Research on Titanium Ion Etching Pretreatment Process on Cemented Carbide Before DLC Film Deposition

Before depositing a thin film, modifying the substrate surface was a crucial step in the film preparation process, having a decisive impact on the final properties of the film. In addition to additive methods such as preparing transition layers, subtractive methods such as etching treatment could also enhance the performance of the film. Using titanium ions to etch and pretreat the surface of cemented carbide was an effective optimization method for depositing DLC films. This paper investigated the influence of process parameters for titanium ion etching of cemented carbide on the substrate surface. By varying the substrate negative bias voltage, medium-frequency current, and argon gas flow rate, the etching rate, roughness, and elemental changes of the etched surface were studied. DLC films were then deposited on the etched surfaces to investigate the effect of the changes of surface characteristics on subsequent film deposition. The research revealed that the substrate negative bias voltage had the most significant impact on the etching rate, while the MF current affected the surface roughness. The increase in surface roughness can enhance the deposition rate. The changes in C/W ratio did not exhibit a clear impact pattern on the DLC film. However, an increase in Co element content improved the properties of the DLC film due to the diffusion of sub-surface Co element.