Electrochemical Corrosion Evaluation of Thermal Spray Coatings Used as Environmental Barrier

Alumina and yttria coatings are used for semiconductor processing equipment for corrosion and arcing resistance. It is not only the corrosion of the coating material itself that is important, but also the interconnected porosity in the thermal spray coating that determines the long term performance of coated component. Electrochemical techniques provide a mean for accelerated corrosion evaluation and understanding into the corrosion mechanism taking place. A cyclic polarization technique was used to study the corrosion behavior of several different thermal spray coatings and substrate alloy combinations. This technique was also found to be useful in evaluating through thickness interconnected porosity in the coating.