CALCULATION OF RESIDUAL THERMAL-STRESS IN PLASMA-SPRAYED COATINGS

Residual internal stresses are induced in thermally-sprayed coating composite materials during deposition, owing to the different thermophysical properties of the substrate and coating materials and to the different spraying parameters. These residual stresses have a substantial effect on working properties, and therefore need to be taken into account in any optimization of the coating. Due to the wide variety of material and process parameters determining residual thermal stresses, systematic experimental testing is extremely effort, time and cost intensive. It is therefore necessary to determine residual stresses by means of mathematical techniques which, following experimental validation of the model, enable the influence of individual parameters on the residual thermal stress state of coating composite materials to be studied and the behaviour of the composite under practical conditions to be predicted. This paper presents a model of this kind. Calculated results for aluminium oxide and zirconium oxide on various substrates (process: plasma spraying) are compared with measured results, showing good agreement.