Study on Surface Roughness Modification of Graphite Mold through Infiltration Process

Graphite molds are widely employed in high-temperature glass molding processes because of their excellent thermal stability, machinability, and cost-effectiveness. However, the intrinsic porosity of graphite results in poor surface roughness, which restricts its application in large-area freeform optical components such as automotive head-up display (HUD) mirrors. This study developed a surface modification process based on impregnation and carbonization employing a furan resin to improve the surface quality of graphite molds. An optimal furan- to-ethanol weight ratio of 7:3 enabled effective pore filling and densification of the graphite surface. After carbonization and polishing, the modified graphite mold exhibited a significantly reduced surface roughness of approximately 60 nm (Ra). The proposed impregnation-carbonization approach was successfully applied to a large-area graphite mold for HUD glass mirror.