A method for forming a plasma resistant ceramic coating on an article includes placing the article into a chamber or spray cell of a plasma spraying system. A ceramic powder is then fed into the plasma spraying system at a powder feed rate, and a plasma resistant ceramic coating is deposited onto at least one surface of the article in a plasma spray process by the plasma spray system. The plasma spray system is then used to perform an in-situ plasma flame heat treatment of the plasma resistant ceramic coating to form crust on the plasma resistant ceramic coating.