| LI Jia-yi,KONG Ling-yan,LIU Jian-rong,XIONG Tian-ying.High Temperature Oxidation Resistance of Phosphate Coatings on Ti65 Alloy[J],49(3):171-179 |
| High Temperature Oxidation Resistance of Phosphate Coatings on Ti65 Alloy |
| Received:July 01, 2019 Revised:March 20, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2020.03.022 |
| KeyWord:Ti65 alloy high temperature oxidation resistance phosphate coating oxidation kinetics microstructure |
| Author | Institution |
| LI Jia-yi |
1.Institute of Metal Research, Chinese Academy of Sciences, Shenyang , China; 2.School of Materials Science and Engineering, University of Science and Technology of China, Shenyang , China |
| KONG Ling-yan |
1.Institute of Metal Research, Chinese Academy of Sciences, Shenyang , China |
| LIU Jian-rong |
1.Institute of Metal Research, Chinese Academy of Sciences, Shenyang , China |
| XIONG Tian-ying |
1.Institute of Metal Research, Chinese Academy of Sciences, Shenyang , China |
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| Abstract: |
| The work aims to improve the high temperature oxidation resistance of Ti65 with surface coating. Two types of high temperature oxidation resistance phosphate coatings were prepared on Ti65 alloy surface by spray with aluminum phosphate as the binder and Al particles and Al/SiC particles as the fillers. Oxidation behavior of Ti65 alloy and coated sample was investigated in quasi-isothermal static air of 650 ℃. XRD and SEM/EDS were used to characterize and analyze phase composition, microstructure and chemical composition of micro-area of the coated samples before and after oxidation test. EPMA was used to analyze the distribution of elements. From the results of high temperature oxidation test at 650 ℃, the quasi-isothermal oxidation kinetics curves of phosphate coating samples all conformed to parabolic laws and both coated samples had lower parabolic oxidation rate constant kp of 3.922×10-2, 1.768×10-2 mg/(cm2•h1/2) and 2.48×10-2, 3.385×10-4 mg/(cm2•h1/2)) than that of Ti65 alloy and the oxidation weight gain was significantly decreased. The aluminum phosphate coating with Al/SiC as fillers had the best oxidation resistance and the weight gain was 0.20 mg/cm2 after oxidation for 1000 h, which was about 1/6 of that of Ti65 base alloy (1.13 mg/cm2). From the microscopic analysis results, after quasi-isothermal oxidation at 650 ℃, an intermetallic (TiAl3) diffusion layer was formed between the coating and substrate alloy. Both coatings kept perfect without any crack and pore and effectively prevented the diffusion of oxygen into the Ti65 substrate, thus protecting the substrate from oxidation. Phosphate coating can effectively prevent oxygen diffusion to Ti65 alloy substrate at 650 ℃, and has excellent high temperature oxidation resistance. |
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