Structural, Mechanical, and Decorative Properties of Sputtered TiN and Ti (N, C) Films for Orthodontic Applications; an In Vitro Study

Abstract

In this paper, we explore and modify the structural, mechanical, and decorative properties of films composed by TiN and Ti (N, C) with a wide range of N2 gas flow during the deposition in order to be used on orthodontic systems. The films were grown using reactive DC magnetron sputtering from a pure Ti target and customized with C pellets onto Si and stainless steel 316L substrates. The structural properties were studied using X-ray diffraction and scanning electron microscopy, while the mechanical ones were obtained through hardness, elastic modulus, and friction coefficient. Moreover, the wear rate has been measured under an artificial saliva medium to simulate the oral cavity. The color of the films deposited onto stainless steel 316 L substrate was characterized through CIELab color code. Our findings show that the addition of N2 and C in the Ti matrix improves the mechanical properties of the films. With the increase in the amount of N2 and C, the hardness reaches a value of 739 HV, higher than the one reported in the literature (600 HV), a low value of the coefficient of elasticity (8.0 GPa), and also a low friction coefficient (0.30). Moreover, with the addition of N2 and C in the Ti films, the color of the films changes from metallic aspect until “with” gold, which means that our coatings exhibit versatile mechanical and color characteristics to be used in orthodontic wires applications.

Functional Surface Coatings on Orthodontic Appliances: Reviews of Friction Reduction, Antibacterial Properties, and Corrosion Resistance

“…Among metal and metallic compound friction reduction coatings, tungsten disulfide (WS 2 ) was the first to be applied [ 22 ]. Since then, silver (Ag) coatings and metallic compound coatings, such as zinc oxide (ZnO) [ 23 , 24 , 25 , 26 , 27 ], titanium nitride (TiN) [ 28 , 29 , 30 , 31 , 32 , 33 ], and aluminum oxide (Al 2 O 3 ) [ 30 ], have also received good attention. Nonmetals, including carbon-based materials [ 34 ], polymers [ 35 , 36 , 37 , 38 , 39 ], and bioactive materials [ 40 ], are relatively new coating materials.…”

“…The current trend tends to combine TiN with other application materials. TiN-derived coating materials such as titanium carbonitride (TiCN) [ 31 , 32 ], multilayer titanium nitride/titanium (TiN/Ti) [ 33 ], and nickel-titanium-molybdenum (Ni-Ti-Mo) composite coatings [ 57 ] not only have a more exact friction reduction effect than TiN, but are also more beneficial to clinical application due to other advantages.…”

“…Therefore, overall, the TiCN film had better surface properties than TiN in the tested samples. More interestingly, the researchers also found that the colors of TiN and TiCN films have decorative aesthetic properties, so these two coatings may be among the future directions for the development of aesthetic friction reduction archwires [ 31 ]. Similarly, Jie Zhang et al found that TiN and TiCN coatings on SS surfaces can reduce surface friction, especially in artificial saliva [ 32 ].…”

“…However, for coatings on SS substrates, some new materials also have higher corrosion resistance than TiN. These coatings include titanium-diamond-like carbon (Ti-DLC) [ 166 ] and TiCN [ 31 ], and the corrosion resistance of TiCN increases with the nitrogen content and carbon content used in the preparation process [ 31 ]. In addition to SS, the use of TiCN coatings also reduced the amount of ions released from nickel-chromium-molybdenum (Ni-Cr-Mo) alloy substrates [ 167 ] and the mass loss of nickel-chromium (Ni-Cr) alloy substrates [ 168 ], indicating that the coatings improved the corrosion resistance of various metallic materials.…”

“…Some other metal and metallic compound coatings have corrosion resistance, but are mainly used for friction reduction, such as WS 2 [ 43 ], ZnO [ 24 , 25 , 26 ], and TiN [ 29 , 31 , 32 ]. The potential of the remaining metallic materials as corrosion-resistant coatings is still not enough for clinical applications, so there is still space for corrosion-resistant coatings to be developed using metallic materials.…”