Abstract: Glass ceramic comprising apatite crystals and at least 50% by weight of wollastonite crystals and a process for producing the same are disclosed. The glass ceramic contains from 45 to 56% by weight of CaO, from 1 to less than 10% by weight of P.sub.2 O.sub.5, from 30 to 50% by weight of SiO.sub.2, from 0 to 5% by weight in total of one or two of MgO and Y.sub.2 O.sub.3, and from 0 to 5% by weight of one or more of F.sub.2, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, Al.sub.2 O.sub.3, TiO.sub.2, ZrO.sub.2, SrO, Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5, with the total content of CaO, P.sub.2 O.sub.5 and SiO.sub.2 being at least 90% by weight. The glass ceramic exhibits excellent biocompatibility and has improved strength.

Abstract: A continuous inorganic fiber consisting of Si, N and O has excellent physical, chemical and electrically insulating properties, is superior to carbon fiber in wettability with metal, is low in reactivity with metal, and can be used not only as a reinforcing fiber for fiber-reinforcing type metals and fiber-reinforcing type ceramics, but also in electrical insulating materials and in heat-resistant materials.

Abstract: A ceramic composition for dielectrics, consisting essentially of an inorganic dielectric material including at least one electrically insulating glass and at least one organic binder, and further comprising at least one inorganic peroxide. The inorganic peroxide serves to facilitate burnout or removal of the organic binder during firing of the ceramic composition and minimizes the content of residual carbon in the fired ceramic composition. The inorganic peroxide is preferably selected from the group consisting of calcium peroxide, strontium peroxide, barium peroxide, zinc peroxide and cadmium peroxide, and present preferably in an amount of 0.1-40% by weight. Also disclosed is a process of manufacturing a ceramic circuit board using the ceramic composition stated above.

Abstract: The invention relates to halide-containing glass. Glass with anionic conductivity for fluorine comprises PbO, F, and a glass-forming agent. As the glass-forming agent boron oxide (B.sub.2 O.sub.3) is used, with the following proportions of the components, per cent by mass:PbO: 86.0 to 87.0F: 3.5 to 0.5B.sub.2 O.sub.3 : 10.5 to 12.5Glass with anionic conductivity for fluorine is intended, mainly, for making dividers of electric signals.

Abstract: A high chromia refractory composite has been developed with improved thermal shock resistance and containing about 5-30 wt. % of unstabilized ZrO.sub.2 having a temperature-dependent phase change resulting in large expansion mismatch between the ZrO.sub.2 and the chromia matrix which causes microcracks to form during cooling in the high chromia matrix. The particle size preferably is primarily between about 0.6-5 microns and particularly below about 3 microns with an average size in the order of 1.2-1.8 microns.

Abstract: Low concentration standard aqueous solution for analytical purposes is prepared from a water soluble glass body containing the standardizing material. The glasses are phosphorus pentoxide based glasses and provide release rates, e.g. of Na.sup.++, of 0.01 to 100 micrograms per cm.sup.2 per hour.

Abstract: A process for producing a composition which includes a perovskite compound, the process comprising:(a) subjecting a mixture of a hydroxide of at least one A group element selected from the group consisting of Mg, Ca, Sr, Ba, Pb and rare earth elements and a hydroxide of at least one B group element selected from the group consisting of Ti, Zr, Hf and Sn, to the hydrothermal reaction in an aqueous reaction medium;(b) adding an insolubilizing agent to the resultant reaction mixture to insolubilize water-soluble compounds of the unreacted A group element dissolved in the aqueous medium so as to adjust the ratio of the group A element to the group B element in a resulting composition to a desired A/B ratio; or(c) filtering, washing with water and drying the resultant reaction mixture to provide a solid reaction product, dispersing the reaction product in an aqueous medium to form a slurry, adding to the slurry a water-soluble compound of the A group element, and then adding to the slurry an insolubilizing agent t

Abstract: A composition having a low dielectric constant and low dielectric loss tangent from room temperature to at least about 1100.degree. C. comprises a silicon nitride based material containing an effective amount of a sintering aid and an effective amount of a low dielectric loss promoter.

Abstract: A composite nitride sintered body consisting essentially of aluminum nitride, boron nitride and at least one metal compound selected from the group consisting of compounds of metals of Groups IIa and IIIa of the periodic table.The composite nitride sintered body is produced by intimately mixing a powder of aluminum nitride, a powder of boron nitride and at least one metal compound selected from the group consisting of metal compounds of metals of Groups IIa and IIIa of the periodic table, and sintering the mixture under atmospheric or elevated pressures at a temperature in the range of 1600.degree. to 2400.degree. C.The sintered body has a good machinability.

Abstract: A method and an apparatus for avoiding or reducing the interactions and their consequences from contact of hot liquid metals with concrete. At least for the region of the concrete structure near the surfaces which may come into contact with the hot liquid metal, there is employed a concrete containing aluminum oxide, magnesium oxide, zirconium oxide, or a mixture thereof, in a proportion of 70% by weight to 96.5% by weight.

