Heat treating atmospheres.

摘要

A process for producing low-cost atmospheres suitable for annealing, brazing, and sintering ferrous and non-ferrous metals and alloys, neutral hardening low, medium, and high carbon steels, sintering ceramic powders, and sealing glass to metal 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) introducing the reactor effluent stream into the heating zone of a furnace and converting in-situ a portion of both moisture and carbon dioxide with a hydrocarbon gas to a mixture of carbon monoxide and hydrogen. 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, 3) using a platinum group of metal catalyst to initiate and sustain the reaction between oxygen and the hydrocarbon gas, and 4) converting in-situ a portion of both moisture and carbon dioxide with a hydrocarbon gas to a mixture of carbon monoxide and hydrogen in the heating zone of a furnace.