Abstract: Disclosed is a spray concrete which, even at a water-cement ratio of 0.45 to 0.55, is still easy to work, can be sprayed well, and sets and hardens rapidly. It contains, in addition to the conventional additives, additions of naphthalinesulfonicacid-formaldehyde condensation products and highly concentrated alkaline aqueous solutions of potassium aluminate, potassium carbonate and caustic potash. The concrete according to the invention displays an especially rapid solidification when it contains up to 3% by weight alkali silicates or an adequate amount in highly dispersed silicic acid (SiO.sub.2). The additives are incorporated into the concrete preferably directly at the worksite prior to spraying.

Abstract: Reduced boron containing glass fibers are provided which have a refractive index similar to that of higher boron-containing glass fiber compositions. The glass fibers with a refractive index in the range of greater than 1.5495 to around 1.57 have in weight percent SiO.sub.2 - 55-56.5, CaO - 20-23, Al.sub.2 O.sub.3 14.5-15.5, B.sub.2 O.sub.3 - 5 to 5.8, R.sub.2 O - 1-1.5, wherein R is an alkali metal and F.sub.2 - 0.4 to 0.6. In addition, the glass fiber composition can have minor constituents such as TiO.sub.2 of up to around 0.6 weight percent and an MgO of up to around 0.3 weight percent and ferric oxide of up to around 0.3 weight percent. Basically, the glass fibers have a reduced content of both B.sub.2 O.sub.3 and CaO over standard glass fiber compositions such as E-glass and 621-glass and also has elevated amounts of alkali and of refractory constituents such as SiO.sub.2 and Al.sub.2 O.sub.3. The glass fibers are formed with an elevated temperature of 40.degree. to 50.degree. F. (22.degree.-28.degree.

Abstract: A type I dielectric composition based on neodymium titanate is formed of a mixture comprising 58% to 78% by weight of neodymium titanate (Nd.sub.2 O.sub.3 -3TiO.sub.2), 10 to 21% by weight of lead titanate (PbTiO.sub.3), 5% to 14% by weight of barium titanate (BaTiO.sub.3), 4% to 15% by weight of barium zirconate (BaZrO.sub.3) and 0.2% to 1.2% by weight of yttrium oxide (Y.sub.2 O.sub.3).

Abstract: A polycrystalline body having a composition comprised of Y.sub.2-x Sr.sub.x O.sub.3-x/2 wherein x ranges from about 0.0015 to about 0.012.

Abstract: A crystallized glass-ceramic molded product having a glass matrix and crystallized calcium fluoride and fluormica dispersed therein. The molded product is prepared by mixing and melting together the necessary constituents for forming the glass, calcium fluoride and fluormica and rapidly cooling the melt to produce a frit. Particles of the frit or of two or more frits are then subjected to sintering and crystallizing heat treatments.

Abstract: An aluminum nitride-based sintered body having a high thermal conductivity and a total oxygen content of 0.01 to 20% by weight which is prepared by mixing a main component of aluminum nitride powder containing 0.001 to 7% by weight of oxygen with 0.01 to 15% by weight of at least one of the group consisting of a powder of a rare earth element and/or a powder of a material containing the rare earth element (said 0.01 to 15% by weight being counted on the basis of the content of the rare earth element), and sintering said powder mixture.

Abstract: A process for producing an aluminum nitride ceramic body having a composition defined and encompassed by polygon ABCDEFGH excluding line DE of FIG. 2, a porosity of less than about 10% by volume, and a thermal conductivity greater than 0.70 W/cm.multidot.K at 25.degree. C. which comprises forming a mixture comprised of aluminum nitride powder containing oxygen, an Ln oxide selected from the group consisting essentially of erbium oxide, holmium oxide, a mixture and solid solution thereof, and free carbon, shaping said mixture into a compact, said mixture and compact having a composition wherein the equivalent % of Ln and aluminum ranges from point A up to point E of FIG. 2, said mixture and said compact having an equivalent % composition of Ln, Al, O and N outside the composition defined and encompassed by polygon ABCDEFGH of FIG.

Abstract: A method of converting particles liberated in chemical or physical processes, such as fly ash, metal processing sludge particles obtained in the preparation of metals or metal compound, or particles of electroplating sludge, are made harmless by preheating these particles to at least 600.degree. C. and then mixing same with a molten slag material, whereafter the mixture is solidified and broken.Preferably, the particles are preheating to their softening point or are molten.Noxious products, such as metals, being present in said particles cannot be leached out from the broken solidifed composition.

Abstract: An improved lead calcium titanate piezoelectric sintered body is produced by sintering in air at 1000.degree. C.-1200.degree. C. a calcined mixture of oxides or oxide compounds in amounts adapted to form a composition of the formula Pb.sub.1-x Ca.sub.x Ti.sub.1-y (Co.sub.1/2 W.sub.1/2).sub.y O.sub.3 +0.005-0.02(A) where A is at least one of MnO, MnO.sub.2, NiO and Nb.sub.2 O.sub.3, wherein x=0.3-0.4 and 0.04<y.ltoreq.0.06.

Abstract: An improved process for producing a translucent polycrystalline alumina body comprising sintering a prefired compacted green body of alumina of predetermined shape is disclosed. The green body of alumina includes alumina doped with one or more sintering aids. The method of the present invention comprises sintering the prefired compacted green body of predetermined shape at a maximum sintering temperature in an atmosphere containing nitrogen and an amount of hydrogen greater than or equal to about 2.5 volume percent and less than 75 volume percent for a period of time sufficient to produce a translucent polycrystalline alumina body.

