Preparation and toughness optimization of (AlCrSiN/TiN)20/Ti multilayer multiscale bionic tool coatings

To obtain the high hardness and excellent toughness of tool coating, here, the (AlCrSiN/TiN)20/Ti multilayer multiscale bionic (MB) coatings were prepared on WC-6 wt% Co substrates with a TiAlN buffer layer by changing the negative bias voltage of the Ti layer. The results show that the hardness and toughness are outstanding simultaneously. The excellent hardness is mainly from the nanocrystalline AlN, CrN, TiN, and amorphous Si-N(O) formed a nanocomposite structure in the nano multilayer of the AlCrSiN/TiN, which was confirmed by the results of TEM, XPS, and XRD. The excellent toughness is mainly from the multilayer structure and the Ti layer which improves the ability resistance to crack damage. Moreover, the toughness is adjusted by the negative bias voltage of the Ti layer. The MB4 coating sample with the negative bias voltage of −120 V shows the best H/E* (0.073), H3/E*2 (0.131 GPa) values, and scratch crack propagation resistance (CPRs, 653.54 N2) in this study. The results may promote the application of the coated cutting tool in the high-speed cutting process.