EVALUATION OF THE ADHERENCE OF PROTAL COATINGS BY ROCKWELL INDENTATION

In order to optimize the PROTAL^® process (laser assisted thermal spraying), the toughness of the substrate/coating interface has been determined quantitatively by Rockwell C indentations. The indentation imposes surface strains of the substrate which increase the strain energy in the coating leading to coating delamination around the indentation. The interface fracture toughness can be determined quantitatively from a finite element calculation of the indentation. Using this method, the interface toughness of A1₂0₃-13%TiO₂ coatings on TiA16V4 and on Al 6082 substrates have been compared in this work for different laser treatment parameters. In particular, the influence of the laser beam intensity and of the time interval between the laser treatment and the spraying have been studied. The results are compared with the toughness of degreased and grit-blasted substrates.