Influence of CH Flow Rates on Optical Properties, Surface Roughness, and Residual Stress of Ti/WC Thin Films Deposited on Glass Substrates.

This paper investigates the influence of CH flow rates on the optical properties, surface roughness, and residual stress of Ti/WC thin films deposited on glass substrates. A range of Ti/WC thin films with varying carbon contents were prepared using the reactive pulsed DC magnetron sputtering technique. The properties of the Ti/WC films can be tuned by adjusting the deposition parameters, among which the acetylene (CH) flow rate plays a key role in determining the thin film's microstructure, optical properties, and stress behavior. The optical properties of the thin films were analyzed using UV-visible-NIR spectroscopy and Fourier transform infrared (FTIR) spectroscopy, the surface morphology was analyzed using microscopic interferometry, and the residual stress in the films was measured using a homemade Twyman-Green interferometer. The measurement results show that the average reflectance of Ti/WC films decreases with the increase in the CH flow rate, and the measured value changes from 52.24% to 44.56% in the wavelength of 400-800 nm. The infrared reflectance of Ti/WC films in the wavelength of 2.5-25 μm is 81.8% for 10 sccm, 80.8% for 20 sccm, 77.2% for 30 sccm, and 73.6% for 40 sccm. The tensile stress of the Ti/WC films deposited on B270 substrates increases with the increase in the CH flow rate, and the stress value changes from 0.361 GPa to 0.405 GPa. The surface roughness of Ti/WC films initially increases and then decreases slightly with the increase in the CH flow rate. These results indicate that the CH flow ratio significantly affects the reflectance in the visible and infrared bands, surface roughness, and residual stress of the Ti/WC films, which is of great significance for optimizing thin film performance to meet specific application requirements.