Abstract: The forming of hermetic seals suitable for sealing materials having dissimilar thermal expansions which are formed by reacting an effective amount of a metal powder, selected from the group consisting of aluminum, antimony and zirconium, with glass frit having a softening point of <750.degree. C. and a coefficient of thermal expansion sufficiently compatible with the materials being sealed to yield seals characterized by a coefficient of thermal expansion closely matching or similar to those of the materials being sealed and a use temperature equal to or greater than 1000.degree. C. The seals of this invention are particularly suitable for bonding ceramic to ceramic.

Abstract: Oxygen sensor comprising solid oxygen-ion-conducting electrolyte with a platinum group metal film electrode contacts and monitors nonoxidizing or reducing gas atmosphere in a metal heat treatment (gas carburizing) furnace after a getter of the same platinum group metal as in the film electrode removes platinum group metal contaminants from such atmosphere before it contacts the electrode. Getter is held in a thin-walled, multi-passaged honeycomb body.

Abstract: The method of providing a mechanically strong, hermetic seal, for sealing glass-ceramic articles particularly MACOR.RTM. brand machinable glass-ceramics, which seal is capable of withstanding heating in a vacuum to a temperature of up to 900.degree. C. without foaming. The forming of the seal comprises reacting from 0.5-3.0 wt.% antimony metal powder with a devitrifiable glass frit having a coefficient of thermal expansion compatible with the materials being sealed and a melting point of >930.degree. C.

Abstract: A metal film electrode on the outer surface of an electroded, oxygen-ion-conducting solid electrolyte, closed end portion of an oxygen sensor tube is maintained in contact with the electrolyte and in its electrical conducting function by a compressible, porous, ceramic boot firmly press-fit onto and over the electroded end portion in slidable and frictional engagement with the outer film electrode (including any connector or reinforcing wire therein or thereon). Boot has open porosity of greater than 50 (or 80) volume percent and can consist essentially of zirconia, such as a sintered mass of zirconia fibers.

Abstract: A die assembly comprises a steel casing shrink-fitted onto and holding a ceramic die nib for extruding, drawing, ironing and the like of ferrous and nonferrous metal stock, especially in hot workable condition. The assembly includes an interlayer between the nib and casing to accommodate imperfect dimensional mating of adjacent shrink-fitted surfaces of the nib and casing. The interlayer is composed of all-crystalline ceramic material having a heating liquidus temperature within the range of 500.degree.-570.degree. C. Rigidity of solidified interlayer maintains uniform shrink-fitted compression on nib during usage of the assembly. Nib and preferred lead-zinc-borate devitrified glass interlayer are easily, jointly removable from casing and leave casing clean for reuse without affecting its case-hardening properties.

Abstract: Ceramic material, and cryogenic refrigeration apparatus containing thermal energy absorbing elements made of the ceramic material, which is a dielectric insulator and has values of specific heat at selected temperatures below 15.degree. K. that are greater than or at least equal to the values of specific heat of pure lead at those same temperatures. Material consists essentially of a crystalline phase with a composition defined by the molar formula selected from: (1) AB.sub.2 O.sub.4 where A is Group 2b metal ions with or without other divalent metal ions and B is Cr ion with or without other trivalent metal ions, (2) AB.sub.2 O.sub.6 where A is Mn and/or Ni ion(s) with or without other divalent metal ions and B is Nb and/or Ta ion(s), and (3) A.sub.2 BCO.sub.6 where A is Pb ion with or without other divalent metal ions, B is Gd or Mn with or without other trivalent metal ions and C is Nb and/or Ta ion(s). Elements include regenerator packings, thermal dampers and dielectric insulation.

Abstract: The forming of hermetic seals suitable for sealing materials having dissimilar thermal expansions which are formed by reacting an effective amount of a metal powder, selected from the group consisting of aluminum, antimony and zirconium, with glass frit having a softening point of <750.degree. C. and a coefficient of thermal expansion sufficiently compatible with the materials being sealed to yield seals characterized by a coefficient of thermal expansion closely matching or similar to those of the materials being sealed and a use temperature equal to or greater than 1000.degree. C. The seals of this invention are particularly suitable for bonding ceramic to ceramic.

