Abstract: A calcium fluoride crystal produced in accordance with a method for producing calcium fluoride crystal on the basis of refining a raw material of calcium fluoride and causing crystal growth of the refined calcium fluoride, the method including a process of raising a purity of the calcium fluoride to complement the refining, wherein a transition density in crystal is not greater than 1×105/cm2, and that dispersion of transition density inside an effective portion in crystal is in a range of ±5×104/cm2. Also disclosed is an optical element to be manufactured by use of such CaF2 crystal.

Abstract: To provide a process for recovering high quality hydrogen chloride rationally with good economical efficiency, particularly hydrogen chloride with an elevated quality level to be provided as the feedstock for the oxychlorination reaction in producing dichloroethane and a vinyl chloride monomer from a hydrogen chloride gas to be generated by the combustion of chlorine based waste. To use a process for recovering hydrogen chloride from chlorine based waste comprises adding water and a reducing agent to an acid gas obtained by the combustion of chlorine based waste to effect reaction to obtain a crude hydrogen chloride aqueous solution having an oxidation-reduction potential of not higher than 900 mV and then, distilling the crude hydrogen chloride aqueous solution to obtain a purified hydrogen chloride gas.

Abstract: Process for the conversion of sodium bromide to anhydrous hydrobromic acid and sodium bisulfate, said process with the following sequential steps: reaction of sodium bromide and sulfuric acid in a solution of water to produce hydrobromic acid and sodium bisulfate wherein the conversion rate is greater than about 95%; separation of hydrobromic acid and water from the sodium bisulfate; separation of hydrobromic acid from water; and drying of hydrobromic acid.

Abstract: A method and apparatus for removing BHP contaminants (alkali hydroxide and H2O2) from a recycled aqueous alkali chloride solution stream before the stream is fed to a chloralkali cell so that the contaminants do not impair the operation of a chloralkali cell. Unwanted alkali hydroxide within the recycled alkali chloride brine solution is reacted with chlorine gas and converted into an alkali chloride, which is useful in the operation of the chloralkali cell, and oxygen gas, which is outgassed from the system. Any H2O2 remaining in the recycled stream after elimination of the alkali hydroxide is reacted with chlorine to form HCl and oxygen gas. The HCl raises the pH of the brine solution, after which the pH may be adjusted by the addition of supplemental alkali hydroxide.

Abstract: The present invention relates to an improved method for manufacturing a crystalline layered sodium disilicate and more particularly, to the improved method for manufacturing the crystalline layered sodium disilicate comprising the steps including the preparation of granules in a certain ratio of anhydrous sodium silicate cullet, a starting material, in the presence of some binders such as water and an aqueous solution of sodium silicate, followed by a crystallization step of the granules, thus ensuring that a small amount of final product is recycled to the prior crystallization step in order to prevent the attachment of granules to an inner crystallization device, which occurs due to local sintering in a high-temperature crystallization condition of continual process and also to further enhance the unit productivity during the mass production of crystalline layered sodium disilicate.

Abstract: A method of producing a silicon carbide powder comprising sintering a mixture containing at least a silicon source and a carbon source wherein the carbon source is a xylene-based resin. Preferable are an embodiment in which the above-mentioned silicon source is an alkoxysilane compound, an embodiment in which the above-mentioned alkoxysilane compound is selected from an ethoxysilane oligomer and an ethoxysilane polymer, an embodiment in which the above-mentioned mixture is obtained by adding an acid to a silicon source, then, by adding a carbon source, and other embodiments. A silicon carbide powder produced by the above-mentioned method of producing a silicon carbide powder wherein the nitrogen content is 100 ppm or less is preferable. A sintered silicon carbide obtained by sintering the above-mentioned silicon carbide powder wherein the volume resistivity is 1×100 &OHgr;·cm or more.

Abstract: A method for producing chlorine dioxide by activating zeolite crystals (which have been impregnated with metal chlorite such as sodium chlorite, and optionally also a water-retaining substance such as magnesium sulfate, potassium chloride, potassium hydroxide, or calcium chloride) with excess protons, or activating an aqueous solution of metal chlorite and such a water-retaining substance with excess protons. Proton generating species useful for the activation are acids such as acetic, phosphoric, and citric acid, and metal salts such as ferric chloride, ferric sulfate, ZnSO4, ZnCl2, CoSO4, CoCl2, MnSO4, MnCl2, CuSO4, CuCl2, and MgSO4. The activation can be performed by causing fluid to flow through a bed of zeolite crystals impregnated with calcium chloride (or other water-retaining substance) and sodium chlorite, and a bed of zeolite crystals impregnated with a proton generating species. The two beds can be physically mixed together or the fluid can flow sequentially through separate beds.

Abstract: The golden decorative part of the present invention comprises a substrate and, formed thereon according to a dry plating process, an outermost coating, which coating comprises gold and titanium or iron together with inevitable ingredients in specific proportions. A Ti coating formed in an inert gas other than nitrogen, containing inevitable ingredients may be disposed on the substrate, and a TiN coating may be disposed on the substrate or the Ti coating. The above golden decorative part having the outermost coating containing titanium does not cause allergic dermatitis, such as contact dermatitis, even if used in contact with the skin, and exhibits a uniform golden tone. Further, the above golden decorative part having the outermost coating containing iron is strikingly less likely to cause allergic dermatitis, such as contact dermatitis, even if used in contact with the skin, and exhibits a uniform golden tone.

Abstract: An article is coated with a multi-layer coating comprising at least one nickel layer deposited on the surface of the article, a palladium/nickel alloy layer deposited on the nickel layer, a refractory metal, preferably zirconium, strike layer deposited on the palladium/nickel alloy layer, and a refractory metal compound, preferably zirconium nitride layer, deposited on the refractory metal strike layer. The coating provides the color of polished brass to the article and also provides abrasion and corrosion protection.

