Abstract
The plasma transferred arc process continues to be the coating method of choice for the application of cobalt base alloys onto valve and valve trim. Although new applications have been developed over the years, the process remains largely associated with the application of high performance, highly alloyed powders for relatively small parts or small areas of large parts. The use of the plasma transferred arc process for large volume application has been limited by the robustness and performance characteristics of the equipment and the use of cobalt. A new plasma transferred arc system (power source, torch and process controller) has been developed which allows the application of powder metal alloys at deposition rates of up to 40 pounds per hour. In addition, there has been a development of new non-cobalt powder alloys with excellent mixed corrosion and wear resistance properties. These capabilities have rendered the process technically and economically viable for large and demanding applications in the mining, power utility and steel industries. The new PTA system and the recent developments in powder alloys will be discussed. Reference will be made to specific applications in target industries.
