Abstract: Microcrystalline boehmite suitable for conversion to anhydrous alumina products is produced by hydrothermal treatment of precursor alumina raw material at controlled pH and in the presence of microcrystalline boehmite seed material. Reaction mix may include submicron seed material for seedling for later conversion of the microcrystalline boehmite to alpha alumina. Removal of metal cations by ion exchange is employed when high purity product is required. Other materials may be added to reaction mix. Production of alumina products, catalysts, and ceramic bodies is disclosed.

Abstract: Seeding of beta type alumina compositions in which the alumina in the raw batch is microcrystalline boehmite results in significant increase in hardness, density and strength, as compared to unseeded beta alumina, when fired under similar conditions.

Abstract: Straight and arcuately curved superheater tube shields of refractory material comprising a pair of elongated half shields of identical interchangeable interfitting and interlocking size and shape, each half shield having a semicircular sidewall of corresponding straight or arcuate shape of predetermined radius of curvature extending between opposite ends and to inner diametrically opposite inner sides lying in a central plane and the plane of curvature. A number of mating camming portions with inclined camming surfaces are precisely spaced adjacent each of the inner sides so that one of the half shields may be turned end for end relative to and assembled to the other about a correspondingly shaped superheater tube by a relatively short axial movement and engagement of the inclined camming surfaces whereby the half shields are pulled together to close the joints therebetween and interlocked about the superheater tube. A refractory cement may be applied to attach the half shields to the tubes.

Abstract: Zirconia ceramics containing substantial amounts of metastable tetragonal phase crystallites, so that they are tougher than most other ceramics, can be completely comminuted to powders, without applying any mechanical force, by treatment with water or steam at temperatures well above room temperature. This type of comminution is particularly useful for small, often hollow, spheres produced by rapidly solidifying melts of zirconia and a stabilizing oxide such as yttria. These spheres can be almost completely comminuted to a size suitable for wet vibratory milling by treatment for twenty-four hours at 250 C under sufficient steam pressure to maintain some liquid water in equilibrium.

Abstract: A cement for vessels for containing molten alloys of aluminum with metals selected from the group consisting of lithium, magnesium, zinc and copper is shown that forms a hard sintered crust for containing the molten alloy in the vessel with a backing of granular cement for controlling thermal stress while also providing a vitrifying flux means in the cement mix for effecting a sealing of any cracks that may form in the crust by reacting with any hot alloy flowing through such a crack to contain the leak as a metal spur.

Abstract: A combination of materials is disclosed which imparts superior fire retardant properties to organic polymers and the gaseous by-products of those polymers. The combination is made up of an organo phosphate plasticizer, aluminum hydroxide or alumina hydrate, antimony trioxide, a borate, a brominated hydrocarbon and a chlorinated paraffin.

Abstract: A diffusion furnace component system is disclosed which includes a liner, process tube, paddle and boat. These various elements are made up of a matrix of sintered silicon carbide which has been infiltrated with 5 to 30% by weight of silicon metal and finally coated with an impervious film or layer of a high purity refractory material such as e.g. silicon carbide.

Abstract: The burner block or tile in industrial furnaces is conventionally made of refractory ceramic material. Such refractories are susceptible to cracking from thermal shock if the temperature of the burner block fluctuates during use. The life of the burner block can be greatly improved by making it in two parts: a cavity bounding inner part made from a material more shock resistant than a conventional refractory and a conventional refractory outer part. Best results are obtained with a thin inner liner of recrystallized silicon carbide having a thermal conductivity of over 18 W/(m K) and a modulus of rupture of at least 120 MPa.

Abstract: A support device for supporting a packing material in a packed column having an upwardly flowing gas and a downwardly flowing liquid. The device comprises a plate having a plurality of formations. Each formation comprises spaced side walls connected by an upper wall, with apertures being provided in the side walls to permit the flow of the gas therethrough. A collecting channel is provided on at least one of the formations to collect the downwardly flowing liquid. The formations have a plural-skin construction to reduce the amount of liquid flowing through the apertures. The formations are provided with streamlining in order to improve the efficiency of gas flow.

Abstract: A combination of fused alumina grits with sintered gel alumina abrasive grits is shown to be more effective than either abrasive alone in cutting steel bars with bonded abrasive wheels at intermediate cutting speeds.

Abstract: Diisopropyl ethers of oligomers of ethylene glycol having between 2 and 8 ethylene glycol moieties and an average molecular weight between 190 and 300, are more useful physical absorption solvents for the separation of acid gases than are dimethyl, diethyl, ethyl butyl, propyl butyl, dibutyl, or higher alkyl ethers of the same ethylene glycol oligomers, because of a combination of high solution capacity, high separation efficiencies, low viscosity, low gas pressure, and resistance to hydrolysis during use. The diisopropyl ether of diethylene glycol is especially advantageous for use at absorber temperatures below 0.degree. C. Because of low viscosity, the diisopropyl ethers can often be substituted in separation equipment designed for use with chemical rather than physical solvents, thereby realizing the lower operating costs associated with physical solvents without requiring new capital investment.

