Abstract: A corrosion resistant material contains essentially WC, and 0.1 to 10 weight-%, preferably 0.5 to 5 weight-%, of one or more of the metallic carbides TiC, VC, NbC, TaC, Cr.sub.3 C.sub.2, ZrC or combinations thereof or with WC, and either spherical graphite and/or spherical hexagonal BN up to 10 volume-% with a size of about 3 .mu.m or 1-5 weight % of one or more of VN, Ti(C,N), CrN, ZrN. In applications with sliding surfaces, it has been found that the material has surprising results regarding low friction characteristics.

Abstract: A hard drive disk substrate is formed of a multi-phase ceramic-based material having at least two phases with amorphous phases being present in an amount less than about 1 volume percent based on the volume of the ceramic-based material or at least one phase being free metal. A process for producing the ceramic-based disk substrate is produced by forming a flat disk of a porous ceramic and then infiltrating the porous ceramic with a metal whereby a multi-phase ceramic-based computer hard drive disk is produced. Additionally, a step of passivating the porous ceramic by elevating it to a temperature of about 1300.degree. to about 1800.degree. C. before the infiltrating step may be performed, such that the surfaces are passivated and the reaction kinetics can be controlled during the infiltrating step. A preferred composite material is made of a multi-phase boron carbide composite material including grains having peaks with an average roughness value, Ra, of between about 1 to about 200 .ANG.

Abstract: A spray operation method for monolithic refractories, which comprises forcibly sending to an application field by a force feed pump and a force feed piping a self flowable mixed batch prepared by mixing, together with water, a powder composition for monolithic refractories comprising refractory aggregates, a refractory powder and a small amount of a dispersant; injecting into the mixed batch, compressed air and a required amount of a rapid setting agent respectively from a compressed air injection inlet and a rapid setting agent injection inlet provided at a downstream portion or downstream portions of the force feed piping; sending the mixed batch together with the compressed air by a nozzle piping to a spray nozzle attached to the forward end of the nozzle piping; and spraying the mixed batch from the spray nozzle to an application site.

Abstract: A submicrometer transition metal carbonitride is produced having the formula:M.sub.a M'.sub.b M".sub.(1-a-b) (C.sub.1-x) N.sub.x).sub.zwherein M is Ti, Zr or Hf; M' is V, Nb or Ta; M" is Cr, Mo or W; a ranges from 0 to 1; b ranges from 0 to 1 with the proviso that (a +b) is less than or equal to 1; x ranges from about 0.02 to about 0.95 and z ranges from about 0.9 to about 2. The transition metal carbonitride is produced by mixing (a) a transition metal oxide source of a transition metal in the above formula and (b) a carbon source such as carbon black.

Abstract: Disclosed is a method of forming tamper-proof coatings on electronic devices. The method comprises applying a coating of a silica precursor resin and an inorganic salt onto the electronic device, wherein the inorganic salt is one which reacts with a wet etch to yield an acid or base that damages the electronic device. The coated electronic device is then heated at a temperature sufficient to convert the silica precursor resin to a silica containing ceramic matrix.

Abstract: A matrix powder for formation along with an infiltrant into a matrix for use as a wear element or for use in retaining at least one discrete hard element. The matrix powder includes crushed sintered cemented tungsten carbide particles. The composition of the crushed sintered cemented tungsten carbide comprises between about 6 weight percent and about 13 weight percent binder metal and between about 87 weight percent and about 94 weight percent tungsten carbide.

Abstract: A matrix powder for formation along with an infiltrant into a matrix for use as a wear element or for use in retaining at least one discrete hard element. The matrix powder including macrocrystalline tungsten carbide particles, crushed sintered cemented macrocrystalline tungsten carbide particles, tungsten carbide, and an iron-based component.

Abstract: An improved hard facing for teeth and other surfaces of milled tooth rock bits comprises steel in the range of from 18 to 32 percent by weight, and filler in the range of from 68 to 82 percent by weight. The filler is cemented tungsten carbide and cast tungsten carbide free, and includes greater than 95 percent by weight single crystal monotungsten carbide particles. The single crystal monotungsten carbide particles have a particle size in the range of from 200 to 500 mesh and, preferably in the range of from 200 to 325.

Abstract: A method for preparing a ceramic composite having a core/bulk of tetragonal zirconia alloy and a shell/surface comprising zirconium boride by sintering a zirconia or zirconia and alumina composite article in an argon atmosphere while in contact with boron carbide.

