Investigation of residual stresses in composite Ti+Al2O3 coatings deposited by thermal spraying onto ceramic substrate
Tomasz Chmielewski, Dariusz Golański, Grzegorz Gontarz
Quarterly No. 1, 2012 pages 26-32
DOI:
keywords: thermal spraying, residual stresses, composite coatings
abstract The residual stresses in thermally sprayed coatings are of great interest since they affect the reliability of the coating/substrate system. The evaluation of residual stresses in thermally sprayed composite Ti+Al2O3 coatings on Al2O3 ceramic substrates has been conducted. The purpose of the research was to measure the residual stresses generated in coatings deposited by detonation gun thermal spraying and compare the results obtained for pure titanium and Ti+30% Al2O3 composite coating. The stresses in deposited coatings have been obtained from the curvature measurement of the analyzed samples. A measuring system has been built for this purpose, which allowed registering of the curvature of the coated samples. The residual stresses have been calculated from the measurements using the Stoney equation and compared with the results obtained from the modified Stoney equation derived by Clyne. It was observed that tensile residual stresses are formed within the coating and grew with the coating increase. The applied stress calculation formula showed that for higher coating thicknesses, the primary Stoney equation underestimates the results comparing to the modified Stoney formula (Clyne).