Abstract: A method for making a composite ceramic article by infiltration of a sintered ceramic preform with an infiltrate phase. The ceramic preform is made by directionally solidifying a liquid medium containing a dispersion of ceramic particles to produce a green, porous ceramic preform a plurality of interconnected lamelli that are partially separated from one another by complementary interlamellar regions, removing the solidified liquid medium and sintering the ceramic preform. This method may be used to make silicon carbide composites where a silicon carbide preform is first infiltrated with carbon to coat the lamelli of the preform, followed by infiltration of the carbon coated preform with molten silicon, whereby the molten silicon and carbon react to form silicon carbide in the interlamellar regions.

Abstract: A composite is comprised of reinforcement fibers having a continuous coating with a first layer of a metal oxide wherein the metal is from the group consisting of aluminum, yttrium, titanium, zirconium, beryllium, silicon, and the rare earths, and a molten silicon infiltration formed silicon carbide matrix. The coating may have a second layer from the group consisting of rhodium, iridium, metal carbide, metal silicide, metal nitride, and metal diboride, on the metal oxide coating. The reinforcement fibers being fibers from the group consisting of elemental carbon, silicon carbide, and mixtures thereof. A process for producing the fiber reinforced composite comprises depositing on the fibers a continuous coating comprised of the first layer of the metal oxide, and the second layer. A carbonaceous material is admixed with the coated fibers so that at least 5 volume percent of the mixture is the fibers.

Abstract: A protective coating for a reinforcement phase exposed to molten silicon or silicon alloy infiltrant comprises, an inner layer material resistant to reaction with the molten infiltrant, an interlayer of a reactive material that reacts with the infiltrant to form compounds having a melting temperature greater than the infiltrant, and an outer layer material resistant to reaction with the molten infiltrant. Materials resistant to reaction with molten silicon are a metal carbide from the group consisting of carbides of titanium, hafnium, zirconium, and tantalum; a metal nitride from the group consisting of nitrides of boron, silicon, aluminum, titanium, zirconium, hafnium, niobium, and tantalum; a metal boride from the group consisting of borides of titanium, zirconium, hafnium, silicon, and aluminum, or combinations thereof.

Abstract: An alloy having a very high resistance to oxidation is taught. The alloy contains between 30 and 75 atom percent of silicon in an iridium base. The alloy may be used in the form of a surface coating to protect structural elements of other materials from oxidation. The alloy may also be used as an ingredient of a composite.

Abstract: Coatings that provide substantial oxidation protection for titanium substrates are comprised of a continuous coating of ductile MCrAl or ductile MCr alloys where M is at least one metal selected from the group consisting of iron, nickel, and cobalt. Ductile MCrAl alloys are comprised of, by weight percent: about 10 to 40 percent chromium, about 4 to 10 percent aluminum, and the balance substanitally iron; about 8 to 40 percent chromium, about 4 to 10 percent aluminum, and the balance substantially nickel; or about 10 to 25 percent chromium, about 4 to 5.5 percent aluminum, and the balance substantially cobalt. Ductile MCr alloys are comprised of, by weight percent: about 20 to 40 percent chromium, and the balance substantially iron; about 20 to 50 percent chromium, and the balance substantially nickel; or about 15 to 35 percent chromium, and the balance substantially cobalt.

Abstract: A composite is produced comprised of ceramic oxide fibrous material which is coated with a noble metal and disposed in a ceramic oxide matrix. The composite can be produced by contacting the coated fibrous material with matrix-forming oxide powder to form a compact and densifying the compact. Densification can be carried out by techniques such as sintering, isostatic pressing, and hot pressing. The composite can also be produced by forming the coated fibrous material into a preform having an open porosity and infiltrating the preform with a vapor of the matrix-forming material.

Abstract: A composite is produced comprised of ceramic oxide fibrous material which is coated with a noble metal and disposed in a polycrystalline ceramic oxide matrix.

Abstract: High pressure sodium lamps have been subject to progressive reduction in pressure of contained sodium with attendant reduction in lighting quality. It has now been discovered that modification of lamp components permits the pressure of contained sodium to be maintained at higher levels. Emission materials enclosed within the lamp are altered to limit reactive oxygen in the lamp atmosphere. A thermionic electrode is equipped with an improved emission mix composition containing an oxide selected from the group consisting of tungsten, molybdenum and yttrium. The emission mix also contains the metal of the respective oxide in finely divided form.

Abstract: High pressure sodium lamps have been subject to progressive reduction in pressure of contained sodium with attendant reduction in lighting quality. It has now been discovered that modification of lamp components permits the pressure of contained sodium to be maintained at higher levels. Emission materials enclosed within the lamp are altered to limit reactive oxygen in the lamp atmosphere. A thermionic electrode is equipped with an improved emission mix composition as illustrated in areas A and B of the triaxial plot of FIG. 3 and an oxygen getter is intermixed with the mix composition. The oxygen getter is a metal which forms a highly stable oxide and may be at least one selected from the group consisting of titanium, zirconium, hafnium, tantalum and yttrium.

Abstract: High pressure sodium lamps have been subject to progressive reduction in pressure of contained sodium with attendant reduction in lighting quality. It has been discovered that modification of lamp components permits the pressure of contained sodium to be maintained at higher levels. Emission materials enclosed within the lamp are altered to limit reactive oxygen in the lamp atmosphere. A thermionic electrode as equipped with an improved emission composition as illustrated in areas B and C of the triaxial plot of FIG. 3.

Abstract: A method is described for effecting the removal of alkali metal contaminants from a super heated gaseous mixture useful in power generation. Finely divided refractory oxide particles are introduced into the hot gaseous mixture without effecting a substantial reduction in the temperature and operating efficiency of the system. The alkali metal contaminants are substantially removed from the hot gaseous mixture by being adsorbed onto the surface of the finely divided refractory oxide particles.