Research on the Effect of Molten Salt Ultrasonic Composite Cleaning for Paint Removal

Aiming at paint removal on hydraulic cylinder, the effect of molten salt ultrasonic composite cleaning was studied. First, the mechanism of molten salt cleaning and ultrasonic cleaning was reviewed. To further describe the composite cleaning mechanism, the components and internal structure of paint were analyzed by scanning electron microscopy and Fourier transform infrared. Results showed that the paint had a significant layered structure. The total thickness was about 100 μm, and the main components were organic matters, including ester groups, epoxy groups, and aromatic compounds. Then, combining with thermal environment, cleaning medium's property, and ultrasound, the composite cleaning mechanism was described in terms of three aspects: thermal effect, chemical reaction, and ultrasonic effect. Besides, the reason why this composite cleaning had good effect on paint removal, compared to paint heated in air, was explained through dynamic analysis, which was the reduction of reaction activation energy from 114.4 kJ/mol of paint alone to 74.1 kJ/mol.