C-Al2O3 coatings prepared by cathode plasma electrolytic deposition on TC4 substrate for better high temperature oxidation resistance

• Published in: Surface & coatings technology Vol. 405; p. 126585
• Main Authors: Zhang, Shuguang, Zhao, Chao, Zhang, Jin, Lian, Yong, He, Yedong
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.01.2021; Elsevier BV
• Subjects: Aluminum oxide; C-Al2O3 coatings; Carbon; Cathode plasma electrolytic deposition; Cathodes; Cathodic coating (process); Coatings; Decrease porosity; Doping; Electrical resistivity; Electrodeposition; Electrolytes; First principles; Glycerol; High temperature; High temperature oxidation resistance; Oxidation; Oxidation resistance; Oxidation tests; Porosity; Substrates; X ray photoelectron spectroscopy; Cathode plasma electrolytic deposition; Glycerol; High temperature oxidation resistance; Decrease porosity; C-Al2O3 coatings
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2020.126585

The Al2O3 coating prepared by cathode plasma electrolytic deposition (CPED) method usually has porous structure, which is not conductive to its application in the field of high temperature oxidation resistance. In this paper, carbon doped Al2O3 (C-Al2O3) coatings were prepared by adding glycerol to the electrolytes, and coatings with reduced porosity and better high temperature oxidation resistance were obtained. SEM, EDS, XRD, XPS, high temperature oxidation test and first-principles calculation were used to study the structures and performances of the coatings. The results show that by adding glycerol to the electrolytes, the porosity of the obtained coatings is reduced. The doping of carbon (C) causes the XRD peaks of Al2O3 and XPS spectrum of Al2p and O1s.to shift to the left. The decrease in porosity is closely related to the increase in electrical conductivity of the coating caused by the doping of C, which reduces the band-gap of Al2O3. The coating with low C content shows the best high temperature oxidation resistance, while high C content coatings exhibit poorer high temperature oxidation resistance. Related mechanism is disclosed in the paper. •C-Al2O3 coatings were deposited onto TC4 by CPED using glycerol as carbon source.•The presence of C leaded to a decreased porosity of the coatings.•Coatings with low C content showed the best high temperature oxidation resistance.