Residual Stress Measurements of Cold Sprayed Tantalum Coatings

Coating residual stress level is a main parameter to control in order to prevent unacceptable deformation, spallation or cracking. If residual stress generation has been widely studied for plasma sprayed coatings only a few data are available for cold sprayed coatings. This study deals with the measurement and analysis of residual stress in tantalum cold sprayed coatings. Residual stress measurements are performed by two ways: hole-drilling and curvature methods. The first one gives a through thickness residual stress profile in the coating whereas the second one allows studying residual stress generation during spraying thanks to in-situ set-up. Results for both methods are consistent and show compressive stress of 340MPa for a coating built up on a 3mm thick copper substrate. This study reveals that with the used in-situ curvature method it is both possible to measure stress level during cold spray process but also to give information about the interface quality between coating and substrate.