Coating removal from aluminum using wheat starch blast cleaning

grantor: University of TorontoWheat starch blast cleaning is increasingly used to remove organic coatings from aircraft. The aim of this work was to maximize the productivity of the process by gaining a better understanding of the mechanism of coating removal, and by studying how various process parameters affect it. The impact sites left by individual wheat starch particles on the coating were examined, the size and shape of the particles were studied, and particle velocities were measured. The relationship between particle size and velocity was also explored using a mathematical model. Finally, the results of these experiments were correlated with paint removal rates, which were found to depend strongly on nozzle angle and particle velocity, but also depended on particle size and shape. The best paint removal rates were achieved at a nozzle angle of 45$\sp\circ,$ and it was shown that the topcoat was removed in a cumulative fashion by chipping (ductile erosion). Lastly, a selective stripping "window" was observed for the coating system studied, i.e. it was possible to remove the topcoat while leaving the underlying primer intact.M.A.Sc