Ultra-Hard Anti-Friction Anti-Reflective Film for Display System
Objective With the rapid development of display technology,digital display screens are increasingly integrated into daily life. To improve display clarity and reduce residual reflections,it is necessary to develop anti-reflective coatings for display windows. Although significant research has been conducted globally on high-performance anti-reflective coatings,conventional coatings often lack the required hardness and abrasion resistance to meet spectral performance standards. To address these issues,a new SiTiON low-refractive ultra-hard nanocomposite film has been developed. By incorporating the high-refractive index silicon nitride material,an ultra-hard anti-friction anti-reflective film for the visible light spectrum is prepared,effectively extending the service life of digital display windows.Methods Based on the Clausius‒Mossotti theory,a new SiTiON low-refractive ultra-hard nanocomposite film has been developed using medium-frequency magnetron sputtering. The preparation process is optimized by controlling variables and selecting optimal deposition parameters. Silicon nitride is chosen as the high and low refractive index material to design a visible-band ultra-hard anti-friction anti-reflective film on an aluminum-silicon tempered glass substrate. By adding a 10 nm AS liquid layer on the outermost layer of the anti-reflective coating,the abrasion resistance is significantly improved. Testing demonstrates that the film's hardness remains stable and does not affect spectral performance.Results and Discussions The effect of the nitrogen-oxygen mixing ratio on the low refraction of SiTiON is analyzed based on the Clausius‒Mossotti theory. When the nitrogen flow rate is constant,the refractive index of SiON decreases with increasing oxygen flow rate (Table 1),while TiON's refractive index increases (Table 2). Conversely,with constant oxygen flux,the refractive index of SiON increases with nitrogen flow rate (Table 3),while TiON's refractive index decreases (Table 4). The refractive index range of SiTiON is calculated from Eq. (1). The study also investigates the influence of different ICP power conditions on SiTiON film hardness and stress. Without ICP,SiTiON's hardness is 1416.2 HV and stress is-785.6 Mpa. As ICP power increases from 1 kW to 4 kW,hardness increases from 1431.8 HV to 1507.4 HV,and stress changes from-806.3 Mpa to-863.5 Mpa and then to-802.4 Mpa. At 5 kW,the film cracks as shown in Fig. 5,so ICP power is set to 4 kW for film preparation. The spectral curve of the prepared anti-reflective coating (Fig. 8) deviates significantly from the theoretical design due to minimal material absorption and surface/interface scattering. Abrasion resistance test shows that the hydrophobic angle of the film surface changes significantly before and after the friction test. Further experiments reveal that applying AS liquid improves abrasion resistance. After AS liquid evaporation,the hydrophobic angle changes by 1.55°,indicating enhanced abrasion resistance.Conclusions An ultra-hard,anti-friction,anti-reflective film for the visible light band has been developed according to the requirements of digital display windows. Based on Clausius‒Mossotti theory,the deposition process is optimized to produce a new SiTiON low-refractive ultra-hard nanocomposite film with a refractive index of about 1.483,low absorption,and hardness exceeding 1500 HV. Applying AS liquid to the film surface improves friction resistance. The average reflectivity of the ultra-hard,anti-friction,anti-reflective film in the 400‒700 nm wavelength range is 0.419％,with a hardness of 1796.4 HV. The hydrophobic angle of the film surface changed by 1.55° before and after the friction test. The film meets the practical requirements for display windows through various tests,including adhesion,temperature extremes,and constant temperature and humidity tests.
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