US Patent 9970095 Ion assisted deposition top coat of rare-earth oxide

A method of manufacturing an article comprises providing an article. An ion assisted deposition (IAD) process is performed to deposit a second protective layer over a first protective layer. The second protective layer is a plasma resistant rare earth oxide having a thickness of less than 50 microns and a porosity of less than 1%. The second protective layer seals a plurality of cracks and pores of the first protective layer.