Abstract: A process for producing a ceramic having a microstructured surface with a surface profile depth of less than 1 micron, measured by the atomic force microscopy, comprising preparing a polymeric precursor material, shaping the precursor material into a structured mold insert of an inherently stable mold insert material having a structured surface geometry corresponding with the microstructured surface of the ceramic to form a shaped precursor material, the shaped precursor material being rendered infusible by chemical crosslinking, and wherein the inherently stable mold insert material is selected from materials having sufficient strength for structuring and high molding accuracy, and pyrolyzing the shaped precursor material, whereby the ceramic having the microstructured surface is obtained.

Abstract: A ceramic porous body for a filter or a catalyst carrier, having a structure in which voids each having the same volume as that of a sphere of 10 .mu.m to 500 .mu.m in diameter are formed and the voids are communicated with each other through smaller fine pores, the ceramic porous body having a volume fraction of the voids and the fine pores of from 15% to 60% and being formed of components 70% or higher by volume of which is silicon nitride.

Abstract: A tungsten carbide-containing material in which the tungsten carbide has the general formula, W.sub.x C, wherein x is greater than one and less than two and the material has less than 0.20 weight percent cobalt, a density of at least about 97% of its theoretical density, and a Vickers hardness of at least about 2400 kg/mm.sup.2.

Abstract: This invention relates generally to a novel directed metal oxidation process which is utilized to produce self-supporting bodies. In some of the more specific aspects of the invention, a parent metal (e.g., a parent metal vapor) is induced to react with at least one solid oxidant-containing material to result in the directed growth of a reaction product which is formed from a reaction between the parent metal and the solid oxidant-containing material. The inventive process can be utilized to form bodies having substantially homogeneous compositions, graded compositions, and macrocomposite bodies. In a preferred embodiment, the reaction product may be chemically modified or a different reaction product may be coated thereon. Specifically, once a first reaction product is formed on a solid oxidant-containing material, the formed body may be exposed to a vapor-phase parent metal different from the first parent metal.

Abstract: Hard disk drive components, such as, sliders, load beams, support arms, actuators, actuator bearings, spacers, clamps, spindles, ball bearings, thrust bearings, journal bearings, base plates, housings, and covers, formed of a multi-phase ceramic-based material. One method of making the hard disk drive components includes (a) forming a porous body of ceramic; (b) infiltrating a liquid into the pores of the ceramic body; (c) solidifying the infiltrated liquid; and (d) machining the metal-infiltrated ceramic body to form the hard disk drive component.

Abstract: A composite ceramic wafer including a beta silicon carbide layer. The composite ceramic wafer is useful for making thin film magnetic heads.

Abstract: A composite and pressureless sintering process for making whisker-reinforced alumina composites using about 1 to about 7.5 wt. % of a nitride modifier consisting essentially of silicon nitride, aluminum nitride, or mixtures thereof that produces a sintered body having a density of greater than 95% theoretical.

Abstract: Non-magnetic ceramics for recording/reproducing heads comprising an alumina and any one of a compound selected from silicon carbide, boron carbide, zirconium carbide, titanium oxide, aluminum boride or zirconium boride, said ceramics having a Young's modulus of not smaller than 370 Gpa and a surface coarseness Ra after milling of not larger than 100 nm, and a method of producing the same.

Abstract: The present invention is embodied in a method of producing a ceramic foam. The steps for producing the ceramic foam include first mixing a liquid pre-ceramic resin with a liquid phenolic resin, second allowing the resultant mixture to chemically foam, third curing the mixture for a time and at a temperature sufficiently to convert the mixture to a polymeric foam, and then heating the resultant polymeric foam for a time and at a temperature sufficiently to completely break-down polymers of the polymeric foam and convert the polymeric foam to a ceramic foam.

Abstract: A polycrystalline cubic boron nitride cutting tool is from 50 to 85% by weight cubic boron nitride crystals bonded together as a polycrystalline mass. A supporting phase commingled with the polycrystalline cubic boron nitride is made from 15 to 40% by weight of a refractory material which is preferably titanium carbonitride or titanium aluminum carbonitride. The starting composition also comprises from 4 to 10% by weight of Co.sub.2 Al.sub.9. Mixed powders of these ingredients are treated in ammonia at a temperature in the range of from 1000.degree. to 1250.degree. C., which significantly increases the nitrogen content and reduces carbon content of titanium carbonitride. Instead of mixed powders of the starting materials, coated particles may be used such as cubic boron nitride coated with titanium carbonitride, or titanium carbonitride coated with cobalt, aluminum or cobalt aluminide. Hexagonal boron nitride may be substituted as a starting material for a portion of the cubic boron nitride.