Abstract: The present invention relates to a novel method for forming metal matrix composite bodies and novel metal matrix composite bodies produced thereby. Particularly, a polycrystalline oxidation reaction product of a parent metal and an oxidant is first formed. The polycrystalline oxidation reaction product is thereafter comminuted into an appropriately sized filler material which can be placed into a suitable container or formed into a preform. The filler material or preform of comminuted polycrystalline oxidation reaction product is thereafter placed into contact with a matrix metal alloy in the presence of an infiltration enhancer, and/or an infiltration enhancer precursor and/or an infiltrating atmosphere, at least at some point during the process, whereupon the matrix metal alloy spontaneously infiltrates the filler material or preform. As a result of utilizing comminuted or crushed polycrystalline oxidation reaction product, enhanced infiltration (e.g., enhanced rate or amount) is achieved.

Abstract: A binder for binding reinforcement materials is provided in which an aluminum and/or Group IIa-containing compound is combined, in a liquid, with a phosphorus-containing compound wherein said binder has a ratio of phosphorus to aluminum and/or Group IIa ions of 14 to 34, preferably 20 to 30. The binder is useful in binding reinforcement materials, particularly suited for preparing preforms for making metal matrix composite materials.

Abstract: The invention relates to a composite body in which a ceramic component and a metal component are bonded to one another by internal soldering. The internal soldering is effected with soldering composition in a recess (2) within a component (1) of the one material in which there is arranged a component (3) of the other material which is shaped to fit accurately. The recess (2) is, at at least one end-face opening, surrounded by a chamfer (5) having an angle .phi. smaller than 35.degree. C., while the wetting angle .beta. between the soldering composition and the plane of the component surface in which the recess is located is smaller than 40.degree..

Abstract: A zinc-base galvanized sheet steel which comprises zinc-base plated sheet steel and, formed on the plating layer surface, an inorganic covering layer which contains at least one inorganic oxide in an amount of 1-500 mg/m.sup.2 in terms of the weight of metallic elements exclusive of oxygen and optionally contains at least one oxoacid or inorganic oxide colloid in an amount of 1-500 mg/m.sup.2 and further, as desired for improving weldability, a Zn oxide film formed between the inorganic covering layer and the zinc-base plating layer, and the process for producing said galvanized sheet steel.

Abstract: Processes for preparing a relatively concentrated aqueous solution of about 700-3000 ppm hyprobromous acid are provided. Hypochlorous acid solutions are prepared by either reacting chlorine gas with water or sodium hypochlorite with an acid. The resulting hypochlorous acid is then reacted with an alkali metal or alkaline earth bromide in order to form the hypobromous acid. Critical parameters are pH, Br/Cl mole ratio, and chlorine concentration. Under optimum conditions, substantially 100% conversion of bromide to hypobromous acid can be attained.

Abstract: In a process for producing anhydrous magnesium chloride, the following combination of steps: drying impure salt containing hydrated magnesium chloride; establishing a solution of the hydrated magnesium chloride; removing insoluble impurities; reacting the solution of hydrated magnesium chloride at substantially ambient temperature and pressure by feeding it into an ammonia saturated very low boiling point alcohol solution and in the presence of ammonium chloride while maintaining the last-mentioned solution saturated in ammonia thereby to form a precipitate of ammoniated magnesium chloride; separating the precipitate and heating it to obtain anhydrous MgCl.sub.2 and ammonia for recycling.

Abstract: A thermal barrier coating for superalloy turbine engine vanes and blades that are exposed to high temperature gas is disclosed. The coating includes a ceramic layer applied to an Aluminide or MCrAlY bond coat by electron beam physical vapor deposition. The ceramic layer has a first portion having unstabilized porosity, a second portion, overlying the first portion, with stabilized porosity, and an outer portion wherein the pores are coated with a noble metal. The stabilized porosity portion along with the noble metal coating reduce the thermal conductivity of the ceramic layer. Stabilizing the porosity renders it more resistant to sintering densification at high temperatures.

Abstract: A potassium chloride mixture with grains of different sizes is extracted in a first stage with an unsaturated solution at an elevated temperature, whereby the finest grains are completely dissolved and the coarse proportions are caused to start dissolution, the purified medium fraction is transported into a second process stage and the previously dissolved amount of KCl is crystallized there onto the purified grains at a lower temperature, forming a product of high purity with a balanced grain size and a narrow grain spectrum.

Abstract: The invention relates to a process of producing chlorine dioxide using, in a first alternative atmospheric pressure and hydrogen peroxide in the reaction medium optionally with an electrolytic cell. In a second alternative, either atmospheric or subatmospheric pressure is used in the reaction medium together with an organic or inorganic reducing agent and an electrolytic cell.

Abstract: An article is coated with a multilayer coating comprising a nickel-tungsten-boron alloy layer deposited on the surface of the article, a refractory metal, preferably zirconium, strike layer deposited on the nickel-tungsten-boron alloy layer, and a refractory metal compound, preferably zirconium nitride, deposited on the refractory metal strike layer. The coating provides the color of polished brass to the article and also provides abrasion protection.

Abstract: A rotary seal member, such as a gas turbine engine blade, is provided with an improved surface layer which has an elastic modulus matched with the elastic modulus of a substrate of the member. Also, the surface layer does not form a brittle intermetallic with the substrate at an intended operating temperature. In one form, the surface layer includes abrasive particles adapted to inhibit chemical reaction with the layer material. One specific example is a Ti-alloy substrate having a metallurgically bonded layer based on Nb, and including cubic boron nitride abrasive particles coated with cobalt entrapped in the layer.