Abstract: An infrared cold shield comprises a side wall, a top wall and at least one baffle extending across the interior of the cold shield. The top wall and baffles comprise aligned apertures. The cold shield is preferably made by securing one or more metal foil disks and aluminum mandrel segments in an alternating stacked arrangement wherein the outer edges of the metal foil disks are exposed. The assembly is then electroplated to deposit a layer of metal over the side surfaces of the mandrel segments and to capture and bond with the exposed edges of the metal foil sections. The mandrel segments are then dissolved.

Abstract: An infrared cold shield comprises a side wall, a top wall and at least one baffle extending across the interior of the cold shield. The top wall and baffles comprise aligned apertures. The cold shield is preferably made by securing one or more metal foil disks and aluminum mandrel segments in an alternating stacked arrangement wherein the outer edges of the metal foil disks are exposed. The assembly is then electroplated to deposit a layer of metal over the side surfaces of the mandrel segments and to capture and bond with the exposed edges of the metal foil sections. The mandrel segments are then dissolved.

Abstract: A wear insert for earth boring tools, such as drill bits, has diamonds imbedded in a sintered matrix of tungsten-carbide and Invar. The matrix prior to sintering has a particle size of from about 0.5 to about 10 microns. Invar represents from about 3% to about 20% by weight of the matrix. The diamonds are arrayed in a desired pattern in a matrix preform; compression of the resultant preform at pressures of from about 10 to about 20 tons per square inch consolidates preform. The consolidated preform is sintered at a temperature just below the melting point of Invar in a neutral atmosphere of nitrogen and hydrogen formed of dissociated ammonia. Nitrogen results in the wetting of the diamonds. Hydrogen presents a reducing atmosphere.

Abstract: A wear insert for earth boring tools, such as drill bits, has diamonds imbedded in a sintered matrix of tungsten-carbide and Invar. The matrix prior to sintering has a particle size of from about 0.5 to about 10 microns. Invar represents from about 3% to about 20% by weight of the matrix. The diamonds are arrayed in a desired pattern in a matrix preform; compression of the resultant preform at pressures of from about 10 to about 20 tons per square inch consolidates preform. The consolidated preform is sintered at a temperature just below the melting point of Invar in a neutral atmosphere of nitrogen and hydrogen formed of dissociated ammonia. Nitrogen results in the wetting of the diamonds. Hydrogen presents a reducing atmosphere.