Abstract: A silicon nitride sintered body has a composition consisting essentially of 85 to 94% by weight .beta. silicon nitride, 6 to 15% by weight grain boundary phase consisting essentially of (i) at least two rare earth elements, wherein yttrium is considered a rare earth, and, optionally, strontium which, calculated as SrO, is 02 percent by weight of the total body, and (ii) at least two of Si, N, O and C, and an additive consisting essentially of a metal carbon compound present in the amount of about 0.2 to 3.5% by volume. The additive is substantially homogeneously dispersed within the sintered body. The sintered body has a microstructure wherein (i) the .beta. silicon nitride grains are acicular and have an average grain width ranging from 0.5 to 1.5 .mu.m, (ii) at least 25% of the grains have width greater than 0.7 .mu.m, and at least 10% of the grains have width greater than 1 .mu.m, and (iii) no more than 5% of grains have width greater than 3.5 .mu.

Abstract: The invention relates to a substrate made from a novel type of ceramic material. This material comprises 44-47 at. % A1, 31-39 at. % O, 8-13 at. % C and 8-12 at. % N. Substrates made from this material exhibit a relatively high heat conductance, a relatively great strength and their coefficient of expansion is equal to that of Si. Consequently, the substrates in accordance with the invention are very suitable for use in the Si-semiconductor technology. The main component of the ceramic material of the substrates preferably corresponds to the formula Al.sub.28 O.sub.21 C.sub.6 N.sub.6. The invention also provides methods of manufacturing substrates and other mouldings from this material.

Abstract: A densified titanium diboride based ceramic composition is provided having W and Co therein and a fine grain size. The composition has particular usefulness as a cutting tool for the machining of titanium based alloys at high speeds.

Abstract: There is disclosed a method for producing a self-supporting ceramic body by oxidation of a molten precursor metal with a vapor-phase oxidant to form an oxidation reaction product and inducing a molten flux comprising said molten precursor metal through said oxidation reaction product. A second metal is incorporated into said molten flux during the oxidation reaction. The resulting ceramic body includes sufficient second metal such that one or more properties of said ceramic body are at least partially affected by the presence and properties of said second metal in the metallic constituent.

Abstract: This invention relates to a black glass fiber which is resistant to oxidation at a temperature of about 1350.degree. C. and has the empirical formula SiC.sub.x O.sub.y where x ranges from about 0.5 to about 2.0 and y ranges from about 0.5 to about 2.0. This invention also relates to a process for preparing a black glass fiber comprising reacting a silicon hydride group with a silicon olefinic group in the presence of a hydrosilylation catalyst to give a cyclosiloxane polymer. The polymer is then spun into fiber, hardened and then pyrolyzed to give a black glass fiber.

Abstract: Lightweight, monolithic ceramics resistant to oxidation in air at high temperatures are made by impregnating a porous carbon preform with a sol which contains a mixture of tetraethoxysilane, dimethyldiethoxysilane and trimethyl borate. The sol is gelled and dried on the carbon preform to form a ceramic precursor. The precursor is pyrolyzed in an inert atmosphere to form the ceramic which is made of carbon, silicon, oxygen and boron. The carbon of the preform reacts with the dried gel during the pyrolysis to form a component of the resulting ceramic. The ceramic is of the same size, shape and form as the carbon precursor. Thus, using a porous, fibrous carbon precursor, such as a carbon felt, results in a porous, fibrous ceramic. Ceramics of the invention are useful as lightweight tiles for a reentry spacecraft.

Abstract: There is now provided a ceramic material comprising of alumina, 10-50% by volume, preferably 20-35% by volume, silicon carbide whiskers, 1-25% by volume, preferably 5-20% by volume, most preferably 7-15% by volume, zirconia and 1-20% by volume, preferably 3-15% by volume, titanium compound-containing cubic phase. If this cubic phase has a lattice spacing of 4.29 to 4.40 .ANG. and a zirconium content of 3-65 weight %, a material with improved performance when turning heat resistant material such as aged Iconel 718, is obtained.

