Braze Signature in Brazing With Atmospheric Pressure Microwave Plasma

Automotive parts have been brazed by heating with atmospheric pressure plasma generated by a computer controlled 2.45 GHz, 5 kW microwave source. The plasma is created in a suitable gas by a simple, proprietary ignition process and is confined to the vicinity of the joint, thereby eliminating thermal stress in other areas. Brazing of 1008 low-carbon steel parts with copper generates a distinctive spike in the plasma emission intensity at the time when copper melts. This spike can be used as a signature for brazing. The energy efficiency, test results, and the significance of the braze signature are discussed.