Abstract: A piezoelectric ceramic composition is disclosed wherein a sintered body having a bismuth layer structure represented by a molecular formula of PbBi.sub.4 Ti.sub.4 O.sub.15 contains 10 to 55 mol % of an oxide of Ca and Ti, namely CaTiO.sub.3, or 1 to 15 mol % of an oxide of Sr and Ti, namely, SrTiO.sub.3. The bismuth layer structure of PbBi.sub.4 Ti.sub.4 O.sub.15 has a positive dielectric-constant-temperature characteristic, and CaTiO.sub.3 or SrTiO.sub.3 is obtained by sintering as an added substance exhibiting a negative dielectric-constant-temperature characteristic. Since the added substance is added to the piezoelectric ceramic composition so that the temperature changes in both dielectric constants are mutually cancelled out, thereby maintaining the piezoelectric constants at a substantially fixed level.

Abstract: A fine powder of neodymium titanate or barium neodymium titanate, a process for its preparation and applications in ceramic compositions. A suspension of particles is formed by mixing a solution of neodymium nitrate or a solution of barium and neodymium nitrates with a sol of titania having a pH of from about 0.8 to 2.5 which contains elementary crystallites of TiO.sub.2 having a size of from about 10 to about 100 .ANG. in diameter which are agglomerated into submicron masses of from about 200 to about 1,000 .ANG. in diameter. The suspension obtained is dried, and the dried product is calcined at a temperature between 800.degree. C. and 1,300.degree. C., preferably for about 1 to 24 hours. If necessary, the powder obtained is milled. The fine powder obtained has a low fritting temperature and its density after heating for 2 hours at 1,300.degree. C. is greater than or equal to 95% of the theoretical density of the desired titanate powder.

Abstract: A sinterable yttrium oxide powder is produced useful for pressureless sintering a compact thereof into an optically translucent or transparent body. The yttrium oxide powder has a specified particle size range and specific surface area. It is formed by preparing yttrium oxalate hydrate powder by means of the wet chemical oxalate method, comminuting the yttrium oxalate hydrate powder to a required degree and calcining the yttrium oxalate hydrate.

Abstract: A dielectric ceramic composition consists essentially of a main component composed of a solid solution of a three component system Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 -Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 -PbTiO.sub.3, characterized in that said main component consists essentially of 68.05 to 69.60 wt % of Pb.sub.3 O.sub.4, 2.41 to 4.00 wt % of MgO, 0.08 to 3.15 wt % of ZnO, 24.01 to 26.66 wt % of Nb.sub.2 O.sub.5, and 0.13 to 2.59 wt % of TiO.sub.2, and has a set of compositional proportions of the three components falling within an area defined by a polygon ABCD encompassed by points A, B, C, and D in FIG. 1, and that a subsidiary component consisting essentially of MgO is incorporated into said main component in an amount of not more than 1.0 part by weight (except 0 part by weight) with respect to 100 part by weight of the main component. The composition may further contain, as a part of the subsidiary component, manganese and/or a compound represented by the general formula: A(Cu.sub.1/2 W.sub.1/2)O.sub.

Abstract: The present invention relates to a two-part gunning refractory composition wherein fine powders of a refractory aggregate and superfine refractory powders are previously made into the form of a slurry containing therein a deflocculant, thereby reducing the amount of aluminous cement and also reducing the amount of water to achieve a deposit applied by gunning having a quality comparable to one produced by casting.

Abstract: Disclosed is a sintered body of a composition comprising (i) 80 to 99% by weight of Si.sub.3 N.sub.4, (ii) 1 to 20% by weight of oxides, nitrides and the like of Sr, W and a rare earth element as the main additive and (iii) an oxide, a nitride or the like of Al, Ti, Cr, Si or Mo as the auxiliary additive in an amount of up to 5 parts by weight per 100 parts by weight of the components (i) and (ii). This sintered body is excellent in oxidation resistance and mechanical strength at high temperatures.

Abstract: A porous ceramic filter consisting of a planar porous support formed of a ceramic material, and a filtering layer formed of a fired mass of a ceramic powder integrally deposited on an upper surface of the porous ceramic support. A particle size of the ceramic powder, and a size of macro pores formed in the fired mass of said ceramic powder, decrease substantially continuously in a direction from the upper surface of the ceramic support toward an exposed surface of the filtering layer.

Abstract: A process for treating a halide, e.g. fluoride, glass composition, characterized by contacting a melt of the composition with dry oxygen. Oxygen, simply on contact with a fluoride glass melt, converts transition metals, e.g. from Fe(II) to Fe(III), from one stable state to another and thereby reduces loss at transmission wavelengths in optical fiber, e.g. the loss at 2.7 .mu.m attributable to Fe(II).

Abstract: A low-temperature sinterable ceramic composition comprising 1 to 20% by weight of Al.sub.2 O.sub.3, 15 to 50% by weight of SiO.sub.2, 0 to 5% by weight of MgO, 3 to 18% by weight of CaO, 0 to 5% by weight of TiO.sub.2, 1 to 8% by weight of B.sub.2 O.sub.3, 0 to 2% by weight of Li.sub.2 O, 20 to 80% by weight of at least one of zircon, mullite and spinnel, and 1 to 12% by weight of a fluoride selected from CaF.sub.2, MgF.sub.2, LiF, AlF.sub.3, MnF.sub.2, BaF.sub.2 and SrF.sub.2.

Abstract: Alumina fibers whose surface is coated with zirconia to retain their identity in an alumina matrix when the mixture is sintered at temperatures needed to form a fully dense ceramic. The resulting fully dense ceramic composite shows the beneficial effects of such reinforcing fibers by having increased crack toughness.