oxides, carbides, nitrides and borides and a fibrous material made of at least one member selected from the group consisting of carbon, graphite, oxides, carbides, nitrides and borides. A plurality of composite elements are used as the electrode wall or insulating wall constituting an MHD power generating channel.