Starch media blast cleaning, properties and performance of masking tapes and aged paint films

grantor: University of TorontoStarch Media blast cleaning is an environmentally benign method for coating removal from aircraft. The main objective of this work was to provide a method for predicting the paint stripping rate of an aged paint system, through a knowledge of some fundamental physical properties of the paint substrate system, i.e., hardness and modulus of elasticity. It was shown that aging of aluminum panels painted with polyurethane significantly increased the hardness of the coatings, while the process did not have a significant effect on the coating modulus of elasticity. It was also shown that the coating became more erosion resistant as it aged. Finally, it was shown that it is possible to predict the paint removal rate by in situ measurement of coating dynamic hardness (coefficient of restitution) using Leeb's principle. The effectiveness of masking tapes in resisting erosion and edge lifting during media blasting was investigated. It was concluded that the erosion resistance of masking tapes depends on the coefficient of restitution; the higher the coefficient of restitution the less the plastic deformation of the tape and the greater the incident kinetic energy restored in the springback. Finally, a model was developed to explain the erosion resistance of the masking tapes and aged coatings based on two material properties, the modulus of elasticity and the dynamic hardness. It was concluded that the higher the coefficient of restitution, the more erosion resistant is the coating.M.A.Sc