Abstract: The calciner is an elongated, insulated chamber, in which material is fed to counter-rotating screw conveyors. The material is calcined by heat radiating from a muffle plate interposed between the conveyors and gas-fired burners. This radiant heating, applied evenly to material having a constantly-exposed fresh surface, results in increased production, lower fuel cost per pound of product, and higher quality product.

Abstract: A unique sintering method of developing a controlled porosity, controlled thickness, metal layer on a metal substrate is disclosed. The region to be coated is cleaned, a suitable adhesive applied and appropriate metal powder poured on. Additional layers of adhesive and powder can be applied to give desired thickness. Pore size is determined by the size and shape of the powder particles and by the degree of sintering selected. Controlled sintering of the particles is carried out at a temperature near the melting point of the metal in a hydrogen atmosphere to permanently attach the particles to the substrate. The sintering is only sufficient to bond the particles while avoiding over-sintering which would close the porosity.No foreign material is left, the adhesive being burned off during sintering. The porous surface thus produced provides secure anchorage for the ingrowth of body tissue in a prosthetic device such as a heart valve or bone implant.