Union Carbide Corporation

Jack Solomon

Raymond P Roberge

Mark S Nowotarski

Arthur W Francis

Thomas F Kinneman

This invention relates to a process for substantially reducing the backmixing or backflow of gases into metal heat treating furnaces by the use of a particular gas jet and a defined flow rate.

Process for reducing backmixing

In a process for carburizing steel parts, wherein it is desired to shut down the carburizing process for a predetermined period of time without removing the parts, the improvement comprising the following steps:

Process for carburizing steel

In a process for carburizing steel in a furnace, using a defined carburizing atmosphere and regulating in defined manner the hydrocarbon component according to the amount of carbon dioxide present; maintaining a high flow rate when the passage through which the steel passes is open and a low flow rate when it is closed; and closing all other passages through which gas can pass.

In a process for sintering powder metal parts comprising: (a) passing the parts through a furnace adapted therefor from its upstream end to its downstream end, said furnace having two successive zones, an upstream zone, which is maintained at a temperature in the range of about 800.degree. F to about 2200.degree. F and a cooling zone, said furnace further having an atmosphere therein comprising carbon monoxide, hydrogen, carbon dioxide, water and nitrogen distributed throughout the zones; (b) permitting the parts to reside in the upstream zone for a sufficient length of time to cause sintering; and (c) removing the sintered parts from the furnace, the improvement comprising: introducing a mixture consisting essentially Of methanol and nitrogen into the upstream zone at a point where a temperature of at least about 1500.degree. F is maintaied, the methanol and nitrogen being in a ratio sufficient to provide, when subjected to such temperature, an atmosphere comprising, in percent by volume, about 1 to about 20 percent carbon monoxide; and about 1 to about 40 percent hydrogen; and balance nitrogen.

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Rye, NY, United States of America

Jack Solomon