Abstract: An efficient embossed packing element for exchange columns is made up of a plurality of preformed embossed vertical sheets, each having a plurality of elongated inclined troughs including converging embossed sidewalls, valleys, and ridges extending between upper inlet edges and lower outlet drip edges and projecting alternately outwardly from one side and then the opposite side of the median plane of each sheet. Projecting from the converging sidewalls of the troughs are a plurality of hollow protuberances with perforated peaks including small openings surrounded by edges of the wall about the peaks.

Abstract: A catalyst for the selective reduction of nitrogen oxides to nitrogen in the presence of ammonia in the form of composite bodies formed from a mixture of zirconia (5 to 50% by weight), a zeolite (50 to 90%), a bond material (0 to 30%), and, optionally, a promoter selected from oxides of vanadium and copper in the amount of at least 0.1% by weight.

Abstract: A rotary joint for establishing supply and removal connections for flow of a working fluid between stationary external piping and the interior of a rotating drum, the joint including a stationary tubular shaft assembly about which a flanged housing is rotatably journaled, wherein a heat exchange chamber system is formed interiorly within the shaft assembly annularly thereabout and along the housing journals with a baffle within the chamber system for causing a heat exchange fluid to circulate throughout the annular and longitudinal extent of the chamber system thereby relieving the housing journals from any opposed heat exchange effects of the working fluid to enable high speed operation of the rotary joint at either relatively high or low temperatures.

Abstract: A catalyst for the selective reduction of nitrogen oxides to nitrogen in the presence of ammonia in the form of composite bodies formed from a mixture of anatase (5 to 40% by weight), a zeolite (50 to 90%), a bond material (0 to 30%, and, optionally, promoter selected from oxides of vanadium, molybdenum, and copper, in the amount of at least 0.1% by weight.

Abstract: A process for purifying crude silicon carbide lumps from an Acheson furnace comprising agitating the lumps in a drum having a cylindrical wall, its axis substantially horizontal and having openings of controlled size, smaller than said crude lumps, in said cylindrical wall, separating the particles passing through said controlled size openings according to size and recirculating oversize particles back to said rotating drum and finally recovering product retained in said drum.

Abstract: Flexible coated abrasives with facile straight tear in either the length or cross directions can be made on stitch bonded fabric backings having (1) an aral density between 51 and 153 gm/m.sup.2, (2) a tensile strength in the length direction between 5.4 and 12.6 kN/m of width, (3) a tensile strength in the cross direction which is between 5.4 and 11.7 kN/m of length and is between 0.9 and 1.35 times as great as the length direction tensile strength, (4) an elongation to break in the length direction of not more than 40%, and (5) an elongation to break in the cross direction of not more than 35%. The fabric is prepared for coating by saturation with at least its own weight of a finishing adhesive composed primarily of latices of acrylic homopolymers, acrylic copolymers, butadienestyrene polymers, or mixtures of these types.

Abstract: A refractory batt for supporting green ceramic or refractory ware during firing thereof, wherein said batt includes a groove or recess diagonally oriented in each quadrant, with the bottom of the recess or depression merging smoothly at the ends into the upper surface of the batt and spaced from the center and corner. The depth of the recess in each quadrant is not more than two thirds the thickness of the batt.

Abstract: Stitch bonded fabrics were found to be suitable substrates for coated abrasives when the fabric has a strength in the warp direction of at least 30 dekanewtons (daN) per centimeter (cm) of width, a fill yarn cover factor of at least 40%, and stitch yarns with a tensile strength of at least 0.5 daN. For substitution of the established commercial classes of abrasives known as X and Y weights, the fabrics are preferably made on a Malimo machine, with 14-22 warp yarns of 840-1300 denier high tenacity multifilament polyester or glass per 25 cm of fabric width, at least 64 fill yarns of staple or texturized multifilament polyester per 25 cm of fabric length, and stitch yarns of 70-140 denier high tenacity multifilament polyester.

Abstract: A continuous process for casting a molten metal oxide such as an aluminous oxide and more particularly an alumina-zirconia eutectic composition that is subsequently crushed to produce an abrasive is provided wherein two thin metal belts are brought into face-to-face relation and the molten oxide is poured into the nip between the belts as they come into face-to-face relation. The material that is being solidified maintains the belts slightly spaced apart on the order of some small fraction of an inch (e.g. 1/16) and the back surface of the belt is flooded with copious quantities of cooling fluid (e.g. water) to maintain the belts below red heat. The belts are held in closely spaced relation for a sufficient time to permit the abrasive to be cooled below red heat. The belts are then separated and the abrasive is discharged from between the belts.