Abstract: Method for removing tar-forming hydrocarbons from an effluent gas mixtures from Chemical Vapor Deposition or Chemical Vapor Infiltration processes. Method includes passing at elevated temperature effluent gas mixture containing hydrogen, methane, and high molecular weight hydrocarbons through a bed that contains iron pellets, thereby decomposing tar-forming high molecular weight hydrocarbons in the effluent gas mixture. Apparatus including a de-tarring vessel (5) having a packed bed (7, 8, 9) of iron or iron oxide pellets (1) resting over a perforated distributor plate (2) and having an exhaust port (12), said de-tarring vessel being operatively linked via an exhaust port (6) to a CVI or CVD reactor vessel.

Abstract: There is provided a method for producing a self-supporting ceramic composite comprising (1) a ceramic matrix obtained by oxidation of an aluminum zinc alloy to form a polycrystalline oxidation reaction product of the metal with an oxidant, and (2) one or more fillers embedded by the matrix. The metal alloy and permeable mass of filler having at least one defined surface boundary are oriented relative to each other so that formation of the oxidation reaction product will occur into said mass of filler and in a direction towards said defined surface boundary. On heating the metal to a first temperature above its melting point but below the melting point of said oxidation reaction product to form a body of molten parent metal, the molten metal reacts with said oxidant to form said oxidation reaction product which infiltrates said mass of filler to said defined surface boundary.

Abstract: A method for economically removing base metal impurities, other oxidizable impurities, and volatile impurities from precious-metal-bearing metallic materials, consisting of silver and gold, to obtain, with high recovery, a resultant precious metal of high purity (more than 99.9%) that greatly reduces refining time and precious metal loss in recovery. The method includes the steps of (1) controlled heating to maintain a temperature slightly above the melting temperature of the molten metallic mass, (2) maintaining contact between an oxidizing agent and the metallic mass to provide a concentration of dissolved oxygen within the molten metal throughout the refining process, (3) maintaining a flux medium on the surface of the molten material that absorbs base metal and other impurity oxides, and (4) controlling the concentration of base metal and other impurity oxides in the flux to a level that ensures continued transfer of the base metal oxides into the flux medium.