Abstract: In a cell for measuring electrical conductivity, a container (2) and electrodes (1) are made of ceramics having high corrosion-resistant property. Insulating ceramics are used for the container (2), and conductive ceramics having resistance value of several k .OMEGA..cm or less is used for the electrodes (1). The ceramics are far superior to glass in corrosion resistant property and mechanical strength under normal as well as high temperature conditions. Further, the cell is produced at lower cost than the one made of precious metal and has high corrosion resistant property and can be used under strong acid or strong alkaline conditions. It has high mechanical strength and can be used under high pressure and high temperature conditions and produced at low cost because precious metal is not used for the electrodes.

Abstract: A highly corrosion resistant .alpha.-sialon-like sintered body consisting essentially of an .alpha.-sialon composition represented by the composition formulaMx(Si,Al).sub.12 (O,N).sub.16wherein M is at least one .alpha.-sialon-soluble element selected from the group consisting of Yb, Er and Dy, and 0<.times..ltoreq.0.8,and Sc.sub.2 O.sub.3 insoluble in the .alpha.-sialon composition and being in an amount of 0.01 to 15 wt % based on the weight of the sintered body, and containing as an intergranular phase a Sc.sub.2 O.sub.3 --SiO.sub.2 complex wherein the mole ratio of Sc.sub.2 O.sub.3 to SiO.sub.2 is within the range of 1:0.1 to 1:50. This sintered body has not only mechanical characteristics such as strength and toughness, but high corrosion resistance such that it can withstand use under an environment where corrosion resistance such as oxidation resistance or chemical resistance is required.

Abstract: A composite sinter of silicon nitride/boron nitride, which consists essentially of, in weight percentage, silicon nitride within the range of from 60 to 97% and boron nitride within the range of from 3 to 40%, and wherein said boron nitride is present as a dispersed phase in the network of said silicon nitride; said composite sinter of silicon nitride/boron nitride being manufactured by the steps of: kneading a silicon powder within the range of from 47.3 to 95.1 wt.% and a boron nitride powder within the range of from 4.9 to 52.7 wt. %, as raw materials, with the use of an organic solvent solution containing a dispersant and a binder; press-forming the resultant kneaded mixture to prepare a green compact; sintering said green compact in a non-oxidizing atmosphere at a temperature within the range of from 1,100.degree. to 1,300.degree. C.