A method to form a machinable ceramic matrix composite comprises forming a porous ceramic multilayer on a surface of a fiber preform. In one example, the porous ceramic multilayer comprises a gradient in porosity in a direction normal to the surface. In another example, the porous ceramic multilayer includes low-wettability particles having a high contact angle with molten silicon, where an amount of the low-wettability particles in the porous ceramic multilayer varies in a direction normal to the surface. After forming the porous ceramic multilayer, the fiber preform is infiltrated with a melt, and the melt is cooled to form a ceramic matrix composite with a surface coating thereon. An outer portion of the surface coating is more readily machinable than an inner portion of the surface coating. The outer portion of the surface coating is machined to form a ceramic matrix composite having a machined surface with a predetermined surface finish and/or dimensional tolerance.

Described herein is a gaslight multilayered composite tube having a heat transfer coefficient of >500 W/m.sup.2/K which in its construction over the cross section of the wall of the composite tube includes as an inner layer a nonporous monolithic oxide ceramic surrounded by an outer layer of oxidic fiber composite ceramic, where this outer layer has an open porosity of 5%<ε<50%, and which on the inner surface of the composite tube includes a plurality of depressions oriented towards the outer wall of the composite tube. Also described herein is a method of using the multilayered composite tube as a reaction tube for endothermic reactions, jet tubes, flame tubes or rotary tubes.

A light generator comprises a light conversion device and a light source arranged to apply a light beam to the light conversion element. The light conversion device includes an optoceramic or other solid phosphor element comprising one or more phosphors embedded in a ceramic, glass, or other host, a metal heat sink, and a solder bond attaching the optoceramic phosphor element to the metal heat sink. The optoceramic phosphor element does not undergo cracking in response to the light source applying a light beam of beam energy effective to heat the optoceramic phosphor element to the phosphor quenching point.

A process for manufacturing a fibrous preform filled with particles, includes forming the filled preform by compacting a stack of a plurality of fibrous strata impregnated by a suspension of ceramic oxide particles in a liquid medium, wherein the liquid medium includes at least one compound having a saturated vapor pressure of less than 2.3 kPa at 20° C., this compound being present in a weight content of greater than or equal to 30% relative to the total weight of the suspension.

A light generator comprises a light conversion device and a light source arranged to apply a light beam to the light conversion element. The light conversion device includes an optoceramic or other solid phosphor element comprising one or more phosphors embedded in a ceramic, glass, or other host, a metal heat sink, and a solder bond attaching the optoceramic phosphor element to the metal heat sink. The optoceramic phosphor element does not undergo cracking in response to the light source applying a light beam of beam energy effective to heat the optoceramic phosphor element to the phosphor quenching point.

The present invention relates to inorganic fibres having a composition comprising: 65.7 to 70.8 wt % SiO.sub.2; 27.0 to 34.2 wt % CaO; 0.10 to 2.0 wt % MgO; and optional other components providing the balance up to 100 wt %,
wherein the sum of SiO.sub.2 and CaO is greater than or equal to 97.8 wt %; and the other components, when present, comprise no more than 0.80 wt % Al.sub.2O.sub.3; and wherein the amount of MgO and other components are configured to inhibit the formation of surface crystallite grains upon heat treatment at 1100° C. for 24 hours, wherein said surface crystallite grains comprise an average crystallite size in a range of from 0.0 to 0.90 μm.

Provided is a silicate glass, a method for preparing a silicate glass-ceramics by using the silicate glass, and a method for preparing a lithium disilicate glass-ceramics by using the silicate glass, and more particularly, to a method for preparing a glass-ceramics that has a nanosize of 0.2 to 0.5 μm and contains lithium disilicate and silicate crystalline phases. A nano lithium disilicate glass-ceramics containing a SiO.sub.2 crystalline phase includes: a glass composition including 70 to 85 wt % SiO.sub.2, 10 to 13 wt % Li.sub.2O, 3 to 7 wt % P.sub.2O.sub.5 working as a nuclei formation agent, 0 to 5 wt % Al.sub.2O.sub.3 for increasing a glass transition temperature and a softening point and enhancing chemical durability of glass, 0 to 2 wt % ZrO.sub.2, 0.5 to 3 wt % CaO for increasing a thermal expansion coefficient of the glass, 0.5 to 3 wt % Na.sub.2O, 0.5 to 3 wt % K.sub.2O, and 1 to 2 wt % colorants, and 0 to 2.0 wt % mixture of MgO, ZnO, F, and La.sub.2O.sub.3.

A ceramic bonding material including at least one fibrous material, a flux agent and a thickening agent wherein the ceramic bonding material fired at a set temperature to bond the two adjacent substrate faces.

A process for the manufacture of inorganic fibres comprises: (a) selecting a composition and proportion of: (i) silica sand; (ii) lime comprising at least 0.10 wt % magnesia; and (iii) optional additives comprising a source of oxides or non-oxides of one or more of the lanthanides series of elements, or combinations thereof; (b) mixing the silica sand; lime; and optional additives to form a mixture; (c) melting the mixture in a furnace; and (d) shaping the molten mixture into inorganic fibres. The raw materials selection comprises composition selection and proportion selection of the raw materials to obtain an inorganic fibre composition comprising a range of from 61.0 wt % and 70.8 wt % silica; less than 2.0 wt % magnesia; less than 2.0% incidental impurities; and no more than 2.0 wt % of metal oxides and/or metal non-oxides derived from said optional additives; with calcia providing the balance up to 100 wt %; and wherein the inorganic fibre composition comprises no more than 0.80 wt % Al.sub.20.sub.3 derived from the incidental impurities and/or the optional additives.

Provided is a silicate glass, a method for preparing a silicate glass-ceramics by using the silicate glass, and a method for preparing a lithium disilicate glass-ceramics by using the silicate glass, and more particularly, to a method for preparing a glass-ceramics that has a nanosize of 0.2 to 0.5 μm and contains lithium disilicate and silicate crystalline phases. A nano lithium disilicate glass-ceramics containing a SiO.sub.2 crystalline phase includes: a glass composition including 70 to 85 wt % SiO.sub.2, 10 to 13 wt % Li.sub.2O, 3 to 7 wt % P.sub.2O.sub.5 working as a nuclei formation agent, 0 to 5 wt % Al.sub.2O.sub.3 for increasing a glass transition temperature and a softening point and enhancing chemical durability of glass, 0 to 2 wt % ZrO.sub.2, 0.5 to 3 wt % CaO for increasing a thermal expansion coefficient of the glass, 0.5 to 3 wt % Na.sub.2O, 0.5 to 3 wt % K.sub.2O, and 1 to 2 wt % colorants, and 0 to 2.0 wt % mixture of MgO, ZnO, F, and La.sub.2O.sub.3.