Abstract: Glass-ceramic products having a manganese-containing cordierite crystal structure and being impervious void free bodies exhibiting low coefficients of thermal expansions of .about.15.times.10.sup.-7 /.degree.C. (25.degree.-1000.degree. C.) and high electrical resistivity are obtained by the sintering of glass or glass-ceramic powders having the molar composition of about 2RO.2Al.sub.2 O.sub.3.5SiO.sub.2, wherein RO is a combination of MgO and MnO.

Abstract: The addition of zirconium hydroxide to zirconia ceramic material in amounts >11 wt. % of the ceramic batch material plus hydroxide results in the development of a porous sintered zirconia-containing body for use as catalyst substrates and insulating refractories.

Abstract: A wall structure is provided for mounting an oxygen sensor probe to accurately measure the oxygen content of flowing elevated temperature atmosphere confined on one side of the wall. The sensor probe is protectively positioned and cushioned within a probe accepting bore through the wall by a flexible fibrous refractory material which thermally insulates and seals the probe within the bore from the surrounding environment. The sensing tip of the probe extends through the wall structure and is exposed to the elevated temperature combustion gases.

Abstract: Glass-ceramic products having a manganese-containing cordierite crystal structure and being impervious void free bodies exhibiting low coefficients of thermal expansions of .about.15.times.10.sup.-7 /.degree. C. (25.degree.-1000.degree. C.) and high electrical resistivity are obtained by the sintering of glass or glass-ceramic powders having the molar composition of about 2RO.2Al.sub.2 O.sub.3.5SiO.sub.2, wherein RO is a combination of MgO and MnO.

Abstract: The forming of an adherent platinum coating on the surface of hard, highly dense refractories by plasma flame spraying thereon an intermediate layer of a refractory oxide selected from the group comprised of zirconia, zircon, alumina, cordierite, mullite, or zirconia-alumina-silica having a particle size between 140 and 200 mesh, and further plasma sraying thereon a substantially 20-100 micron size platinum powder which is densified by heating to temperatures of 1350.degree.-1600.degree. C.

Abstract: Dense fused cast product and fused grain product of material whose microstructure consists essentially of at least 70 volume % chrome-containing corundum solid solution crystal phase, at least about 5 volume % oxidic secondary crystal phases mainly comprising chrome-containing alkaline earth hexaluminate solid solution, and less than 10 volume % metal phase. Analytical composition of material, by weight, consists essentially of at least 90% Al.sub.2 O.sub.3 +Cr.sub.2 O.sub.3, 20-60% Cr.sub.2 O.sub.3, 1-4% MO where M is Ca, Ba, Sr, Mg, Fe and mixtures thereof, 0.4-3.5% CaO, BaO, SrO and mixtures thereof, not greater than 3% MgO, not greater than 3.5% FeO, <5% SiO.sub.2, up to 0.5% fluorine, <1.5% R.sub.2 O wherein R is Li, Na, K, Rb, Cs and mixtures thereof, up to 2% TiO.sub.2 and up to 3% ZrO.sub.2. Resistant to corrosion by soda-lime and borosilicate glasses. Notable electrical resistivity with SiO.sub.2 <1% by weight.

Abstract: Smooth surfaces of impervious zirconia-base ceramics are chemically treated to produce micropitting and/or microcratering therein which enables durable adherence of metal coatings (e.g. of noble metal) applied thereon. Treatment involves contact of the smooth surfaces with liquid leachant selected from concentrated sulfuric acid, ammonium bisulfate, alkali metal bisulfate and mixtures thereof at a temperature of at least 250.degree. C. Leached surface is contacted with hydrochloric acid to remove reaction residue comprising sulfate of metal elements including zirconium in the ceramic.

Abstract: Honeycomb structures of brittle material having a plurality of cells extending longitudinally therethrough. When viewed in a plane perpendicular to a longitudinal axis through the structure, the plurality of cells extend thereacross and, with the exception of peripheral cells, are all of uniform size and shape. The shape is a rectangle whose length is twice its width. The cells are contiguously arranged in a repeating pattern that provides a "flexible" rectangle cellular structure wherein wall portions and joints formed by intersecting wall portions are movable to compensate for expansion/contraction stresses or forces thermally induced within the cellular structure, thereby tolerating significant strains without breaking the structure.

