Characterization of Al2O3 coatings oxidized from Al with different proportion of seed crystals at a lower temperature

• Published in: Applied surface science Vol. 283; pp. 87 - 93
• Main Authors: Wang, Chen, Lin, Yuebin, He, Fei, Luo, Xinyi, Tao, Jie
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.10.2013; Elsevier
• Subjects: Aluminum; Aluminum oxide; Austenitic stainless steels; Bonding force; Coatings; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Corrosion resistance; Cross-disciplinary physics: materials science; rheology; Crystals; Double cathodes discharge; Exact sciences and technology; Heat resistant steels; Oxidation; Physics; Protective coatings; Scanning electron microscopy; Seed crystals; Seeds; α-Al2O3 coatings; Corrosion resistance; α-Al2O3 coatings; Double cathodes discharge; Seed crystals; Bonding force; Aluminium oxide; coatings; Inorganic compounds; Crystal seeds; α-Al; Cathodes; O
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2013.06.030

•α-Al2O3 seed crystals were added into targets and sputtered to induce the growth of α-Al2O3 coatings.•At 580°C, the formation of α-Al2O3 was promoted by as-prepared seed crystals and energy bombardment during plasma oxidation.•The Al2O3 coating was compact, performing a good corrosion resistance and metallurgical bonding with the substrate.•The inducing effect of seed crystals became weak with the increment content of seed crystals. Al layer with α-Al2O3 seed crystals was prepared on the surface of 316L stainless steel (SS) by a double cathodes discharge technique, in which the mixed targets of pure Al doped with different proportions of α-Al2O3 were used. Then, Al2O3 coatings were obtained after plasma oxidization at 580°C. The phase composition, microstructure and morphology of the coatings were studied respectively by means of glancing-angle (1°) X-ray diffractometry (GAXRD) and scanning electron microscopy (SEM). Furthermore, the bonding force and corrosion resistance of the coatings were measured. The results indicated that α-Al2O3 nucleated and grew surrounding the seed crystals as the Volmer–Weber Mode. The Al2O3 coating was compact, performing a good corrosion resistance and metallurgical bonding. The inducing effects of α-Al2O3 with different fractions were discussed. α-Al2O3 (5.5wt.%) was distributed in the Al layer when the target possessing 10% α-Al2O3 was used. After plasma oxidation, 65.54wt.% α-Al2O3 was obtained which was 10.34% more than that obtained by the oxidation of pure Al at the same condition. However, the inducing effects became weak with the further increment of content of α-Al2O3 seed crystals.