Subsurface cracking during indentation on hybrid coatings on polycarbonate

Abstract

Subsurface cracking after nano- and Vickers indentation on transparent silica–(meth)acrylate hybrid coatings deposited on a polycarbonate substrate was observed for the first time. It appeared that after initiation at the interface, these cracks propagated toward the surface and in radial directions as the indentation load increased. It was found that, for chemically identical coatings, the thicker the coating, the higher load necessary to initiate these cracks. Subsurface cracks formed during nanoindentation occur at lower loads than the normally observed surface cracks and are accompanied by a very small change in the slope of the loading curve.