ABSTRACT
This chapter gives an overview of some of the more promising contemporary research into nondestructive testing methods, which may have potential for the assessment of the “quality” and thickness of plasma-sprayed coatings. Through the incorporation of sophisticated electronic and microprocessor control technologies, plasma-spray processes are becoming more capable of integration into advanced, automated, and controlled manufacturing systems. The “quality” of a sprayed product is invariably a compromise. Ever-increasing demands for more severe service conditions, as well as the control of in-process conditions—technical, environmental, safety, and economic—can all influence quality. The purpose of any nondestructive test, therefore, must be to assess the integrity of a coating and hence confirm its ability to perform the function for which it is intended. The various nondestructive testing methods that are becoming available for coatings have the potential to measure different physical properties, and each, therefore, will give a different measure of integrity.
