Improving the adhesion of diamond-like carbon films on glass substrate by chemical etching and oxygen plasma treatment

The weak adhesion of diamond-like carbon (DLC) films on glass has hindered their widespread application. Despite extensive research on interlayers to enhance adhesion, the challenge of poor DLC adhesion on glass surfaces remains unresolved. In this study, a new strategy is proposed to improve DLC adhesion on glass. Initially, the glass was chemically etched to generate continuous and micrometer-sized pits on the surface. Subsequently, oxygen plasma treatment was employed on the etched glass to increase the Si–OH content on the surface. SiO2, SiOC and DLC were then sequentially deposited on the etched glass using magnetron sputtering. The film materials were embedded into the pits, resulting in a wavy 3D morphology. This morphology facilitated the distribution of applied force on the inclined planes of the pits and increased the contact area between the film and the glass surface, thereby improving the chemical bonding between the film and the substrate. The adhesion strength, Vickers hardness and pencil hardness of the films on the glass were 135.37 mN, 751.8 HV and 8H, respectively. These results demonstrate the effectiveness of the proposed approach in addressing the issue of weak DLC adhesion on glass. The findings of this study have potential applications in various fields. •Closely arranged spherical pits were chemically etched on the glass surface.•O2 plasma treatment increased the number of active groups on the glass surface.•SiO2, SiOC and DLC films were sequentially sputtered on the etched glass.•The adhesion and Vickers hardness of DLC film on the glass was significantly enhanced.