Crater Wear Evolution in Multilayer Coated Carbides During Machining Using Confocal Microscopy

Steady-state turning experiments were carried out with multilayer coated inserts consisting of TiN/Al2O3/TiCN deposited on a carbide substrate. Confocal microscopy was used for the first time to observe the topography of crater wear evolution in multilayer coated inserts. A hump made of TiN coating next to a growing crater of Al2O3, traces of attached steel, and the maximum depth regions have been identified. Scoring marks were also detected in the TiN layer, indicating the presence of abrasion wear. Interestingly, the crater depth was stagnant once it reached the Al2O3 layer, and the wear progresses by broadening the area of exposed Al2O3. It was concluded that the effectiveness of multilayer coated tools comes from the dissolution resistance of the Al2O3 layer, which delays depth growth and develops the wear front into a wider area. Confocal microsocopy was found to be a valuable tool to obtain wear topography for multilayer coated tools.