STRENGTH AND TOUGHNESS MEASUREMENT OF THIN BRITTLE COATINGS ON SUBSTRATES .1. THEORY AND MEASUREMENT

Conventional mechanical property measurement techniques usually cannot be applied to ceramic thin films because of the small amount of mater ial involved. A method is described to determine the ultimate tensile strength, fracture toughness, Weibull modulus, and surface energy of m icron-sized ceramic films on substrates. This technique is based on me asuring the radius of curvature of a coated substrate at room temperat ure, and equating the resulting calculated stress with a theoretical s hear-lag stress distribution model using a force balance.