Studying the Effect of Silicon and Oxygen on the Structure and Performance of Titanium Nitride Coatings

Titanium nitride (TiN) coatings have a wide range of applications due to their practical properties such as high hardness, good corrosion resistance, heat resistance and excellent wear resistance. They have been widely used in various industries including decorative coatings, diffusion barriers and hard coatings. The properties of TiN can be greatly enhanced by addition other elements, such as Si [1-3]. Incorporation of Si in the TiN cubic structure leads to formation of TiSiN coatings characterized by high hardness and high oxidation resistance up to 800 °C. This enables synthesizing coatings and designing materials with a broad range of applications, especially as materials that should perform under harsh environments. The ternary TiSiN system is formed due to the total miscibility of Si, which creates a solid solution while preserving the crystalline structure B1 of TiN. Si is also believed to create nanocomposite structure of TiSiN coatings consisting of nanocrystalline TiN grains encapsulated by an amorphous silicon nitride (Si₃N₄) matrix. To achieve high hardness TiN films, significant bonding strength between Ti and N must be achieved. If the bonding is too weak, the surface of the coating can oxidize, forming titanium oxynitride and eventually TiO₂ even at room temperature conditions [4]. The oxynitride and oxide forms are known to exhibit a lower hardness than TiN and experience oxidation propagation.<br/><br/>This study is focused on the effect of Si and oxygen level on the TiN film’s characteristics. X-ray Photoelectron Spectroscopy (XPS) was used to study the compositions and high resolution XPS was used to determine the surface oxide to nitride ratios. Mechanical tests were performed with nano indenter to determine the hardness of these coatings. The study shows the correlation between the hardness of the films and the percentage of the XPS titanium oxide component. X-ray diffraction confirmed the formation of titanium nitride cubic phase and different crystallographic orientations were observed depending on the composition of each film. The results of this study show that adding Si and reducing the oxygen level improved the performance of the TiN films as hard coatings.<br/>1. Akhte, Rumana; Zhou, Zhifeg; Xie, Zonghan, Munroe, Paul <i>Surface and coating technology</i> 425 (2021) 127687.<br/>2. Akhte, Rumana; Zhou, Zhifeg; Xie, Zonghan, Munroe, Paul <i>Applied surface Science</i> 563 (2021) 150356.<br/>3. Greczynski, G.; Bakhit, B.; Hultman, L.; Odén, M.<i> Surface and coating technology</i> 398 (2020) 126087.<br/>4. Logothetidis, S.; Meletis, E.I.; Stergioudis, G.; Adjaottor, A.A. <i>Thin Solid films</i> 338 (1999) 304.<br/><br/>This material is based upon work supported by the U.S. Department of Energy, Office of Fossil Energy and Carbon Management under Award Number FE0031911.