Abstract: A dielectric ceramic composition, which has a high dielectric constant, low loss and stable temperature characteristics suited for the microwave frequency range, is obtained by the present invention. The dielectric ceramic composition according to the present invention is expressed as (Ba.sub.x Sr.sub.1-x)(Ni.sub.1/3 Nb.sub.2/3)O.sub.3 and with a mole fraction range of 0.ltoreq.x<1.

Abstract: An improved method of manufacturing a composite structure of ceramic material reinforced by refractory fibers is disclosed, whereby the fibers are first embedded in a slip of the ceramic material containing a synthetic resin with good ceramic and fiber wetting properties and a solvent of said resin, the liquid phase is thereafter eliminated from the slip by drying, the synthetic resin is driven from the formed structure by heating, and the fiber-reinforced ceramic material is sintered. The improvement consists in avoiding the use of costly aluminum-nitride powder by initially incorporating an aluminum powder in the slip along with the resin solvent and nitriding the powder in the structure, after drying and firing, but before sintering.

Abstract: Glass fibers having suitable properties for reinforcing electrical laminates have a defined viscosity-liquidus relationship, a low coefficient of thermal expansion, a high elastic modulus, and a low dielectric constant.

Abstract: A refractory assembly for containment of molten aluminum-lithium alloys, comprising a nitride bonded silicon carbide refractory brick and a seam joined to the brick. The seam is formed from a mortar mix comprising particulate nitride refractory filler and colloidal sol binder. The brick and seam both exhibit good resistance to attack by molten aluminum-lithium alloys at elevated temperatures.

Abstract: A process for producing an aluminum nitride ceramic body having a composition defined and encompassed by polygon P1N1KJ but not including lines KJ and P1J of FIG. 4, and a thermal conductivity greater than 1.00 W/cm.multidot.K at 25.degree. C. which comprises forming a mixture comprised of aluminum nitride powder containing oxygen, yttrium oxide, and free carbon, shaping said mixture into a compact, said mixture and said compact having a composition wherein the equivalent % of yttrium and aluminum ranges between points K and P1 of FIG. 4, said compact having an equivalent % composition of Y, Al, O and N outside the composition defined and encompassed by polygon P1N1KJ of FIG.

Abstract: A process for producing an aluminum nitride ceramic body having a composition defined and encompassed by polygon FJDSR but not including line RF of FIG. 4, a porosity of less than about 10% by volume, and a thermal conductivity greater than 1.00 W/cm.multidot.K at 25.degree. C. which comprises forming a mixture comprised of aluminum nitride powder containing oxygen, yttrium oxide, and free carbon, shaping said mixture into a compact, said mixture and said compact having a composition wherein the equivalent % of yttrium and aluminum ranges from point D up to point F of FIG. 4, said compact having an equivalent % composition of Y, Al, O and N outside the composition defined and encompassed by polygon FJDSR and FIG.

Abstract: Metal vaporization from precious metals is reduced by applying to the surface of the metal a flame sprayed coating comprising a refractory material and a glass.

Abstract: A process for producing an aluminum nitride ceramic body having a composition defined and encompassed by polygon JKLM but not including line MJ of FIG. 4 and a thermal conductivity greater than 1.00 W/cm.multidot.K at 25.degree. C., preferably greater than 1.42 W/cm.multidot.K at 25.degree. C., which comprises forming a mixture comprised of aluminum nitride powder containing oxygen, yttrium oxide, and free carbon, shaping said mixture into a compact, said mixture and said compact having a composition wherein the equivalent % of yttrium and aluminum ranges from point L to less than joint J of FIG. 4, said compact having an equivalent % composition of Y, Al, O and N outside the composition defined and encompassed by polygon JKLM of FIG.

Abstract: A process for producing an aluminum nitride ceramic body having a composition defined and encompassed by polygon P1JFA4 but not including lines JF and A4F of FIG. 4, a porosity of less than about 10% by volume, and a thermal conductivity greater than 1.00 W/cm.multidot.K at 25.degree. C. which comprises forming a mixture comprised of aluminum nitride powder containing oxygen, yttrium oxide, and free carbon, shaping said mixture into a compact, said mixture and said compact having a composition wherein the equivalent % of yttrium and aluminum ranges between points J and A4 of FIG. 4, said compact having an equivalent % composition of Y, Al, O and N outside the composition defined and encompassed by polgon P1JFA4 of FIG.

Abstract: A process for producing an aluminum nitride ceramic body having a composition defined and encompassed by polygon LT1DM but not including lines LM and DM of FIG. 4, a porosity of less than about 10% by volume, and a thermal conductivity higher than 1.00 W/cm.multidot.K at 25.degree. C. which comprises forming a mixture comprised of aluminum nitride powder containing oxygen, yttrium oxide, and free carbon, shaping said mixture into a compact, said mixture and said compact having a composition wherein the equivalent % of Yttrium and aluminum ranges from point T1 up to point M of FIG. 4, said compact having an equivalent % composition of Y, Al, O and N outside the composition defined and encompassed by polygon LT1DM of FIG.

