Interface Bonding Properties of CrAlSiN-Coated Cemented Carbides Doped with CeO and YO Rare Earth Oxides.

This study performed first-principle-based calculations of the interface adhesion work in interface models of three terminal systems: CrAlSiN/WC-Co, CrAlSiN/WC-Co, and CrAlSiN/WC-Co. The results proved that the CrAlSiN/WC-Co and CrAlSiN/WC-Co interface models had the highest and lowest interface adhesion work values (4.312 and 2.536 J·m), respectively. Thus, the latter model had the weakest interface bonding property. On this basis, rare earth oxides CeO and YO were doped into the Al terminal model (CrAlSiN/WC-Co). Then, doping models of CeO and YO doped on the WC/WC, WC/Co, and CrAlSiN/WC-Co interfaces were established. The adhesion work value was calculated for the interfaces in each doping model. When CeO and YO were doped in the WC/WC and CrAlSiN/WC-Co interfaces, four doping models were constructed, each model contains interfaces withreduced adhesion work values, indicating deteriorated interface bonding properties. When the WC/Co interface was doped with CeO and YO, the interface adhesion work values of the two doping models are both increased, and YO doping improved the bonding properties of the Al terminal model (CrAlSiN/WC-Co) more significantly than CeO doping. Next, the charge density difference and the average Mulliken bond population were estimated. The WC/WC and CrAlSiN/WC-Co interfaces doped with CeO or YO, with decreased adhesion work, exhibited low electron cloud superposition and reduced values of charge transfer, average bond population, and interatomic interaction. When the WC/Co interface was doped with CeO or YO, superposition of the atomic charge densities of electron clouds was consistently observed at the CrAlSiN/WC-Co interface in the CrAlSiN/WC/CeO/Co and CrAlSiN/WC/YO/Co models; the atomic interactions were strong, and the interface bonding strength increased. When the WC/Co interface was doped with YO, the superposition of atomic charge densities and the atomic interactions were stronger than for CeO doping. In addition, the average Mulliken bond population and the atomic stability were also higher, and the doping effect was better.