Adhesive strength and structure of micro-arc oxidation ceramic coatings grown in-situ on LY12 aluminum alloy
(1.Department of Applied Chemistry, Harbin Institute of Technology Harbin 150001, China
2.黑龙江省哈尔滨市哈尔滨工业大学应用化学系)
2.黑龙江省哈尔滨市哈尔滨工业大学应用化学系)
Abstract: The ceramic coatings containing zirconium dioxide were grown in-situ on LY12 aluminium alloy by micro-arc oxidation in mixed zirconate and phosphate solution. The phase composition and morphology of the coatings were studied by XRD and SEM. The adhesive strength of ceramic coatings was assessed by thermal shock test and tensile test. The results show that the coating is composed of m-ZrO2, t-ZrO2, and a little γ-Al2O3. Along the section of the coating, t-ZrO2 is more on both sides than that in the middle, while m-ZrO2 is more in the middle than that on both sides. Meantime the coating is also composed of a dense layer and a loose layer. The coating has excellent thermal shock resistance under 550 ℃ and 600 ℃. And tensile tests show the adhesive strength of the dense layer of the coating with the substrate is more than 17.5 MPa.
Key words: LY12 aluminum alloy; micro-arc oxidation; ZrO2 ceramic coating; adhesive strength