Abstract: A wear-resistant member formed comprises a sintered ceramic body essentially consisting of 0.1 to 15% by weight of at least one material selected from the group comprising molybdenum carbide, niobium carbide, hafnium carbide, tantalum carbide, tungsten carbide, molybdenum silicide, niobium silicide, hafnium silicide, tantalum silicide, tungsten silicide, molybdenum boride, niobium boride, hafnium boride, tantalum boride, and tungsten boride, 2 to 20% by weight of a boundary phase selected from the group consisting of Si--Y--Al--O--N and Si--Y--Al--O--N--B, and a balance of .beta.-silicon nitride. The wear-resistant member preferably has a metal member bonded to the sintered ceramic body. The wear-resistant member can perform high-load work such as high-speed cutting.

Abstract: A cylinder liner for use in an internal combustion engine which is formed of ceramic material having a density higher than 95% of theoretical value and a randomly directed and homogeneous structure. The ceramic liner is composed of silicon nitride, silicon carbide, an oxynitride such as silicon oxynitride and silicon aluminum oxynitride, silicon nitride-silicon carbide or aluminum nitride.

Abstract: A prechamber cup for an internal combustion engine which is made of ceramic material and designed to have a sintered and surface finished exterior wall which is to be fit in a cylinder head, a sintered and surface finished passage portion through which a gas is passed and a sintered interior wall forming cup-shaped portion.

Abstract: A corrugated radial spacer expander to be combined with side rails to form a compound oil scraping ring for internal combustion engines. The spacer expander has an annular shape cut at a portion thereof to present two opposing ends and has a corrugation consisting of successively alternating valleys and crests which are connected by intermediate flanks. At each one of said ends, there is formed a protrusion which bridges the neighbouring flanks over a valley adjacent the end, which protrusion is so shaped and positioned to prevent the valley at one end from being received by the valley at the other end, thereby ensuring that the opposing ends are correctly positioned in end to end relation, which would otherwise deteriorate the expansion force of the expander to make the oil scraper ring inoperative.