A synthesis method for producing a refractory oxide-ceramic material of CaZrO.sub.3, in particular in the form of a refractory granular material that is preferably mechanically comminuted, in particular crushed and/or ground, as well as to a batch and a coarse ceramic, shaped or unshaped, refractory product containing at least one pre-synthesized refractory calcium zirconate-containing granular material.

Antiballistic armour plate includes a ceramic body including a hard material, provided, on its inner face, with a back energy-dissipating coating. The ceramic body is monolithic. The constituent material of the ceramic body includes grains of ceramic material having a Vickers hardness that is higher than 15 GPa, and a matrix binding the grains, the matrix including a silicon nitride phase and/or a silicon oxynitride phase, the matrix representing between 5 and 40% by weight of the constituent material of the ceramic body. The maximum equivalent diameter of the grains of ceramic material is smaller than or equal to 800 micrometres. The constituent material of the ceramic body has an open porosity that is higher than 5% and lower than 14%. The metallic silicon content in the material, expressed per mm of thickness of the body, is lower than 0.5% by weight.

The present disclosure provides a boron carbide composite material having a novel composition with excellent mechanical properties, and a production method therefor. The boron carbide composite material has high fracture toughness and may be applied as a lightweight bulletproof ceramic material. The boron carbide composite material is a boron carbide/silicon carbide/titanium boride/graphite (B.sub.4C—SiC—TiB.sub.2—C) composite material. The composite material may overcome a technical limitation on increasing the fracture toughness of the boron carbide composite material, and may be produced as a high-density boron carbide composite material using a reactive hot-pressing sintering process at a relatively low temperature. The boron carbide composite material having excellent mechanical properties may be applied to general industrial wear-resistant parts and nuclear-power-related industrial parts, and particularly, may be actively used as a lightweight bulletproof material for personal use and for military aircraft including helicopters.

A cubic boron nitride particle population having highly-etched surfaces and a high toughness index is produced by blending a reactive metal powder with a plurality of cubic boron nitride particles to form a blended mixture. The blended mixture is compressed to form a compressed mixture. The compressed mixture is subjected to a temperature and a pressure, where the temperature is controlled to cause etching of the plurality of cubic boron nitride particles by reaction of cubic boron nitride with the reactive metal powder, thereby forming a plurality of etched cubic boron nitride particles. Also, the temperature and pressure are controlled to cause boron nitride to remain in a cubic boron nitride phase. Afterwards, the plurality of etched cubic boron nitride particles is recovered from the compressed mixture to form the particle population. Preferably, the particle population contains no hexagonal boron nitride.

The invention relates to a method for producing a ceramic moulded body, comprising the following steps: a) producing a green body containing ceramic material, binding agents and an organic pore forming agent; b) heating the green body to a temperature equal to or higher than the sublimation temperature of the pore forming agent; c) burning the green body to form a ceramic moulded body. According to the invention that the organic pore forming agent is selected from the group consisting of dicarboxylic acids and mixtures of dicarboxylic acids, the sublimation temperature being at least 80 k lower than the decomposition temperature.

A method of producing a graphite-containing refractory within which carbon fiber bundles are placed, the graphite constituting 1% to 80% by mass, the method including a bundling step of bundling carbon fibers to form the carbon fiber bundles; a mixing step of mixing a refractory raw material with graphite to prepare a graphite-containing refractory raw material; a pressing step of pressing the graphite-containing refractory raw material in which the carbon fiber bundles are placed to prepare a formed product; and a drying step of drying the pressed product, wherein the bundling step includes bundling 1000 to 300000 of the carbon fibers with a fiber diameter of 1 to 45 μm/fiber to form carbon fiber bundles 100 mm or more in length.

The invention discloses a sound-absorbing material particle and a preparation method thereof. The method for preparing the sound-absorbing material particle comprises: mixing a sound-absorbing raw material with a solvent to form a sound-absorbing slurry; filling the sound-absorbing slurry into a mechanical compression die, and performing compression molding on the sound-absorbing slurry to form a particle; performing a hydrothermal crystallization reaction on the particle to crystallize the sound-absorbing raw material in the particle; and drying the particle to produce the sound-absorbing material particle.

Embodiments of disclosure may provide a method for forming an aluminum-containing nitride ceramic matrix composite, comprising heating a green body, an aluminum-containing composition, ammonia and a mineralizer composition in a sealable container to a temperature between about 400 degrees Celsius and about 800 degrees Celsius and a pressure between about 10 MPa and about 1000 MPa, to form an aluminum-containing nitride ceramic matrix composite characterized by a phosphor-to-aluminum nitride (AlN) ratio, by volume, between about 1% and about 99%, by a porosity between about 1% and about 50%, and by a thermal conductivity between about 1 watt per meter-Kelvin and about 320 watts per meter-Kelvin. The green body comprises a phosphor powder comprising at least one phosphor composition, wherein the phosphor powder particles are characterized by a D50 diameter between about 100 nanometers and about 500 micrometers, and the green body has a porosity between about 10% and about 80%. The aluminum-containing composition has a purity, on a metals basis, between about 90% and about 99.9999%. The fraction of free volume within the sealable container contains between about 10% and about 95% of liquid ammonia prior to heating the green body, the aluminum-containing composition, ammonia and the mineralizer composition in the sealable container.

The invention concerns the area of ceramics an relates to a method for separating impurities from silicon carbide, said method being applicable to SiC powders from grinding sludges, and to temperature-treated and purified silicon carbide powder. The aim of the invention is to provide a method with which different impurities are substantially completely removed using a simple and economical process. This is achieved by a method in which pulverulent SiC waste products that have a mass percent of SiC of at least 50% and an average grain size d.sub.50 ranging from 0.5 to 1000 μm and have been subjected to a temperature treatment and cooled are mechanically treated and physically separated. The physically separated SiC powder is then divided into two fractions, one of which has a mass of impurities that is greater than the mass of impurities in the other fraction at least by a factor of 2.

A porous refractory cast material contains a closed refractory aggregate fraction having a minimum particle size and a maximum particle size; the ratio of maximum particle size to minimum particle size is 10:1 or less. This closed refractory aggregate fraction comprises all of the porous refractory cast material having a particle diameter greater than 0.1 mm. The porous refractory cast material also contains a binder phase containing refractory selected from calcium aluminate cement, alumina phosphate, hydratable alumina, colloidal silica and combinations thereof. Also disclosed is a metallurgical vessel with an interior lining incorporating the porous refractory cast material.