The influence of sandblasting on the morphology of electroless deposited zinclayers on aluminum sheets

The studies of sandblasting and the subsequent zincate treatment of Al99.5 sheets indicate that sandblasting is necessary to achieve a homogeneous coverage of the surface. Untreated and coated aluminum sheets of industrial origin exhibit poor coverage degrees of about 75%. To enhance the coating quality, two different grain sizes of SiC powder are applied in the sandblasting process. F 320 and F 80 blasting grits are used in the pretreatment procedure and the application of both results in higher degrees of coating up to 85% and 82%, respectively. Furthermore, blasting pressures in the range of 1-4 bar are used to create a rough but also uniform surface morphology. It is shown that a blasting pressure of 2 bar is an acceptable parameter to pretreat Al99.5 sheets. The investigations indicate that fine grain sizes such as F320 and an average blasting pressure of 2 bar form a successful parameter set for the pretreatment prior to the zincate process. In addition the evolution of zinc coatings on the basis of the zincate treatment is discussed within the parameter study.