Abstract: Disclosed is a sintered Ti-based material product derived from injection molding of a powder material. The outer layer region of the product comprises a lower amount of carbon than the inner layer region of the same. The inner layer region comprises a Ti-based carbide which has an average grain size of not less than 1 &mgr;m and which is dispersed in the inner structure to have an area fraction of not less than 0.1% to not more than 20%. The outer layer region comprises a lower amount of Ti-based carbide than the inner layer region. There can be observed an area fraction of less than 0.1% of the Ti-based carbide at the surface of the sintered Ti-based material product.

Abstract: By forming corner parts of transparent quartz plates and the glass plate in rounded arc shape, in a mirror-surface finishing to accurate plane, polishing powder grain can flow out smoothly and evenly from all the periphery of the plates, and thus the surfaces of those component plates are finished to accurate plate of mirror-surfaces, without making a recessed part at their central parts which has been observed in the conventional plates of rectangular form, and hence, a quartz optical filter made by laminating the improved plates having accurate planes attains an excellent performance characteristic which does not give any degradation in light propagation.

Abstract: Inorganic fillers such as silica balloons are used as a lightweight filler for resin moldings. But the specific gravity of these inorganic fillers is about 0.2 at most, so that there is a limit to reduction in weight. The foamed product of organic polymers is obtained as a lightweight substance, but it is hardly put to practical use because of its poor solvent resistance and thermal resistance.The microballoon of the present invention is produced by coating the surface of a hollow particle having the wall film of a thermoplastic high polymer with a thermosetting resin.The present invention provides a microballoon having excellent solvent resistance and thermal resistance as well as a very low specific gravity, and said microballoon is useful as a lightweight filler for resin moldings, aggregate for FRP, ingredient for paints, and the like.