METHODS FOR FORMING PROTECTIVE COATINGS CONTAINING CRYSTALLIZED ALUMINUM OXIDE

Embodiments of the present disclosure generally relate to protective coatings on substrates and methods for depositing the protective coatings. In one or more embodiments, a method of forming a protective coating on a substrate includes depositing a chromium oxide layer containing amorphous chromium oxide on a surface of the substrate during a first vapor deposition process and heating the substrate containing the chromium oxide layer comprising the amorphous chromium oxide to convert at least a portion of the amorphous chromium oxide to crystalline chromium oxide during a first annealing process. The method also includes depositing an aluminum oxide layer containing amorphous aluminum oxide on the chromium oxide layer during a second vapor deposition process and heating the substrate containing the aluminum oxide layer disposed on the chromium oxide layer to convert at least a portion of the amorphous aluminum oxide to crystalline aluminum oxide during a second annealing process.