High-temperature friction behavior of amorphous carbon coating in glass molding process

In the glass molding process, the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated temperature. To improve the chemical inertness and anti-friction properties of the mold, an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8 Co) substrate by magnetron sputtering. The friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the mold. Therefore, the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high temperature. Meanwhile, the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), Ramon spectroscopy, and atomic force microscope(AFM). The results showed that the amorphous carbon coating exhibited excellent thermal stability, but weak shear friction strength. The friction coefficient between the glass and coating depended on the temperature. Besides, the service life of the coating was governed by the friction force of the contact interface, processing conditions, and composition diffusion. This work provides a better understanding of the application of carbon coatings in the glass molding.