LPPS-Thin Film Process; Overview of Origin and Future Possibilities

The original paper on the LPPS process was presented in London in 1973 by Erich Muehlberger. This paper described the “Low Pressure Plasma System” as a plasma process taking place in a vacuum chamber providing a controlled atmosphere of both pressure and gas content. The process used widely in spraying MCrAlys typically takes place in an argon environment at a pressure of 20 -50 millibar. Around 20 years following that original paper experiments were conducted at Electro-Plasma  to produce a different condition at a lower pressure of close to 2 millibars. The original objective was to produce a larger and faster plasma stream to allow more efficient coating of large surfaces. The process can produce coatings at a much faster rate (1 micron, m²/sec) and that approach those produced by the EB-PVD process in both thickness and structure. The unique feature of using a plasma stream as a carrier media gives the process some significant advantages over other processes. This paper describes some of the original goals of the process and some of the possible future applications.