Abstract: A method of forming a low level carbon high-density tungsten carbide-containing material includes sintering a preform which contains tungsten carbide powder and has a composition such that the resulting sintered material has at most 6.05 weight percent tungsten-bound carbon based on the total weight of tungsten and tungsten-bound carbon. This low level of carbon may be achieved by, prior to the sintering step, oxidizing the tungsten carbide powder sufficiently to achieve the desired substoichiometric carbon level in the sintered product or by adding a carbon-lowering material selected from the group consisting of tungsten, ditungsten carbide, and tungsten oxide. Optionally, other materials can be present in the preform such as carbon-getter metals and compounds thereof. The carbon-getter metals are those metals of which the carbides thereof are more thermodynamically stable than monotungsten carbide.

Abstract: Substrate materials for magnetic heads consisting of 24-75 mol % of .alpha.-Al.sub.2 O.sub.3 and the remaining 76-25 mol % of TiC.sub.x O.sub.y N.sub.z containing a small amount of additives, that has a NaCl-type structure which retain known characteristics required on such materials and have controlled sizes of crystallites of Al.sub.2 O.sub.3 and TiC.sub.x O.sub.y N.sub.z, uniformly dispersed TiC.sub.x O.sub.y N.sub.z crystallites and, if any, additive elements, in which internal stress is relieved. The materials are intended for eliminating problems in IBE to form steps and thus for fabricating high-precision thin-film heads for high-density recording.

Abstract: Substrate materials for magnetic heads consisting of 24-75 mol % of .alpha.-Al.sub.2 O.sub.3 and the remaining 76-25 mol % of TiC.sub.X O.sub.Y N.sub.Z, or TiC.sub.X O.sub.Y N.sub.Z containing a small amount of additives, that has a NaCl-type structure which retain known characteristics required on such materials and have controlled sizes of crystallites of Al.sub.2 O.sub.3 and TiC.sub.X O.sub.Y N.sub.Z, uniformly dispersed TiC.sub.X O.sub.Y N.sub.Z crystallites and, if any, additive elements, in which internal stress is relieved. The materials are intended for eliminating problems in machining to form steps and thus for fabricating high-precision thin-film heads for high-density recording.

Abstract: An improved fiber reinforced glass composite includes a carbon fiber in a matrix of a black glass ceramic having the empirical formula SiCxOy where x ranges from about 0.5 to about 2.0, preferably 0.9 to 1.6 and y ranges from about 0.5 to 3.0, preferably 0.7 to 1.8. Preferably the black glass ceramic is derived from cyclosiloxane monomers containing a vinyl group attached to silicon and/or a hydride-silicon group. Graceful failure can be obtained when the carbon fibers are highly graphitized.

Abstract: A high performance ceramic composite containing tungsten carbide reinforced chromium carbide matrix in which 5.about.35 vol % of tungsten carbide particles are uniformly dispersed in 65.about.95 vol % of chromium carbide matrix. The diameters of the tungsten carbide and chromium carbide particles are preferably in the rage between 0.1.about.10 .mu.m, and their average diameters are preferably at about 2.0 and 1.5 .mu.m, respectively. The tungsten carbide/chromium carbide composite is prepared from a sintering process by applying heat and pressure to a green compact containing tungsten carbide and chromium carbide particles, without using a metallic sintering aid.

Abstract: A founder's black for producing mould coatings is disclosed, whose main component consists of finely ground refractory to highly refractory inorganic materials. The black wash contains 1 to 40% by weight inorganic hollow spheres, in relation to the ready-to-use black wash. It may further contain 0.1 to 10% by weight of inorganic or organic fibers, in relation to the ready-to-use mould coating. The hollow spheres are preferably filled with an inert gas. They may consist of oxides such as aluminium oxide, quartz, magnesite, mullite, chromite, zircon oxide and/or titanium oxide, or borides, carbides and nitride such as silicium carbide, titanium carbide, or carbon, glass or metals, or mixtures thereof. The fibres have 1 to 30 .mu.m diameter, preferably 3 to 10 .mu.m and 10 to 5000 .mu.m length, preferably 100 to 500 .mu.m length.

