Method of forming plasma-resistant coating layer with low brightness using heat treatment process of rare-earth metal compound powder

A method of forming a plasma-resistant coating layer, the method comprising:

• (a) performing a heat treatment process in a temperature range of 1,200° C. to 1,400° C. on a primary rare-earth metal compound powder having a grain size in a range of 20 nm to 60 nm to prepare a secondary rare-earth metal compound powder;
• (b) transferring the secondary rare-earth metal compound powder from a powder supply device to a deposition chamber;
• and
• (c) spraying the transferred secondary rare-earth metal compound powder onto a substrate to form a rare-earth metal compound coating layer on the substrate,
• wherein the primary rare-earth metal compound powder and the secondary rare-earth metal compound powders are selected from the group comprising yttria (Y2O3), yttrium fluoride (YF), or yttrium oxyfluoride (YOF),
• wherein in the transferring, a carrier gas is supplied to transfer the secondary rare-earth metal compound powder,
• wherein the secondary rare-earth metal compound powder obtained through the heat treatment process has a grain size in a range of 90 nm to 150 nm,
• wherein in the spraying, the substrate is selected from metal comprising iron, magnesium, aluminum, or alloys thereof;
• ceramic material comprising SiO2, MgO, CaCO3, or alumina;
• or
• polymeric material comprising polyethylene terephthalate, polyethylene naphthalate, polypropylene adipate, or polyisocyanate, and
• wherein the rare-earth metal compound coating layer has a brightness value of 50 or less.