LPPS and VPS (Vacuum Plasma Spray) are two different designations for the same process. The “flame” (no fire is actually involved in the process) is a high-temperature plasma and spraying is performed in a low-pressure argon atmosphere. This process enables materials that are sensitive to oxidation to be sprayed, these are usually the so-called MCrAlYs. The coating is very dense, and due to the absence of oxygen during spraying no oxides are formed. The surface roughness is strongly dependent on the particle size used for spraying. Normally, a relatively high degree of roughness is created and the surface will be smoothened by a shot peening and/or polishing process after coating production.
Operational costs are comparatively low as only small quantities of gas are consumed.
LPPS is the preferred metallic coating technology for single airfoil components.
It is also used for the production of metallic anti-corrosion coatings.