Abstract: A method of controlling chosen geometries in sintering operations uses an insert in the preform which is to be sintered, which insert can withstand sintering temperatures without distortion, and which will not bond to the preform and thus prevent removal subsequent to sintering. In powder metal sintering, inexpensive ceramic alumina inserts satisfy these criteria. A powdered metal preform is caused to shrink onto a precisely formed ceramic insert, thereby to determine final shape accurately. An insert larger in diameter than that of the uninserted undistorted preform final diameter may be used if potential impact on geometry density is factored into its selection. An insert shape other than that of the preform undistorted final shape may be used to create final geometries different by design than those of the preform.

Abstract: A method of producing self-supporting ceramic bodies having a modified metal-containing component includes first providing a self-supporting ceramic body comprising (i) a polycrystalline oxidation reaction product formed upon oxidation of a molten parent metal precursor with an oxidant, and (ii) an interconnected metal-containing component at least partially accessible from one or more surfaces of said ceramic body. The surface or surfaces of the ceramic body is contacted with a quantity of foreign metal different from said interconnected metal-containing component at a temperature and for a time sufficient to allow for interdiffusion, whereby at least a portion of said metal-containing component is displaced by said foreign metal. The resulting ceramic body, having an altered metal-containing component, exhibits modified or improved properties.

Abstract: There is disclosed a reinforcing mat for use in the production of a ferro-cement structure. The mat comprises outer layers of spaced rods or wires having further layers of wire mesh therebetween. The rods or wires of the outer layers are welded together at their crossing points to secure the further layers therebetween.

Abstract: A continuous process for making rigid PVC foam objects by extruding a preform from an initial PVC mixture, optionally cutting the preform into blanks, and expanding the preform or the blanks in water heated to a temperature above 70.degree. C. The initial mixture contains polyvinyl chloride, at least a first blowing agent capable of generating a gas, for example an isocyanate or a polyisocyanate, and at least one organic anhydride (and does not contain any added inert particles finely divided therein). The initial mixture may also contain less than one weight percent of a second blowing agent, for example azobisisobutyronitrile or azodicarbonamide. The objects produced possess heat- and sound-insulating properties.

Abstract: A process for manufacturing polyurethane-coated products is disclosed. These polyurethane-coated products are manufactured by press-forming a metal material coated with a lubricant inclusive of a compound having an oxygen-hydrogen bond into a core member of a desired shape and covering necessary portions of the core member a with polyurethane foam or coating formed by reacting the compound with an isocyanate of the polyurethane forming material without degreasing steps, i.e. pretreatments for washing off the lubricant.

Abstract: A cellular polymeric resin sheet, slab or the like is produced by filling a pressure resistant receptacle having a cover directly releasably locked thereto with a uniform mixture of a resin such as polyvinyl chloride, a finely divided heat activated first gas generator and preferably a water activated second gas generator together with other additives such as plasticizers, stabilizers, etc. The closed receptacle is heated to effect the gelation and fusion of the resin and the activation of the first gas generator to produce a high density uniform small pore cellular resin body embryo under high pressure in the receptacle. The receptacle and embryo are cooled, the receptacle opened and the embryo removed and subjected to a high humidity atmosphere, preferably at elevated temperature to activate the second gas generator and react therewith.

Abstract: An expandable vinyl chloride resin composition for foaming under atmospheric pressure which comprises a resin ingredient comprising (A) a vinyl chloride homopolymer or copolymer having substantially no active hydrogens, (B) a vinyl chloride copolymer having active hydrogens and (C) a thermoplastic polyurethane resin, and a crosslinking agent, a foaming agent, a thermal stabilizer and a plasticizer, the ratio of the components (A), (B) and (C) being 30 to 90:5 to 40:5 to 40 by weight. The composition is expanded under atmospheric pressure to give a foam of a high expansion ratio which has uniform and fine cells and shows an excellent rubber-like elasticity.

Abstract: An improved process and apparatus for producing rigid cellular materials comprising polyvinyl chloride, wherein the controlled expansion of embryonic blocks obtained by molding, is carried out in a single expansion box closed throughout the whole duration of the expansion treatment, in several stages including pre-heating, pre-expanding and final expansion to the final dimensions of the block, the expansion box containing the block expanded to its final dimensions being then immersed in a bath of cold water for dimensional stabilization.The expansion box comprises at least two plates, with a frame attached to the lower face of each plate, to form, in use, a closed expansion box which is provided with a centering and holding mechanism to maintain the embryonic block in place within the expansion box, a device for opening and closing the expansion box being also provided, as well as a mechanism for transferring a plurality of expansion boxes assembled together from one bath to the other in succession.