Abstract: Strengthened and toughened ceramic composite bodies are achieved through the use of a silicon boride composition of silicon borides and borides of the form Si-B-C. This strengthening and hardening is achieved when the silicon boride composition is present over a wide range, although a preferred amount is about 20 wt. %. This strengthening and toughening occurs for oxides, carbides, nitrides, and mixtures thereof, for example. One silicon boride composition for this application is silicon hexaboride. Further enhancement is achieved by the addition of up to about 25 wt. % carbon in the silicon hexaboride. Accordingly, the preferred silicon boride composition is a Si-B-C composition, with carbon being added to SiB.sub.6, for example.

Abstract: The invention relates to a substrate made from a novel type of ceramic material. This material comprises 44-47 at. % Al, 31-39 at. % O, 8-13 at. % C and 8-12 at. % N. Substrates made from this material exhibit a relatively high heat conductance, a relatively great strength and their coefficient of expansion is equal to that of Si. Consequently, the substrates in accordance with the invention are very suitable for use in the Si-semiconductor technology. The main component of the ceramic material of the substrates preferably corresponds to the formula Al.sub.28 O.sub.21 C.sub.6 N.sub.6. The invention also provides methods of manufacturing substrates and other mouldings from this material.

Abstract: A method of making metallic carbide powders includes heating a non-static solid reactant mixture of a metal oxide and a source of carbon to a first elevated temperature which is sufficient to cause at least partial carburization of the mixture. The heating is performed in a non-reducing atmosphere having a total pressure of at least one atmosphere for a sufficient time to form a partially-carburized mixture. The source of carbon is employed at a level which is less than the stoichiometric amount needed to produce the metallic carbide. The method may further include admixing a sufficient level of a source of carbon to the partially-carburized mixture to form an adjusted mixture having a total carbon content of the stoichiometric amount needed to make the metallic carbide and carburizing the adjusted mixture in a hydrogen-containing atmosphere at a second elevated temperature which is sufficient to cause the adjusted mixture to form the metallic carbide having a particle size of less than 0.

Abstract: Densified refractory carbide and solid solution carbide materials that have an average grain size of less than 1.1 .mu.m, a density of at least 98% of theoretical may be prepared by any conventional densification procedure. Pressure densified tungsten carbide ceramic materials exhibit a simultaneous increase in Vickers hardness and a toughness (K.sub.IC) with decreasing average grain size.

Abstract: This invention relates to the preparation of a highly densified boron carbide ceramic body by the pyrolysis of a mixture comprising boron carbide powder and a preceramic organosilicon polymer selected from the group consisting of polysiloxanes, polysilazanes, polysilanes, metallopolysiloxanes and metallopolysilanes. Such highly densified ceramic bodies can be prepared by sintering under pressure or by utilizing a pressureless process.

Abstract: A composite material includes boron carbide and titanium diboride in a volume ratio B.sub.4 C/TiB.sub.2 of from 90:10 to 10:90 parts and a proportion of elemental carbon greater than 2% by weight up to a maximum of 50% by weight, based on the boron carbide content. The composite material has a density greater than 92% TD, a hardness HK 0.1 greater than 2300, a four-point flexural strength greater than 400 MPa and a fracture toughness greater than 3.5 MPa.sqroot.m. The composite material is suitable for producing wear-resistant components or cutting tools.

Abstract: The invention is a process for decomposing dried paint sludge to recover the organic and inorganic components of the paint sludge as gaseous, liquid, and composite materials. The process comprises drying the paint sludge to remove water and organic solvents, pyrolizing the dried paint sludge in an inert atmosphere in an elevated temperature of up to about 600.degree. C. to form gaseous and liquid decomposition materials and a solid residue. The process further comprises collecting the gaseous and liquid decomposition materials and subjecting the solid residue to sintering in an elevated temperate of about 900.degree. to 1300.degree. C. in an atmosphere of nitrogen, argon or ammonia to convert the solid residue to composite materials comprising barium nitranate and titanium compounds such as titanium dioxide, titanium nitride, and titanium carbide. The gaseous and liquid materials may be further pyrolyzed to carbon materials.

Abstract: A rapid process for the preparation of diamond articles in which a porous, dense preform of diamond particles created by particle packing methods is subjected to forced flow chemical vapor infiltration of a carbon containing reagent gas resulting in the preparation of thick diamond articles.

Abstract: The invention relates to an abrasive material based on .alpha.-Al.sub.2 O.sub.3 and ZrO.sub.2 with a content of titanium compounds in the form of suboxides, carbides and/or oxycarbides, to a process for its production and to its use.

