Components such as showerheads, focus rings, and liners in plasma etch chambers are exposed to fluorine- and chlorine-based plasmas and ion bombardment. Thermally sprayed ceramic coatings protect the underlying aluminum alloys. Particle emission from coating spallation is often more critical than the erosion rate itself, because it limits wafer yield and chamber lifetime.

Yttria (Y₂O₃) is the reference material for fluorine plasmas, since it forms a fluoride or oxyfluoride surface layer that slows further erosion. Alumina (Al₂O₃) is less expensive but generally erodes faster. Atmospheric plasma spraying produces lamellar coatings with open porosity and microcracks, which can allow gas penetration and delamination. Suspension HVOF spraying yields denser, finer microstructures and is a promissing aproach.