Abstract: Provided is a heat reflective member, which is prevented from braking even in a high-temperature environment. It generates no dust in use, and can be washed with a chemical liquid. The heat reflective member has a laminated structure in which quartz glass layers are formed on an upper surface and a lower surface of a siliceous sintered powder layer. The heat reflective member includes: an impermeable layer which is formed at a portion of the siliceous sintered powder layer at an end portion of the heat reflective member, which has a thickness at least larger than half of a thickness of the siliceous sintered powder layer, and through which a gas or a liquid is prevented from penetrating; and a buffer layer which is formed between the impermeable layer and the siliceous sintered powder layer, and which changes in density from the impermeable layer toward the sintered powder layer.

Abstract: One aspect is a reflective member, which has a laminated structure in which transparent quartz glass members are formed on an upper surface and a lower surface of an opaque siliceous sintered powder layer. The opaque siliceous sintered powder layer has a thickness of 0.1 mm or more and a thickness distribution of ±0.05 mm or less. When a load is applied to each of the transparent quartz glass members on an upper surface and a lower surface of the laminated structure in a direction parallel to the laminated structure, the reflective member is fractured at a load of 5 N or more per square centimeter. The laminated structure includes a semi-transparent portion having a width of 0.01 mm or less, which has an intermediate opacity between an opacity of the opaque siliceous sintered powder layer and an opacity of each of the transparent quartz glass members.

Abstract: A core drill having a shank and a cup shaped base metal section constructed of a disk shaped top wall and a cylindrical side wall provided on a fore-end of the shank. A grinding stone portion is mounted on an outer end part of the base metal section, with abrasive grains fixed to the outer end part of the base metal section. Abrasive grain layers are formed in a spiral pattern on inner and outer side surfaces of the cylindrical side wall of the base metal section, with abrasive grains fixed to the inner and outer side surfaces of the cylindrical side wall thereof. When the grinding stone portion is put into rotational contact with a workpiece, the workpiece is ground through to form a circle hole in section leaving a cylindrical core therein.

Abstract: The present invention relates to an outer-diameter blade, an inner-diameter blade and cutting machines which respectively use the outer-diameter blade and the inner-diameter blade for cutting hard material, such as metal, ceramics, semiconductor single crystal, glass, quartz crystal, stone, asphalt or concrete, and a core drill and a core-drill processing machine which drives the core drill for forming a hole in the hard material.

Abstract: Provided are an outer-diameter blade, an inner-diameter blade and cutting machines using both blades for cutting hard material, and a core drill and a core-drill processing machine for forming a hole into hard material, whereby the mechanical processing with reduction in the cutting and/or contact resistance to the tools is realized, so that in the case of the outer-diamond blade, it is prevented from occurring that a to-be-cut object is warped and put into contact to the blade to cause chipping; in the case of the inner-diameter blade, it is prevented from occurring that the blade is bowed and/or a cutting surface is curved; and in the case of the core drill, not only are grinding powder of a workpiece and loosed-off abrasive grains effectively removed to prevent those from being loaded between the drill and the workpiece, but neither of cracking and chipping occur when the drill passes through the workpiece.

Abstract: A light-weight base body of a reflecting mirror, such as those used in reflecting astronomical telescopes, is proposed which is made from fused silica glass or high-silica glass and is advantageous in respect of the excellent thermal and mechanical stability in dimensions to ensure high performance of the reflecting mirror. The base body is composed of a front plate, i.e. a surface plate to provide the optical surface, and a supporting body of porous foamed glass integrally bonded to the front plate. These two parts of the base body can be bonded together by sandwiching a layer of a finely divided silica powder therebetween and heating the assemblage at a temperature higher than the softening point of the silica powder so that the silica powder is softened or melted to firmly join the two parts sandwiching the powder layer.