Abstract: A zirconia based composite material with improved strength and toughness includes a partially stabilized zirconia including 1.5 to 4.5 mol % of yttrium oxide as a matrix thereof and a metal phase of at least one metal selected from the group consisting of titanium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten as metal grains dispersed in the matrix. The metal phase has a melting point higher than a sintering temperature of the partially stabilized zirconia. In addition, it is preferred that the composite material further contains a ceramic phase of at least one ceramic selected from the group consisting of Al.sub.2 O.sub.3, SiC, Si.sub.3 N.sub.4, B.sub.4 C, carbides, nitrides and borides of titanium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten as ceramic grains dispersed in the matrix. The composite material of the present invention is manufactured by the following steps.

Abstract: Disclosed are high density, sintered titanium carbide bodies comprising 2-10 wt % silicon carbide, up to 2 wt % free carbon and 88 to 98 wt % titanium carbide.

Abstract: An Al.sub.2 O.sub.3 -TiC sintered product comprising Al.sub.2 O.sub.3 as a main component and containing TiC in an amount of from 20 to 40% by weight, wherein the average particle diameter of Al.sub.2 O.sub.3 particles in the sintered product is larger by 5 to 50% than the average particle diameter of TiC particles, the average particle diameter of the sintered product as a whole is not larger than 1 .mu.m, the average particle diameter of TiC particles is not larger than 0.9 .mu.m, and the total amount of the grain boundary phases other than Al.sub.2 O.sub.3 and TiC is not larger than 1.0% by weight. The Al.sub.2 O.sub.3 -TiC sintered product can be used as a substrate 1 for a magnetic head, and has portions such as grooves 4 and stepped portions formed in the surface of the air bearing surface 2 of the slider by being irradiated with ions. The sintered product exhibits excellent surface quality after machined by being irradiated with ions and can be machined at an increased rate.

Abstract: Disclosed are novel monolithic ceramic bodies of the structure SiO.sub.y C.sub.z, wherein y=1.2 to 1.6 and z=0.2-0.6. These ceramic bodies are derived from a modified hydrogen silsesquioxane resin.

Abstract: A ceramic composition comprising a polycrystalline alumina matrix having titanium carbide whiskers distributed therein. The composition comprises 50 to 90 volume percent high purity alumina, 10 to 50 volume percent single crystal titanium carbide whiskers, and up to 3 volume percent being the residue of sintering aids.

Abstract: Metal and/or metalloid nitride and/or carbide powders, e.g., amorphous or crystalline spherical particulates having a mean diameter greater than 0.2 .mu.m 90% of which being less than 0.4 .mu.m in size, well suited for the production of ceramic shaped articles exhibiting good thermomechanical properties and useful, for example, in the automotive and aeronautic fields, are prepared by flash pyrolyzing coarse drops of a precursor compound convertible into such nitride and/or carbide, at an elevated temperature and for such period of time as to convert the precursor compound into said amorphous or crystalline powder.

Abstract: This invention relates to submicron carbonitride powders of titanium and, optionally, other transition metals of the fifth (Me.sup.(5)) and sixth (Me.sup.(6)) secondary group of the periodic system of elements which have the following general molar composition: (Ti.sub.L Me.sub.M.sup.(5) Me.sup.(6).sub.1-L-M) (C.sub.1-y N.sub.y).sub.z with 0.50.ltoreq.L.ltoreq.1; 0.ltoreq.m.ltoreq.0.15; 0.ltoreq.(1-L-M).ltoreq.0.50; 0.10.ltoreq.y.ltoreq.0.95 and z.gtoreq.0.90, to a process for the production of these powders and to their use.

Abstract: A composite ceramic block gauge and its preparing method is disclosed. The ceramic block gauge comprises a tungsten carbide (WC) reinforced phase and a chromium carbide (Cr.sub.3 C.sub.2) matrix. The finished block gauge possesses excellent properties such as hardness and corrosion resistance and high reflectivity. The block gauges made from Cr.sub.3 C.sub.2 /WC composites can be calibrated using the traditional optical interferometry techniques.

Abstract: The present invention relates to a sintered body for chip forming machining containing at least one hard constituent comprising a carbide, nitride and/or carbonitride of a metal of group IVB, VB or VIB in the periodical system and a binder metal based upon Co, No and/or Fe, in which the body comprises a core containing eta-phase or an intermediate phase, substantially free of carbon and/or nitrogen surrounded by a hard constituent- and binder phase-containing surface zone, free of said eta-phase or intermediate phase.