Abstract: There is provided an electric heater support plate which is not likely to be softened or deformed during firing at a high temperature, even if a material to be fired contains an alkaline component or an Si component as a volatile component. A passage 2 for the material to be fired surrounded by a ceiling refractory 11, wall refractories 12 and a floor refractory 13 is provided with an electric heater 3 heating from above and an electric heater 5 heating from below. This electric heater 3 has at least its heating part 31 mounted and supported on a fire-resistant support plate 4, and this support plate 4 in this invention has a two-layer structure in which an insulating ceramic support plate 41 is laminated on an SiC-based ceramic plate 42.

Abstract: A material with a low volume resistivity at room temperature composed of an aluminum nitride sintered body is provided. The sintered body contains samarium in a converted content calculated as samarium oxide of not lower than 0.04 mole percent. The sintered body contains an aluminum nitride phase and a samarium-aluminum complex oxide phase. The samarium-aluminum complex oxide phase forms intergranular layers with a low resistivity along the intergranular phase between aluminum nitride grains.

Abstract: A material with a low volume resistivity at room temperature composed of an aluminum nitride sintered body is provided. The sintered body contains samarium in a converted content calculated as samarium oxide of not lower than 0.04 mole percent, and the sintered body contains aluminum nitride phase and samarium-aluminum complex oxide phase. The samarium-aluminum complex oxide phase forms intergranular layers with a low resistivity along the intergranular phase between aluminum nitride grains.

Abstract: An apparatus for testing a tube for its strength to resist internal pressure, is composed of: an expandable elastomer having a hollow body with one open end; a test head, connected to the expandable elastomer, to provide the expandable elastomer with pressure using fluid as a medium; a holder, disposed below the test head, to vertically move a tube into a place in which the expandable elastomer is inserted into a tube; and a transferring mechanism, arranged beside the holder, to provide the holder with a tube from a rack. The apparatus according to the present invention can automatically and continuously test numerous tubes for its strength to resist internal pressure, overcoming disadvantages of the non-automatic, non-continuous apparatus previously disclosed.