ATMOSPHERES FOR HEAT TREATING NON-FERROUS METALS AND ALLOYS

摘要

A process for producing low-cost atmospheres suitable for annealing, brazing, and sintering non-ferrous metals and alloys from non-cryogenically produced nitrogen containing up to 5% residual oxygen is disclosed. According to the process, suitable atmospheres are produced by 1) pre-heating the non-cryogenically produced nitrogen stream containing residual oxygen to a desired temperature, 2) mixing it with more than a stoichiometric amount a hydrocarbon gas, 3) passing it through a reactor packed with a platinum group of metal catalyst to reduce the residual oxygen to very low levels and convert it to a mixture of moisture and carbon dioxide, and 4) using the reactor effluent stream for annealing, brazing, and sintering non-ferrous metals and alloys in a furnace. The key features of the disclosed process include 1) pre-heating the non-cryogenically produced nitrogen containing residual oxygen to a certain minimum temperature, 2) adding more than a stoichiometric amount of a hydrocarbon gas to the pre-heated nitrogen stream, and 3) using a platinum group of metal catalyst to initiate and sustain the reaction between oxygen and the hydrocarbon gas.