Influence of preliminary metal-ion etching on the topography and mechanical behavior of TiAlN coatings on cemented carbides

Metal-ion etching is widely used in substrate surface modification before coating by physical vapor deposition . In this work, TiAlN coatings were synthesized onto cemented carbides with Ti-, Cr-, and Zr-ion pre-etching by cathodic arc evaporation and investigated concerning surface topography and mechanical failure. The pre-etching of energetic metal ions introduces droplet defects and increases surface roughness through uneven bombardment. The high interface roughness and deposition of nanoscale metal interlayers contributed to the upgraded adhesion between the coating and the substrate. As a result, the adhesion strength of TiAlN coatings advances to more than 95 N by applying Cr- and Zr-ion pre-etching. The rough substrate surface also gives rise to a rough coating surface associated with the pre-etching time. Under normal loading, the microscopic pit-like surface morphology , stemming from ion etching, interrupts the transverse propagation of the circumferential cracks but does not affect the longitudinal crack propagation inside the coating. In addition, the higher roughness of coatings with ion pre-etching causes a shorter run-in stage during ball-on-disc tests due to the higher contact stress between the friction pair. • TiAlN coatings were deposited on cemented carbide with various ion pre-etching. • The ion etching changes the substrate surface, significantly increasing roughness. • Scratch adhesion strength above 95 N can be obtained by suitable ion pre-etching. • Rough surfaces lead to intermitted circumferential cracks under normal loading. • The ion pre-etching can also shorten the run-in period during friction tests.