Abstract: A silicon carbide powder consisting of an aluminum component such as aluminum nitride and aluminum oxide and a chromium component such as chromium carbide as essential ingredients and if desired, a rare earth element such as yttria is sintered into an integrated molded article. This sintered article has excellent strength and toughness and a markedly reduced tendency to undergo corrosion when brought into contact with iron at high temperatures.

Abstract: A ZrB.sub.2 composite sintered material consisting essentially of at least 1% by weight of SiC, at least 1% by weight of B.sub.4 C, at most 15% by weight of TiC, at most 35% by weight of TiN, at most 40% by weight of AlN, the rest being substantially ZrB.sub.2, provided that the total amount of SiC and B.sub.4 C is from 2 to 50% by weight.

Abstract: A high toughness silicon nitride sintered body comprises silicon nitride as a main component and at least one member selected from the group consisting of silicides and carbides in the form of plate particles, of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W. In the sintered body, the longer diameter d.sub.1 of principal plane of plate of the plate particles and the shorter diameter d.sub.2 of the same plane has a relation of d.sub.1 /d.sub.2 <10, and the thickness of plate of the plate particles is 1/5 or below of d.sub.2.

Abstract: Hard, tough, lightweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidation step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modulus of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi.sqroot.in. These composites and methods can be used to form a variety of structural elements.

Abstract: A method of producing a composite compact of cBN and WC-Co, comprising: mixing fine particles of cBN with a minor part of titanium carbide, the former being in an amount of 60-80% and the latter 40-20%, correspondingly, of the combined volume, putting the mixture in an intimate contact with a composite of WC-Co, heating the whole to a temperature high enough to cause an outflow of a liquid phase from said composite and infiltration thereof into said mixture under a pressure-temperature condition where cubic boron nitride is crystallographically stable, interjoining adjacent particles of cBN and titanium carbide, and as a whole to the composite of WC-Co, and recovering the integrated product of cBN, titanium carbide and WC-Co.

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: Sialon-base ceramic materials having both high hardness and good sinterability and can show excellent wear resistance when used in cutting tools and other wear-resisting tools. A Sialon-base ceramic material according to the invention has main components consisting of .beta.-Sialon expressed by a chemical formula Si.sub.6-z Al.sub.z O.sub.z N.sub.8-z, z being larger than 0 but not more than 4.3, and .alpha.-Sialon expressed by a chemical formula M.sub.x (Si, Al).sub.12 (O,N).sub.16, x being larger than 0 but not more than 2, M representing at least one selected from the group consisting of Li, Na, Ca, Mg, Y, and any rare earth element, the ratio of the .alpha.-Sialon/the .beta.-Sialon being within a range from 25/75 to 95/5 in volume.

Abstract: A particulate mixture of ceramic powder, boron and a hydride of a metal selected from the group consisting of hafnium, niobium, tantalum, titanium, vanadium, zirconium and mixtures thereof is hot pressed decomposing the hydride and reacting the resulting metal with boron producing a polycrystalline microcomposite comprised of a continuous phase of the boride of the metal which encapsulates at least about 20% by volume of the ceramic particles and which either encapsulates or is intermixed with the balance of said ceramic particles.

Abstract: A particulate mixture of ceramic powder, free carbon and a hydride of a metal selected from the group consisting of hafnium, niobium, tantalum, titanium, vanadium, zirconium and mixtures thereof is hot pressed decomposing the hydride and reacting the resulting metal with carbon producing a polycrystalline microcomposite comprised of a continuous phase of the carbide of the metal which encapsulates at least about 20% by volume of the ceramic particles and which either encapsulates or is intermixed with the balance of said ceramic particles.

Abstract: High-strength, fine-grain multi-phase substantially crystalline sintered ceramic bodies are produced by a process comprising the steps of cold pressing, followed by sintering at a high temperature, the temperature increase to maximum sintering temperature being accomplished by the use of a heating rate in excess of about 100.degree. C./minute.

Abstract: Metal-ceramic composites may be prepared by treating the ceramic component of the composite with a second metal prior to subjecting the metal-ceramic composite to a sintering operation. By pretreating the ceramic component of the composite, it is possible to obtain a composite which will undergo sintering at an elevated temperature to form a composite which will possess desirable characteristics such as increased density, hardness and low thermal coefficient of expansion, thus enabling the composites to be utilized in a wide variety of applications.

Abstract: The bond between a hard wear resistant coating of Al.sub.2 O.sub.3 and a cemented carbide substrate is greatly improved by means of a more effective interlayer of TiO. The TiO layer is provided by means of a reduction process from other titanium oxides such as TiO.sub.2.

