Response of Thermal Barrier Coatings to Waterjet with Soluble Abrasives: Machining Performance and Material Removal Mechanisms

• The waterjet with soluble abrasives addressed the problem of low efficiency for coating removal in thermal barrier coatings without abrasive embedment. • The material removal mechanisms of plain waterjet and waterjet with soluble abrasives in complex brittle materials were revealed and studied. • The introduction of local machining forces resulted no significant stress concentration in both waterjet methods. • A mathematical model was established to predict the results of waterjet coating removal and validate its material removal mechanisms. Waterjet coating removal is an advanced non-conventional machining technology, that typically utilizes high-pressure water mixed with abrasives to achieve precise and effective surface cleaning. However, abrasive embedment can become a severe problem, particularly affecting the functional performance of coatings in the aerospace sector. A novel method uses water-soluble abrasives to address this issue, which results in less surface contamination compared to conventional abrasives. Through a series of tests, soluble abrasives (i.e., sugar) were demonstrated to increase the material removal rate by over 58% compared to plain waterjet (PWJ) using the same parameters. To improve coating removal capability for industrial applications, this work also investigated the material removal mechanisms of plain water impact in PWJ and erosion of accelerated abrasives in abrasive waterjet (AWJ), evaluating the surface quality after applying the two coating removal methods. In PWJ, material blocks were removed by long cracks depending on the lamellar structure, whereas in AWJ, the coating was eroded into debris and subsequently carried away by the water stream. To validate the machining performance and material removal mechanisms of waterjet with soluble abrasives, different jet energy distributions were used to establish and calibrate a mathematical model capable of predicting the results of waterjet coating removal. This novel waterjet coating removal method has significant potential in industrial applications.