On the high temperature oxidation behavior of AlCrBN/TiAlNbSiN multilayer coatings with addition of boron and silicon

Developing a TiAlN-based hard coating with a multilayer structure comprising multiple nitride components shows potential to enhance the overall performance of high temperature applications. In this study, multi-target cathodic arc evaporation was utilized to deposit multilayer coatings comprising of nanostructured AlCrN/ TiAlNbN and AlCrBN/TiAlNbSiN. The focus of this study is to analyze how the different coatings undergo structural changes due to the growth of oxide scale and diffusion processes that take place during oxidation when subjected to high temperatures of 900 C-degrees, and the roles of B and Si addition in their oxidation resistance were examined. The deposited AlCrN/TiAlNbN coating showed a typical columnar structure with nanolayer stacking (average bilayer periodic thickness - 14.8 nm). The surface formed an oxide layer rich in titanium oxide, while the internal oxide layer of the AlCrN/TiAlNbN coating that underwent oxidation contained mixed metal oxides with a dominant composition of Al2O3, which hindered additional oxidation. The AlCrBN/TiAlNbSiN coatings, which had average bilayer periodic thickness 11.4 nm -12.2 nm, showed fine-fibrous growth morphologies and refining effects of B and Si in the AlCrBN/TiAlNbSiN coatings, and they possessed better high temperature oxidation resistance thang that of AlCrN/TiAlNbN. Due to the formation of a protective oxidized layer with a combination of metal oxides, which minimizes the inward diffusion of oxygen during oxidation, the AlCrBN/ TiAlNbSiN coating with a thicker AlCrBN layer exhibited the highest resistance to oxidation compared to the other coatings studied.