Abstract: A heat exchange element, particularly suitable for use as a recuperator for external combustion engines or other multiple fluid flow path body, may be produced as a monolithic, ceramic, honeycombed body having a plurality of flow paths therethrough for two or three fluids wherein multiple flow paths of separate fluids are separated by walls which may be less than 10 mils thick.The honeycombed ceramic body is provided with a plurality of open-ended cells extending from one face end to another face end and arranged in vertical columns of cells separated by vertical fluid barrier wall surfaces. Selected columns of open-ended cells are closed on both face ends of the body and entrance to and exit from the selected cells is provided by removing portions of cell walls near face ends of the body between fluid barrier wall surfaces.

Abstract: Fired refractory articles are made of a shaped refractory composition predominantly comprising grain of fusion-cast AZS refractory having: (i) a three-phase microstructure of interlocking crystals of corundum (alpha alumina) phase and baddeleyite (zirconia) phase with intercrystalline glassy phase therebetween, the glassy phase being about 15-30 vol.% of the AZS refractory, and (ii) an oxide analysis consisting of 35-60 wt.% Al.sub.2 O.sub.3 plus Cr.sub.2 O.sub.3 with Cr.sub.2 O.sub.3 .ltoreq. 60 wt.% of Al.sub.2 O.sub.3 plus Cr.sub.2 O.sub.3, 25-50 wt.% ZrO.sub.2, 10-18 wt.% SiO.sub.2, 0.8-1.8 wt.% Na.sub.2 O plus K.sub.2 O, and up to 0.7 wt.% other ingredients (e.g. impurities). Refractory composition consists of: (A) 25-60 wt.% fusion-cast AZS refractory coarse grain being at least 89 wt.% -6+20 Tyler mesh, (B) 0-38 wt.% fusion-cast AZS refractory medium grain being at least 73 wt.% -10+35 Tyler mesh, and (C) 30-50 wt.% at least one component selected from the group consisting of: (1) 0-50 wt.

Abstract: Basic fused cast refractory with principal crystal phases of periclase and magnesium-spinel is made by adding nonfused oxidic inorganic grog particles to molten mass of the refractory as it is cast into a mold cavity, thereby resulting in increased modulus of rupture at temperature in the range of about 1340.degree.-1500.degree. C. and avoidance of shell formation. Molten mass has a composition consisting essentially (by weight) of 45-78% MgO, 0-30% Cr.sub.2 O.sub.3, 0-35% Al.sub.2 O.sub.3, 0-17% FeO + Fe.sub.2 O.sub.3, at least 82% MgO + Cr.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + FeO + Fe.sub.2 O.sub.3, 1-8% SiO.sub.2, 0-2% CaO + BaO + SrO.sub.2, 0-10% TiO.sub.2 and 0-3% fluorine. Nonfused particles have a loss on ignition at 1000.degree. C. of less than about 0.5% by weight and an aggregate SiO.sub.2 content at least about equal to the SiO.sub.2 content of the molten mass forming the cast refractory. Grog particles are of a size (e.g., within the range of particles passing about 25 mm.

Abstract: An improved method of modifying a honeycombed body having a multiplicity of open-ended cells extending therethrough between opposite face ends of the body to produce therein a multiplicity of flow paths for at least two and possibly three separate fluids. For accommodating two fluids, selected columns of cells within the honeycombed body are provided with openings near at least one face end for first fluid flow through one or two longitudinal, opposed boundary surfaces and through inner cell walls parallel to the cell axes while the open-ends of such columns on a face end perpendicular to the selected cell axes are sealed against fluid flow. Second fluid flow is through the unselected columns of cells parallel to and either in the direction of or counter to the first fluid flow. Specifically, the invention provides an improved method for sealing the selected columns of cells on face ends of the body.

Abstract: A heat exchange element, particularly suitable for use as a recuperator for external combustion engines, or a body for use as an afterburner or in filtration and osmosis, may be produced as a monolithic, ceramic, honeycombed body having a plurality of flow paths therethrough for two or three fluids wherein multiple flow paths of separate fluids are separated by walls which may be less than 10 mils thick.In a preferred method, a honeycombed ceramic body is provided with a plurality of open-ended cells extending from one face end to another face end and arranged in vertical columns of cells separated by vertical fluid barrier wall surfaces. Selected columns of open-ended cells are closed on both face ends of the body and entrance to and exit from the selected cells is provided by removing portions of cell walls near face ends of the body between fluid barrier wall surfaces.