Abstract: In a sliding element having first and second members in friction and/or sealing contact, the first member s made by sintering a ceramic mixture based on silicon nitride, the content of the silicon nitride phase and/or of the silicon nitride mixed crystal phase being at least 60 weight-percent and the second counter-element member being formed of a ceramic material based on aluminum oxide.

Abstract: A tubularly formed valve guide (1) with a bore for a metal valve shank (2) for use in an internal combustion engine comprising a sintered body of a partially stabilized zirconium oxide having a porosity of less than 3%. Even under extreme stress, e.g., in an outlet valve of a high-power engine, but in particular in the blow-off valve of an exhaust gas turbocharger, the valve guide shows a considerably reduced wear as compared to conventional valve guides.

Abstract: Ceramic shaped articles are disclosed which are formed of dense, non-metallic, mechanically resistant materials and contain eutectic constituents consisting of zirconium oxide, hafnium oxide and at least one other high-melting oxide and mixtures thereof. The composition exhibits excellent hardness, wear properties and bending strength. A method for preparing the articles is also disclosed wherein the appropriate mixture in a hypoeutectic, eutectic, or hypereutectic ratio is heated to its melting point, poured into a preheated mold and cooled.

Abstract: A piston arrangement with a metal shaft, a piston head that is attached to it with a shrink ring, and a member made of partially stabilized zirconium ozide. The top which demarcates the combustion chamber, of the piston head, consists entirely of the member made of partially stabilized zirconium oxide. The bottom of the zirconium-oxide member is a truncated cone and the top of the shaft is a truncated cone. They are surrounded by an annular component that is split into two sections parallel to the longitudinal axis of the piston. The annular ocmponent is secured with an outside shrink ring.

Abstract: A thermal insulation lining (1) in the exhaust duct (4) of a cylinder head (5) consists of a sintered compact (2) of ceramic material having an envelope containing or consisting of inorganic fibers.

Abstract: In a cylinder head (1) of a piston engine, a thermal insulation component having openings for the accommodation of valve seats, spark plugs, and injection nozzles consists of a circular aluminum titanate plate (2) which is shrink-fitted into a planar circular ring of zirconium oxide (12) gripped or shrink-fitted in the cylinder head. The circular plate (2) of aluminum titanate forms the greatest part of the cylinder head bottom (9).

Abstract: A piston ring (1) made of ceramic materials for an internal combustion engine comprising a body made by sintering of partially stabilized zirconium oxide (PSZ) which has a porosity <3% and, rolling surface (4) of the piston ring having a centerline average roughness R.sub.a of 0.03 to 0.1 .mu.m. Due to its homogeneous structure, the inventive piston ring avoids the problems of the ceramic/metal bond of known piston rings and, even under high thermal load, does not suffer from thermally induced destruction or welding of the piston ring groove.

Abstract: In a pre-combustion or turbulence chamber for an internal combustion engine, an inner molded body, defining an inner chamber, is formed of a material having a thermal conductivity of at least 12 W/(m.multidot.K). An outer body is secured to the outer surface of the inner body by shrinking or glueing. The outer body is formed of a thermally insulating ceramic material having a thermal conductivity of less than 10 W/(m.multidot.K). Due to the low thermal conductivity of the outer molded body, the inner molded body is insulated against heat losses. The higher thermal conductivity of the inner molded body has the effect that, in the interior of the pre-combustion or turbulence chamber, the point at which the cold fuel jet impinges during the injection process is only slightly cooled.

Abstract: In a cylinder head of a piston engine, the surface of the cylinder head facing the combustion chamber is covered by a plate having openings for valves, spark plugs or injection nozzles. The plate consists of mullite containing 2 to 30% by volume of zirconium oxide and/or hafnium oxide embedded therein, plus 0 to 3 mole-percent of oxides of magnesium, calcium or yttrium, with respect to the zirconium and/or hafnium oxide, and of no more than 0.5%, by weight, of other oxidic impurities.

Abstract: Apparatus for processing paper wherein a pair of endless curved wire devices operate to pass therebetween a sheet material to be treated for a dewatering operation or the like. A support structure in the form of individual support segments made from sintered oxide ceramics are arranged to extend over the width of the apparatus and are in contact with one another, with a plurality of the segments being arranged consecutively in the direction of the course of the wire devices, the segments having a maximum linear expanse of 700 mm per segment and having junction areas between consecutively arranged segments defining a gap for feeding cooling water to the guide wire devices.

Abstract: A machine component is disclosed composed of 3.0 to 25 weight percent of zirconium oxide and/or hafnium oxide which are present in the interior of the machine component at room temperature predominantly in the metastable tetragonal modification and at the surface of the machine component in the monoclinic modification, said machine component having a profile bearing ratio of about 10 to 40% and an center line average surface roughness R.sub.a in the contact area of less than 0.3 .mu.m. The machine components of the present invention are leakproof, exhibit good thermal shock durability and exhibit good frictional engagement characteristics for long periods of time.