On the Application of Acoustic Emission Analysis to Evaluate the Integrity of Protective Coatings on High-Temperature Alloys

Abstract

Protective coatings extend the range of applications for materials. Surface properties can be selectively adapted for each problem. Thus bare high-temperature alloys for heat exchanging units used e.g. in high-temperature systems for producing substitute natural gas do not have sufficient protection against undesirable tritium permeation from the helium primary gas into the substitute natural gas generated. A chromium oxide coating, on the other hand, of only a few µm in thickness ensures a barrier effect combined with an inhibitive factor H = 1000¹.