Abstract: A light-weight base body of a reflecting mirror, such as those used in reflecting astronomical telescopes, is proposed which is made from fused silica glass or high-silica glass and is advantageous in respect of the excellent thermal and mechanical stability in dimensions to ensure high performance of the reflecting mirror. The base body is composed of a front plate, i.e. a surface plate to provide the optical surface, and a supporting body of porous foamed glass integrally bonded to the front plate. These two parts of the base body can be bonded together by sandwiching a layer of a finely divided silica powder therebetween and heating the assemblage at a temperature higher than the softening point of the silica powder so that the silica powder is softened or melted to firmly join the two parts sandwiching the powder layer.

Abstract: An improved method is proposed for the preparation of a semiconductor silicon single crystal of N-type by the Czochralski process, which is free from the problem of occurrence of delayed OSFs as defects in the single crystal even after prolonged storage at room temperature based on the discovery that presence of a certain amount of aluminum in the melt of silicon contained in a fused silica glass crucible acts to suppress occurrence of delayed OSFs as a type of defects in the single crystal while copper as an impurity acts adversely in this regard. With a known fact that an about 30 .mu.m thick inner surface layer of the crucible is melted down into the silicon melt during the single crystal pulling-up process, namely, the invention proposes use of a crucible of which the inner surface layer of 30 .mu.m thickness contains aluminum in an average concentration of 40 to 500 ppm by weight while the content of copper is as low as possible not to exceed 0.5 ppb by weight.

Abstract: A light-weight base body of a reflecting mirror, such as those used in reflecting astronomical telescopes, is proposed which is made from fused silica glass or high-silica glass and is advantageous in respect of the excellent thermal and mechanical stability in dimensions to ensure high performance of the reflecting mirror. The base body is composed of a front plate, i.e. a surface plate to provide the optical surface, and a supporting body of porous foamed glass integrally bonded to the front plate. These two parts of the base body can be bonded together by sandwiching a layer of a finely divided silica powder therebetween and heating the assemblage at a temperature higher than the softening point of the silica powder so that the silica powder is softened or melted to firmly join the two parts sandwiching the powder layer.

Abstract: The invention provides a light-weight base body of a reflecting mirror such as a mirror in a reflecting astronomical telescope, which is very stable not only thermally but also mechanically and is highly resistant against adverse environmental influences. The mirror base is composed of a porous foamed disc body of fused quartz glass or high-silica glass sandwiched by two plates of fused quartz glass or high-silica glass, of which one is made from transparent glass and serves to provide an optical surface having flatness or a specified curvature, and the side surface of the porous foamed disc body is protected against environmental influences by providing an air-tight sealing layer formed from a silicone rubber-based sealing agent or a thin sheet of fused quartz glass or high-silica glass.

Abstract: The invention provides a light-weight base body of a reflecting mirror such as a mirror in a reflecting astronomical telescope which is very stable not only thermally but also mechanically and is highly resistant against adverse environmental influences. The mirror base is composed of a porous foamed disc body of fused quartz glass or high-silica glass sandwiched by two plates of fused quartz glass or high-silica glass, of which one is made from transparent glass and serves to provide an optical surface having flatness or a specified curvature, and the side surface of the porous foamed disc body is protected against environmental influences by providing an air-tight sealing layer formed from a silicone rubber-based sealing agent or a thin sheet of fused quartz glass or high-silica glass.

Abstract: The invention provides a method of preparing a light-weight base body of a reflecting mirror such as a mirror in a reflecting astronomical telescope, which is very stable not only thermally but also mechanically and is highly resistant against adverse environmental influences. The mirror base is composed of a porous foamed disc body of fused quartz glass or high-silica glass sandwiched by two plates of fused quartz glass or high-silica glass, of which one is made from transparent glass and serves to provide an optical surface having flatness or a specified curvature, and the side surface of the porous foamed disc body is protected against environmental influences by providing an air-tight sealing layer formed from a silicone rubber-based sealing agent or a thin sheet of fused quartz glass or high-silica glass.