Abstract: In a method of manufacturing parts or powders made of a compound of silicon or of a metal by exothermally reacting parts or powders of silicon or a metal in the solid state with a gas, wherein the differential flow rate or the pressure variation of the reactive gas in contact with the part or the powder is sensed, and the reaction is performed at increasing temperatures as a function of the said differential flow rate or pressure of the reactive gas:the improvement wherein a maximum differential flow rate or a maximum speed of pressure drop of the reactive gas is predetermined as a function of the chemical nature of the parts or powders, and optionally as a function of the density and the size of the parts, and the rise in temperature is suspended when the differential flow rate or the speed of pressure drop of the reactive gas reaches the predetermined maximum value, beyond which the reaction would run away and prevent complete transformation of the parts or the powders being obtained.

Abstract: Enzymatic absorbent materials such as bandages and pads, for body contact applications, contain serum-activated oxidoreductase enzyme for producing hydrogen peroxide upon contact of the enzymatic materials with serum. An illustrative serum-activated oxidoreductase enzyme is glucose oxidase with the corresponding substrate in serum being glucose.

Abstract: A strong white ceramic composition and method of making the same wherein said composition is characterized by an average coefficient of thermal expansion over the range of 25.degree. C. to 500.degree. C. ("Proposed American National Standards Institute/American Dental Association Specification No. 38.1 For Porcelain-Alloy Systems") of between 14 to 16.times.10.sup.-6 /.degree.C. and a transverse strength of about 18,000 psi or even greater. The ceramic composition comprises about 40 to 60% by weight crystalline magnesium oxide particles (e.g., 74 .mu.m ) dispersed in a modified silicate glass containing at least 3% by weight of dissolved ZrO.sub.2, TiO.sub.2 or mixtures thereof and is made by firing a powdered mixture of MgO.sub.2 and modified silicate glass at about 1150.degree. C. for sufficient time to produce a fine dispersion of forsterite (Mg.sub.2 SiO.sub.4) in the continuous glass matrix phase along with the crystalline magnesia particles.

Abstract: A composition of matter, and the method of making same, suitable for in vivo implantation to provide an environment in which normal tissue growth is fostered, which composition is a porous, fibrous structure of polytetrafluoroethylene fibers and resin, wherein the combination is sintered at a temperature which fuses the fibers together without substantial detriment to their tensile strength. The composition is prepared containing a material which is soluble in a suitable solvent, which subsequent to sintering of the composition, may be removed to produce the desired amount of void space in the composition.

Abstract: Compositions of metal oxides which may be melted and cooled to produce glasses are disclosed. The glasses may be heat treated to produce glass-ceramics. The glasses have good transmittances for electromagnetic radiation in the ultraviolet, infrared and visible spectra, while the glass-ceramics have good transmittances of infrared radiation. Other physical properties make these materials desirable for purposes such as radomes.

Abstract: The sol-gel process for forming dense, alumina-base ceramics, the process comprising1. preparing a dispersion of aluminum oxide monohydrate containing a precursor of a modifying additive in the form of a soluble salt;2. gelling the dispersion;3. drying the gel dispersion to form a solid;4. calcining the solid; and5. sintering the calcined solid,is improved by adding to the dispersion at least about 10 weight percent, based on the oxide equivalent of the soluble salt precursor, of at least one densification aid selected from the group consisting of alcohols, glycols and polyether compounds having a vaporization point in excess of the temperature at which the dispersion is dried. This improved process is particularly useful for manufacturing abrasive grains.

Abstract: Method produces reaction sintered silicon nitride complex shapes. Parent material (moldings of silicon powder-cured resin) and bonding or joint material (silicon powder-uncured resin) are integrally connected by steps of heat-curing the resin in the joint, heating the body thus bonded together to pyrolyze the cured resin and sinter the silicon powder, the pyrolysis gas reducing oxide film on silicon, and sintered parent material and joint material are simultaneously nitrided and integrally connected by continuous silicon nitride.

Abstract: After sintering, ceramic body of Si.sub.3 N.sub.4 -SiC is heat-treated at 500.degree.-1500.degree. C. in atmosphere of gas mixture of chlorine and nitrogen whereby SiC is converted into silicon chloride which in turn is nitrided to form Si.sub.3 N.sub.4 in the pores of the ceramic body to provide closed pore structure. Gas mixture may contain oxygen. Heat treatment may be conducted in pressurized atmosphere of gas mixture.

Abstract: UO.sub.2 particles are brought into contact with liquid water of low pH in an oxidizing environment to dissolve uranyl hydroxide from the particle surfaces and cause more uranyl hydroxide to form and be dissolved. When sufficient uranyl hydroxide has entered the solution, the pH is raised to cause uranyl hydroxide to leave the solution and deposit on the UO.sub.2 particles. The particles are then ready for contact with an appropriate reactant to form a fugitive binder.

Abstract: What is disclosed is a method of preparing carbon-containing monolithic glassy ceramics from organosilsesquioxanes, metal oxides and metal alkoxides through pyrolysis of their gels. Also disclosed are certain gel compositions used in the method and the glassy ceramics.