Z. Zurecki, Air Products & Chemicals, Inc., Allentown, PA
Activation or an in-situ (in-furnace) formation of heat treating atmospheres has been a subject of continuous interest for holding a promise of significant operating, capital, time, and energy savings. To date, various types of low-pressure (ion) plasma, in-furnace catalyst, and direct gas injection methods have been successful in selected applications. This paper is an R&D update concerning a new, universal system for activating and/or in-situ forming of processing atmospheres which may be used in carburizing, nitriding, brazing, bright annealing and other treatments carried out in 1-atm-pressure as well as vacuum furnaces. The operation of the system, involving electric excitation and in-line reactions of gas streams injected into conventional furnace, will be illustrated by the example of carburizing steel in a highly diluted, non-flammable, and non-oxidizing natural gas atmosphere such as N2-2.5vol% CH4.
Summary: The work reported in this presentation focuses on forming of reactive treatment atmospheres at the furnace injection point. A new system for in-line activation of atmosphere gases is described which enables effective operations with highly diluted hydrocarbon and/or ammonia gases at the conventional temperatures. Raman spectroscopy of effluent gas stream and metallographic analysis of exposed steels illustrate experimental carburizing treatments. Scaling up of the new atmosphere activation system to the mid- and large-sized industrial furnaces is in progress.
