Abstract: The present invention is characterized by ceramic materials comprising ceramic sintered bodies consisting of (1) 1-90 wt % chromium carbide and the remainder carbonic titanium nitride; (2) 1-90 wt % chromium carbide, 0.1-5 wt % B.sub.4 C and the remainder titanium carbo-nitride; or (3) either of the above compositions plus less than 95 wt % of a metal boride such as Ti or Zr. Such ceramic sintered bodies are used for cutting tools or wear-resistant machine parts because of their high density, high hardness and high strength.

Abstract: A filter medium which permits an increased amount of filtration. The filter medium can be prepared by blending 100 parts by weight of aggregate particles, 5-18 parts by weight of an inorganic bonding material having a chemical composition of about 10-50% by weight of SiO.sub.2 and about 5-20% by weight of B.sub.2 O.sub.3 and containing at least 70% by weight of a non-vitreous substance such as talc or boric acid, and about 3-15 parts by weight of a combustible substance such as wheat flour, kneading the mixture with a caking material and water, molding the kneaded mixture, drying it, and then calcining the dried mixture at a temperature not lower than about 1100.degree.C. The size and number of the air-permeable pores in the filter medium can be controlled by adjusting the amounts of the bonding material and combustible substance.