The use of the loading curve to assess soft coatings

A theoretical equation to determine the dependence of load P on the displacement h for plastic and elastic deformations under a Berkovich indenter is derived. This theoretical P-h relation was fitted to the experimental data for organic-inorganic hybrid coatings and glass and used to determine the elastic modulus and hardness. Either a plot of P/h(2) vs, hi (or h) or a plot of partial derivative P/partial derivative h(2) vs. h(2) (or h) can be used to assess fracture. Advantages and disadvantages of these approaches are discussed. (C) 2000 Elsevier Science S.A. All rights reserved.