Abstract: Silicon nitride sintered bodies having particularly excellent strength and creep resistance at high temperature, in which a total amount of MgO and Al.sub.2 O.sub.3 is more than 7% by weight and not more than 30% by weight and a weight ratio of MgO/Al.sub.2 O.sub.3 is 5-15 and the remainder is mainly Si.sub.3 N.sub.4 and at least one of magnesium sialon crystal represented by the general formula Mg.sub.x/2 Si.sub.6-y+x/2 Al.sub.y-x O.sub.y N.sub.8-y (0<x.ltoreq.y<8, preferably 0.9.ltoreq.x/y) and forsterite crystal represented by the formula Mg.sub.2 SiO.sub.4 is contained as a second phase in addition to the main crystal of Si.sub.3 N.sub.4, are produced by mixing a raw material powder of silicon nitride containing not greater than 2% by weight of oxygen with MgO and Al.sub.2 O.sub.3 so that a total amount of MgO and Al.sub.2 O.sub.3 is from 7% by weight to 30% by weight and a weight ratio of MgO/Al.sub.2 O.sub.3 is 5-15, and firing the resulting mixture at a temperature of 1,650.degree.-1,850.degree.

Abstract: A mixture of alumino-silicate glass and alumina having a composition corresponding to mullite and containing a nucleating mullite powder is hot pressed producing a dense polycrystalline mullite body having an average grain size of less than 15 microns.

Abstract: Improved Si.sub.3 N.sub.4 /ZrO.sub.2 composite ceramics are described, having low thermal conductivity and which are substantially free of surface spalling and material degradation. Such composites are produced by incorporating an additive, e.g. MgO, CaO or Y.sub.2 O.sub.3, preferably Y.sub.2 O.sub.3, in suitable molar proporations based on ZrO.sub.2, and sintering the mixture with Si.sub.3 N.sub.4. In a preferred embodiment a powder mixture of 70% Si.sub.3 N.sub.4 and 30% ZrO.sub.2, by volume, and containing 6.6 mole percent Y.sub.2 O.sub.3 based on ZrO.sub.2, is formed and is sintered to produce a composite ceramic. The Y.sub.2 O.sub.3 is preferably pre-reacted with the ZrO.sub.2 to form a solid solution. A sintering aid, preferably Al.sub.2 O.sub.3, e.g. in an amount of about 2 to about 4%, by weight of the total mixture, can be added to permit production of the Si.sub.3 N.sub.4 /ZrO.sub.2 composite by pressureless sintering.

Abstract: A low expansion glass comprising, all by weight, from 55 to 65% of SiO.sub.2, from 10 to 20% of Al.sub.2 O.sub.3, from 2 to 10% of B.sub.2 O.sub.3, from 3 to 10% of MgO, from 1 to 8% of CaO, from 2 to 10% of ZnO, from 0 to 4% of R.sub.2 O where R is an alkali metal atom, and from 0 to 4% of ZrO.sub.2.

Abstract: Aluminous proppant media in the form of sintered bauxite spheres containing silica are improved in resistance to stress corrosion by inclusion of zirconia in the mix prior to firing in the amount of a silica to zirconia ratio of from 6/1 to 20/1.

Abstract: A ceramic composition particularly useful for use in thin film magnetic heads, the composition having the general formula:xNaO.yNb.sub.2 O.sub.5wherein the ratio x/y is at least 0.74 but less than 1.00, the composition having a coefficient of thermal expansion closely matching that of the magnetic alloy film with which it is used so as to prevent separation of the two upon changes in temperature.

Abstract: A sintered material based on silicon nitride for use in preparing cutting tools is provided. This material is prepared by sintering a mixture of silicon nitride containing 2-10 percent by weight of yttrium oxide, 1-5 percent by weight of aluminium oxide and 10-40 percent by weight of titanium carbide coated with titanium nitride under hot pressing or sintering followed by hot isostatic pressing at an elevated temperature ranging from 1600.degree. C. to 1800.degree. C. The coated titanium carbide in the form of powder can be formed by depositing a film of titanium nitride on the surface of titanium carbide in the presence of gaseous titanium tetrachloride, hydrogen and nitrogen under the partial pressure of 0.1 to 0.5 atmosphere at 1000.degree. C. to 1500.degree. C. The material can endow the cutting tools with higher toughness and strength and longer life.

Abstract: An article is disclosed which is made of silicon nitride based material consisting essentially of in percent by weight about 6% yttrium oxide and the balance silicon nitride. The article has open porosity of from about 37% by volume at which level the strength of the article is about 15 ksi to about 10% by volume open porosity at which level the strength of the article is about 72 ksi.The article can have within its open porosity a lubricating material.

Abstract: Disclosed is a sintered ceramic body having a composition comprising (i) Si.sub.3 N.sub.4, (ii) a combination of an oxide of an element of the group IIIa of the Periodic Table having an ionic radius smaller than 0.97 .ANG. and an oxide of other element of the group IIIa of the Periodic Table, having an ionic radius larger than 0.97.degree. and (iii) an oxide or nitride of at least one of the following: (1) at least one element of group IIa of the Periodic Table; (2) Al; (3) Ti; (4) Cr; (5) Ga; (6) Zr; and (7) Si. This sintered silicon nitride body shows a high oxidation resistance when it is used for a long time at high temperatures, and the sintered body is excellent in the creep characteristics and flexural strength at high temperatures.

Abstract: A ceramic body of zirconium dioxide containing, if desired, aluminum oxide, nd partially stabilized with yttrium oxide and/or one or more rare earth oxides (e.g., cerium dioxide) and/or magnesium oxide and/or calcium oxide is partially stabilized with 0.5 to 5 mole-% of yttrium oxide and/or 5 to 12 mole-% of magnesium oxide and/or calcium oxide and/or cerium dioxide or one or more rare earth oxides, is 30 to 100% in the tetragonal lattice modification and has in the surface region a content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide that is 1 to 20 mole-% higher than the average content, such that the body is coated with a thin, PSZ-like layer in a more highly stabilized tetragonal or with a layer that is predominantly in the cubic lattice form.