Abstract: This invention relates to a sintered body of conductive sialon and a heater element made of this sintered body. They are relieved from damage by partial expansion without any adverse effect on mechanical strength and electrical properties. According to this invention, the thickness of the oxidation layer in the sintered bodies is controlled. Thus the sintered body of sialon pertaining to this invention is formed by sintering a mixture composed of a base mixture containing Si.sub.3 N.sub.4 (major constituent), a small amount of AlN (polytype), and less than 5 wt % of Y.sub.2 O.sub.3, and a small amount of Al.sub.2 O.sub.3 and 23-70 vol % (based on the base mixture) of at least one kind of Ti carbide, Ti nitride, and Ti carbonitride.

Abstract: A wear-resistant compound roll having a shell portion produced by sintering a uniform mixture of alloy powder consisting essentially, by weight, of 1.2-3.5% of C, 2% or less of Si, 2% or less of Mn. 10% or less of Cr, 3-35%, as W+2Mo, of one or two of W and Mo, 1-12% of V, and balance Fe and inevitable impurities, and 1-15%, based on the weight of said alloy powder, of VC powder dispersed therein. This compound roll is produced by (a) uniformly mixing the alloy powder with the VC powder; (b) charging the resulting mixed powder into a metal capsule disposed around a roll core; and (c) after evacuation and sealing, subjecting said mixing powder to a HIP treatment.

Abstract: A wear-resistant compound roll having a shell portion produced by sintering a uniform mixture of alloy powder consisting essentially, by weight, of 1.2-3.5% of C, 2% or less of Si, 2% or less of Mn, 10% or less of Cr, 3-35%, as W+2Mo, of one or two of W and Mo, 1-12% of V, and balance Fe and inevitable impurities, and 1-15%, based on the weight of said alloy powder, of VC powder dispersed therein. This compound roll is produced by (a) uniformly mixing the alloy powder with the VC powder; (b) charging the resulting mixed powder into a metal capsule disposed around a roll core; and (c) after evacuation and sealing, subjecting said mixed powder to a HIP treatment.

Abstract: A diesel engine glow plug having an elongated hollow electrically conductive holder, which holds a rod-like ceramic heater at one end thereof such that one end of the heater extends outside the holder. An external connecting terminal is positioned in the other end of the hollow holder and electrically insulated from the hollow holder. The ceramic heater is a U-shaped heating element with a pair of parallel lead portions made of a resistive ceramic material extending backward from both ends of the U-shaped heating element and arranged such that the outer surfaces of the lead portions are held by the distal end of the holder through electrical insulating layers between the inner surface of the holder and the outer surface of the lead portions.

Abstract: A glow plug for a diesel engine includes a hollow holder, and a ceramic heater made of SiAlON extending through a distal end portion of the hollow holder and held by it. The ceramic heater is provided with a U-shaped heating element and a pair of lead portions extending backward from both ends of the U-shaped heating element and parallel to each other. The heating element and the pair of lead portions are integrally made of a resistive ceramic material. One of the lead portions is coupled to one end of an electrically conducting flexible wire, the other end of the wire being coupled to an external connecting terminal. A ration .epsilon.(.dbd.SH/SL) of cross-sectional areas SH of the U-shaped heating element to cross-section areas SL of the lead portions falls within the range of 0.15.ltoreq..epsilon..gtoreq.0.6.

Abstract: A glow plug for diesel engines includes a ceramic heater with a U-shaped heating portion and a pair of leads integrally formed with the heating portion and extending backwards from both ends of the heating portion. The heater is supported at one end thereof by a hollow holder in a cantilevered state with one end thereof protruding towards the outside. At least the outside surfaces of the leads are joined to, and held by, the inside of the holder via an insulating layer, and at least the rear ends of the other of the leads are connected via a metallic lead wire to an external connection terminal supported in an insulated state by the rear end of the holder. The ceramic heater is integrally formed from an electrically resistive sintered sialon produced by adding 20-70 vol. % Ti nitride or carbonitride as an electric conductivity donor to .beta.-type sialon or a .alpha./.beta.-type sialon.