탄소성 입입이론을 이용한 DLC 박막소재의 경도값 모델링 및 예측

We estimate the true hardness value of a thin film from composite hardness obtained by a conventional microhardness tester. To separate the substrate and film contributions to the composite hardness, we apply the plastic-zone volume-law-of mixtures theory through the stress analysis of indentation. At this time, the geometrical deformation types are considered: spherical for substrate and cylindrical for film to consider the surface effect. When an interface has a strong bonding, namely, no interface delamination occurs during loading, the deformation in the soft substrate is assumed to be restricted by the brittle film on condition that the strains of both film actually match at interface. And, in calculating the plastic-zone radii, the virtual pressures which the substrate and film actually support are considered. On the other hand, when an interface is wear, an interface parameter is introduced to reflect the partial debonding at interface during loading, resulting in the partial release of plastic-zone confinement in the soft substrate.