Research of high-hardness and wear-resistant SiO2 film coating on acrylic substrates

Acrylic (PMMA) possesses excellent optical transparency, good chemical stability as well as many other merits such as the feasibilities in dyeing and manufacturing. But its poor hardness and wear resistance restrict its industrialized applications. In order to improve the hardness and wear resistance, SiO₂ films were coated on PMMA substrates by both dip coating method and aerosol spraying method in this work. Heating curing method was carried out after the coating of SiO₂ film, and consequently, the mechanical properties, optical properties and surface morphology were characterized and compared. The experimental results showed that the SiO₂ films prepared by aerosol spraying method has a better performance in both hardness and wear resistance, compared with the films prepared by dip coating method. In the optimized conditions, the hardness of the PMMA was improved from 3H to ~8H, and the non-abrasion rubbing times increased from less than 100 times to 5000 times with a loading of 500g weight after the coating of SiO₂ film, indicating the improvement of the wear resistance.