Pusher Tubes For Refractory Metal Powder Reduction

One of the processing steps employed in the production and processing of refractory metal powders like molybdenum, tungsten as well as rhenium from their ores is the reduction of oxides using hydrogen. This step is usually carried out at high temperatures using a reducing furnace consisting of pusher tubes, which serve as a containment or muffle for the boats comprising the powder to be reduced. Additionally, indirectly fired rotary kilns are also employed in the processing. The high temperature process necessitates the usage of heat resistant alloys for components like the rotary kilns, pusher tubes and boats. Material property requirements are essentially a combination of creep strength and oxidation resistance. Heat resistant Centralloy(R) alloys of S+C with austenitic matrix and strengthened by strong carbide formers are most suited for these demanding applications. With these high performance alloys application temperatures of up to 1175degC are possible.