Abstract: Silicon carbide matrix composite material (1) comprises silicon carbide matrix (2) as a host The silicon carbide matrix (2) comprises first silicon carbide phase (3) of 0.1 to 10 ?m average crystal grain diameter and second silicon carbide phase (4) of 0.01 to 2 ?m average crystal grain diameter. In interstices of silicon carbide crystal grains constituting the silicon carbide matrix (2), liberated silicon phase (5) amounting to, for example, 5 to 50 mass % based on the composite material (1) is present continuously in network form. This fine structure enables realizing high strength and high toughness of the silicon carbide composite material (1).

Abstract: Silicon carbide matrix composite material (1) comprises silicon carbide matrix (2) as a host. The silicon carbide matrix (2) comprises first silicon carbide phase (3) of 0.1 to 10 ?m average crystal grain diameter and second silicon carbide phase (4) of 0.01 to 2 ?m average crystal grain diameter. In interstices of silicon carbide crystal grains constituting the silicon carbide matrix (2), liberated silicon phase (5) amounting to, for example, 5 to 50 mass % based on the composite material (1) is present continuously in network form. This fine structure enables realizing high strength and high toughness of the silicon carbide composite material (1).

Abstract: A sputtering target contains Si and C as its major components and includes a texture in which a Si phase continuously exists in a net shape in gaps among SiC crystal grains. An average diameter of the Si phase is controlled to 1000 nm or less. The sputtering target is sputtered in an oxygen-containing gas, thereby depositing an optical thin film containing Si and O as its major components, and a third element other than the major components, a total amount of the third element being within a range from 10 to 2000 ppm.

Abstract: The present invention adopts a particle dispersed silicon material, comprising silicon carbide as dispersion particles, as a mirror substrate, subjects the mirror substrate to mirror finish polishing to form a mirror body, forms a reflecting film on the mirror body to form a mirror, and uses the mirror to form a large aperture optical system.

Abstract: Silicon carbide matrix composite material (1) comprises silicon carbide matrix (2) as a host. The silicon carbide matrix (2) comprises first silicon carbide phase (3) of 0.1 to 10 ?m average crystal grain diameter and second silicon carbide phase (4) of 0.01 to 2 ?m average crystal grain diameter. In interstices of silicon carbide crystal grains constituting the silicon carbide matrix (2), liberated silicon phase (5) amounting to, for example, 5 to 50 mass % based on the composite material (1) is present continuously in network form. This fine structure enables realizing high strength and high toughness of the silicon carbide composite material (1).

Abstract: The present invention adopts a particle dispersed silicon material, comprising silicon carbide as dispersion particles, as a mirror substrate, subjects the mirror substrate to mirror finish polishing to form a mirror body, forms a reflecting film on the mirror body to form a mirror, and uses the mirror to form a large aperture optical system.

Abstract: According to a ceramic fiber reinforced ceramic matrix composite material of the present invention, a ceramic fiber reinforced ceramic matrix composite material 1 comprises a composite ceramic matrix, and a preform 5 resulting from a fiber bundle 3 obtained by bundling a plurality of ceramic fibers 2 and disposed therein, and is characterized in that a first ceramic matrix M1 is formed in an inner space of the fiber bundle 3 and at a region adjacent to an outer periphery thereof, and a second ceramic matrix M2 is formed in an inner space of the preform 5 and at an outer peripheral region thereof, the space and region of the preform being defined except for those of the fiber bundle. Also characteristically, ceramic fibers are compositely disposed in a fiber volume fraction (Vf) of greater than 10% in a reaction-sintered ceramic matrix.

Abstract: There is provided a ceramic matrix composite whose strength is less degraded even in a high-temperature range at, especially, 1,400.degree. C. or higher, and a method of manufacturing the ceramic matrix composite. The ceramic matrix composite in which reinforcements are arranged in a ceramic matrix to be combined to the ceramic matrix is characterized in that the main component of the ceramic matrix consists of silicon carbide and molybdenum silicide based compound, the density ratio of the matrix is 90% or higher.

Abstract: In fiber composite ceramic containing reaction sintered SiC as a matrix and having BN-coated SiC continuous fibers as composite fibers, the thickness of the BN coating need not be especially made large, and a sliding effect during growing of cracks can be improved, i.e., breakdown energy can be increased. A method of manufacturing fiber composite ceramic in which large number of BN-coated SiC fibers covered with a BN coating are gathered to form yarns, or yarns are woven to form a two-dimensional or three-dimensional fabric, and a preform is formed by the yarns or the fabric, C powder is arranged in a gap portion between fibers of the preform to form a compact, a molten Si is impregnated into the compact to form an SiC matrix between fibers. A region having a high B concentration is formed around the SiC fibers before the preform is impregnated with the molten Si, and B in the region is solid-solved in Si during reaction sintering to suppress B in the BN-coated SiC fibers from being solid-solved in Si.

Abstract: A fiber reinforced ceramic matrix composite is disclosed which comprises a ceramic matrix and a fiber preform integrally assembled therein, the fiber preform comprising a braided fabric derivable from braiding a yarn which is composed of a plurality of fiber bundles formed of a plurality of monofilaments bundled together, the braided fabric being present in a volume fraction of fiber (Vf) of 10 to 40% by volume based on the total volume of the ceramic matrix composite. The yarns (fiber bundles) may preferably be disposed in oblique relation to each other. Initial matrix cracking strength, crack propagation resistance and fracture energy are greatly increased. Fiber preforms having a complicated shape can be easily obtained.

Abstract: A ceramic matrix composite material comprising a matrix containing silicon carbide as the primary component and silicon nitride as the secondary component is disclosed. The silicon nitride includes not more than 1% by weight of iron and reinforcements mixed and dispersed. The ceramic matrix composite material is manufactured, for example, by forming a matrix containing reaction sintered silicon carbide as the primary component and nitriding the free metal silicon produced in the sintering process so that the free metal silicon will be converted to fine silicon nitride particles. Said metal silicon used for reaction sintering already contains iron. These processes enable the containing of a comparatively large amount of reinforcements, as well as the improvement of heat resistance of the sintered compact and the suppression of the deterioration of reinforcements.

Abstract: A ceramic matrix composite material comprising a matrix containing silicon carbide as the primary component and silicon nitride as the secondary component is disclosed. The silicon nitride includes not more than 1% by weight of iron and reinforcements mixed and dispersed. The ceramic matrix composite material is manufactured, for example, by forming a matrix containing reaction sintered silicon carbide as the primary component and nitriding the free metal silicon produced in the sintering process so that the free metal silicon will be converted to fine silicon nitride particles. Said metal silicon used for reaction sintering already contains iron. These processes enable the containing of a comparatively large amount of reinforcements, as well as the improvement of heat resistance of the sintered compact and the suppression of the deterioration of reinforcements.

Abstract: A wear-resistant member consisting of ceramics containing yttrium oxide and aluminum oxide as a sintering auxiliary component and further titanium oxide, hafnium oxide and aluminum nitride, and mainly formed of silicon nitride. Silicon nitride ceramics possesses the segregation of amorphous phase mainly consisting of the sintering auxiliary component, but its size is 100 .mu.m or below at most. By restricting the segregation size of the amorphous phase to 100 .mu.m or below, sliding property, particularly rolling fatigue properties are improved. And also variability is lowered and the reliability can be highly improved.