| SUN Yi-hang,ZHANG Bao-cai,JIA Xiu-jie,LI Fang-yi,ZHANG Jian,WANG Guang-cun.Removal Effect of Molten Salt Cleaning for Paint Coatings on Remanufactured Parts[J],47(9):279-286 |
| Removal Effect of Molten Salt Cleaning for Paint Coatings on Remanufactured Parts |
| Received:June 03, 2018 Revised:September 20, 2018 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2018.09.037 |
| KeyWord:remanufacturing paint removal molten salt cleaning gasification thermal expansion oxidation activation energy |
| Author | Institution |
| SUN Yi-hang |
1.a. School of Mechanical Engineering, b. National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan , China |
| ZHANG Bao-cai |
1.a. School of Mechanical Engineering, b. National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan , China |
| JIA Xiu-jie |
1.a. School of Mechanical Engineering, b. National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan , China |
| LI Fang-yi |
1.a. School of Mechanical Engineering, b. National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan , China |
| ZHANG Jian |
1.a. School of Mechanical Engineering, b. National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan , China |
| WANG Guang-cun |
2.XCMG Research Institute, Xuzhou , China |
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| Abstract: |
| For the problems of remanufactured parts including low surface paint removal efficiency and incomplete cleaning, the work aims to use molten salt cleaning technology for cleaning, study removal mechanism of molten salt cleaning thoroughly, and compare the reasons of high removal efficiency of molten salt cleaning with those of thermal decomposition treatment. Micro-morphology of the paint was observed by SEM. Besides, internal structural characteristics and element distribution of the paint were analyzed. Based on former results, gasification, thermal expansion and oxidation effects of molten salt cleaning were further explained. Thermogravimetric experiment was used to determine temperature at which the maximum weight loss rate of paint and paint and molten salt mixture occurred, kinetic analysis of pyrolysis process was carried out in Coats-Redfern integration method, and corresponding activation energy of thermal decomposition and in the molten salt was calculated. A distinct layered structure consisting of an epoxy resin primer and a polyurethane-based finish appeared inside the paint. Main components of the structure were organic substances. The surface would be softened under high-temperature conditions. Therefore, thermal expansion effect of the molten salt did not significantly affect paint removal, and gasification and oxidation effects in the molten salt removal mechanism were the main removal effects. According to the thermogravimetric experiment result, it could be seen that the molten salt exhibited good thermal stability and large heat capacity at about 300 ℃. Compared with high temperature thermal decomposition, the molten salt made the maximum decomposition rate of the paint reduce from 350 ℃ to 305 ℃, and decomposition activation energy of the paint reduce from 114.4 kJ/mol to 74.1 kJ/mol. Main removal mechanisms of molten salt cleaning are gasification and oxidation, which can effectively reduce the maximum decomposition rate of paint and activation energy required by decomposition reaction, improve efficiency of paint removal, and reduce reaction temperature. |
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