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 material involved. A method is described to determine the ultimate tensile strength, fracture toughness, Weibull modulus, and surface energy of micron-sized ceramic films on substrates. This technique is based on measuring the radius of curvature of a coated substrate at room temperature, and equating the resulting calculated stress with a theoretical shear-lag stress distribution model using a force balance.