Adhesion and residual stress evaluation of thermally sprayed coatings

For thermal sprayed coatings that are characterized by thick coatings, the adhesion to the substrate and residual stresses are the main parameters determining their performance in service. Although many methods have been tried to assess adhesion, there is no test, nowadays, that satisfies all requirements, both technical and theoretical, necessary to properly represent the adhesion of a coating on its substrate. The essential idea here is to compare several test methods capable of delivering an interface toughness or interfacial fracture energy representative of the adhesion of coatings. Various conditions of spraying as well as different materials and substrates were used. Apart from the EN582 standard test, indentation in-terfacial, in-plane shear and C-Rockwell indentation associated with a finite element modelling were used. The residual stresses were estimated using the curvature bending, the incremental hole drilling and the indirect method based on the results of the interfacial indentation. We show that the methods of interfacial indentation and in-plane tensile tests provide the best prospects in terms of consistency and reliability of the physical quantities obtained.

Autorentext

Mousab Hadad graduated in mechanical engineering in Switzerland in 2002, then works as scientist at "The Swiss Federal Laboratories for Materials Science and Technology" for 12 years in Tribology and topography lab, awarded his PhD from Lille University in 2010. since 2011 is leading a Characterization Laboratory in a private company