Preparation and Toughness Optimization of (Alcrsin/Tin)20/Ti Multilayer Multistage Bionic Tool Coatings

Abstract

To obtain the high hardness and excellent toughness of tool coating, here, the (AlCrSiN/TiN)20/Ti multilayer multistage bionic (MB) coatings were prepared on WC-6wt. % 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 Si3N4 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 improve 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, fracture toughness (KIC, 3.39±0.248 MPa×m1/2), and scratch crack propagation resistance (CPRs, 693.71 N2) in this study. The results may promote the application of the coated cutting tool in the high-speed cutting process.

Keywords: Multistage bionic coatings, multilayer, Fracture toughness, Resistance to crack damage, High-speed cutting