Hardcoat

Hardcoat, or hard coating, is a protective surface treatment intended to increase hardness, wear resistance, and durability of a substrate. It is commonly applied to polymers, especially polycarbonate, and to metals through conversion coatings. The main approaches are hard anodizing (Type III) on aluminum, which forms a thick, dense oxide layer, and surface-applied polymer hardcoats—UV- or heat-c cured films that bond to the substrate to improve scratch and abrasion resistance. Some modern hardcoats incorporate ceramic particles or use sol–gel and vapor-deposition processes to achieve higher hardness and chemical resistance.

Applications of hardcoats span aerospace, automotive, electronics, optics, and protective gear. Hard anodizing yields a very hard, corrosion-resistant metal surface and can be dyed for aesthetic or identification purposes, while plastic hardcoats provide scratch resistance for items such as eyeglass lenses, smartphone screens, and protective housings. Limitations include potential brittleness or delamination under heavy impact, thickness buildup that can affect tolerances, and sensitivity to UV light or chemicals depending on coating chemistry. For plastics, UV stabilization is important to prevent yellowing and degradation; for metals, compatibility with underlying alloys and mechanical design is important to avoid cracking under stress. Standards and testing typically cover pencil hardness, abrasion resistance, adhesion, and environmental aging. Regular cleaning with mild, non-abrasive cleaners helps preserve coating integrity.