Abstract: Non-oxide powders such as carbides, nitrides, carbides/nitrides and borides are obtained by reducing an oxide powder in a reducing atmosphere, and after or concurrently with the reduction, treating the reduced powder in a carbonizing atmosphere, a nitrogenizing atmosphere, a carbonizing and nitrogenizing atmosphere, or a boronizing atmosphere. As the above oxide powder, there is used a brittle material obtained by rapid cooling of a melted oxide. The non-oxide powders obtained are utilized as a hard component of cemented carbides and cermet. These powders are fine particles having a particle size of 1.0 .mu.m or smaller and a high purity.

Abstract: Solid solutions of molybdenum and tungsten having molybdenum to tungsten atom ratios between about 1:1 and about 10:1 are produced by heating a mechanically milled mixture of a molybdenum oxide and tungsten oxide to a temperature between about 1000.degree. C. and about 1300.degree. C. at a rate of at least about 20.degree. C. per minute in a hydrogen-containing atmosphere and holding at temperature to reduce the oxides of molybdenum and tungsten and to provide a homogeneous solid solution of molybdenum and tungsten. The homogeneous solid solution is mixed with a stoichiometric excess of carbon and heated to a temperature between about 1200.degree. C. and about 1800.degree. C. under a protective atmosphere to react the carbon with the alloy powder to form a solid solution of hexagonal monocarbides.

Abstract: A composite article and cutting tool are prepared by densification to form a body consisting essentially of particles of hard refractory material uniformly distributed in a matrix consisting essentially of a first phase and a second phase, said first phase consisting essentially of crystalline silicon nitride and said second phase being an intergranular refractory phase comprising silicon nitride and a suitable densification aid comprising magnesium oxide and silicon dioxide.

Abstract: Flaky .beta.-SiC mainly composed of .beta.-SiC which is obtained from an organic silicon polymer containing the carbon and silicon atoms as the major skeletal component and the method for producing such flaky .beta.-SiC are disclosed. Such .beta.-SiC is especially utilized as the starting material for ceramics having a laminar structure as well as for the refractories. The ceramics and refractories provided with such .beta.-SiC have excellent resistance to thermal shock, to thermal fatigue as well as to oxidation.

Abstract: The invention provides a novel highly refractory sintered body based on a tal diboride such as TiB.sub.2 or Mo.sub.2 B.sub.5 and W.sub.2 B.sub.5 containing a binder ingredient. The high-temperature performance of the sintered body is further improved by including an auxiliary additive ingredient selected from several carbides, nitrides, silicides and oxides such as WC, TiC, TaN, TiN, MoSi.sub.2, TiO.sub.2, Al.sub.2 O.sub.3, B.sub.2 O.sub.3 and the like in a limited amount.

Abstract: Sintered cubic boron nitride consisting of 80 to 20% by volume of the following component (a), with the balance being essentially the following component (b), and a process for producing such nitride are disclosed:(a) cubic boron nitride;(b) a cermet containing the following sub-components (1), (2) and (3):(1) TiC and/or TiC-TiN, part of which may be replaced by a carbide, a nitride, a boride and/or a silicide of a transition metal of the group IVa, Va and VIa of the Periodic Table;(2) Fe, Co and/or Ni; and(3) Mo and/or Mo.sub.2 C.

Abstract: Sintered bodies having improved sinterability and toughness consist essentially of: (1) 100 parts by weight of titanium carbide, titanium oxide and aluminum oxide, the titanium carbide and titanium oxide accounting for 15 to 60 percent by weight and the aluminum oxide accounting for 85 to 40 percent by weight, the amount of titanium oxide relative to the titanium carbide and titanium oxide being 5 to 15 percent by weight, and (2) 0.039 to 1.575 parts by weight of yttrium. Sintering aids may include at least one of the oxides of magnesium, nickel, molybdenum, chromium, cobalt, iron and manganese.

Abstract: A process for the preparation of an extrahard material based on tungsten and molybdenum carbides and having a hexagonal crystal structure identical with that of tungsten carbide. According to this process, one heats between 1000.degree. C. and a temperature T.sub.x, which is lower than the maximum stability limit of the Mo.sub.x W.sub.l-x C phase wherein 0.01.times.1, a mixture, intimate to the molecular or atomic scale, of tungsten and molybdenum the total content of which in Fe, Ni and Co does not exceed 0.1% with carbon and/or a carbon compound.T.sub.x is defined as follows:For 0.01<.times.<0.8, T.sub.x =2700-1375x.degree.C;For 0.8<.times.<1, T.sub.x =3400-2250x.degree.C.

Abstract: An agglomerated mixture includes 30-95% by weight of highly dispersed metal oxides produced by flame hydrolysis and 5-70% by weight of inorganic opacifiers that have at least one absorption maximum in the range between 1.5 and 10 .mu.m, selected from the group consisting of inorganic oxides and mixed oxides, carbides and nitrides. The invention also relates to a process of manufacturing the mixtures and to their use as heat-insulating material and the like.