Bonding strength of fluoridated hydroxyapatite coatings: A comparative study on pull-out and scratch analysis

Abstract In this study, fluoridated hydroxyapatite coatings are prepared on Ti6Al4V alloy substrate through sol–gel method. The bonding strength is evaluated through two different methods: pull-out method and scanning scratch method. Both results show F incorporation could effectively increase the bonding between coating and substrate. It is found that the pull-out results are actually compounds of adhesion failure, cohesive failure and glue failure; while the critical loads in scanning scratch show only the coating-matrix adhesion strength. It is suggested that scanning scratch test is more suitable to evaluate the bonding strength of bioactive ceramic coatings.