Study on compact α-Al₂O₃ coating fabricated by sol-gel method

Transparent and stable alumina sol have been prepared by sol-gel method using aluminum isopropoxide as precursor, water as solvent and nitric acid as peptizer. Heat-treatment is adopted for the formation of Al₂O₃ coatings after the alumina gel is plated by liquid-falling method. Then transformation from alumina gel to Al₂O₃ is studied by TG-DTA. The result of XRD shows that the obtained coatings have crystal structure of α-Al₂O₃ and SEM shows that α-Al₂O₃ coatings finely combined with substrate are compact, homogeneous and crackfree. So the method is a good and simple one in fabricating compact a-Al₂O₃ coatings.