An analytical model for predicting residual stresses in progressively deposited coatings .1. Planar geometry

An analytical model has been developed to predict the residual stress distributions in progressively deposited coatings, such as those produced by thermal spraying. This is based on the concept of a misfit strain, caused by either the deposition stress (e.g. due to quenching of splats in thermal spraying) or by differential thermal contraction between substrate and coating during cooling. The deposition stress is introduced as the coating is formed layer-by-layer, with a specified layer thickness, such that the misfit strain is accommodated after each layer addition (rather than for the coating as a whole). From a knowledge of deposition temperatures, material properties and specimen dimensions, residual stress distributions can be predicted. The model is straightforward. It can be implemented with a simple customised computer program or by using a standard spreadsheet. Comparisons are presented between predictions from this model and from a numerical model for three plasma sprayed systems. Good agreement is observed and the predictions also serve to highlight various features of typical sprayed systems. (C) 1997 Elsevier Science S.A.