Measuring coating internal stresses by the curvature method applied to a beveled sample

Internal stress of high tungsten content Ni-W alloy coatings

“…The internal stress in the electrodeposition caused the strip to bend. The mechanical stress was calculated using the Stoney equation below [37]:…”

“…The internal stress in the electrodeposition caused the strip to bend. The mechanical stress was calculated using the Stoney equation below [37]: f and s represent the coating and the substrate, respectively; t and r represent thickness and radius of curvature, respectively: E ( E s = 97.2785 GPa) and v ( v s = 0.31) represent the elastic modulus and Poisson's ratio of the substrate, respectively.…”

Fast evaluation of the temperature dependence of residual stress in ceramic coatings via an image relative method

“…Therefore, residual stress in the coating can be accurately estimated from the change in the bending curvature radius of the beam sample using the traditional Stoney's formula. 7 This formula has been derived as an international standard 8 and is widely used in the residual stress analyses of thin films and coatings, [9][10][11][12] favoring a convenient estimation of residual stress in beam specimens with one-side coatings and significant bending deformations. However, the practical application of the Stoney's formula is limited in many cases, 7,[10][11][12][13] including residual stress calculations at high temperatures, because bending deformations are difficult to measure accurately at such high temperatures, and residual stress is not detected in symmetrically coated samples because of the minimal change in the bending deformation.…”

“…7 This formula has been derived as an international standard 8 and is widely used in the residual stress analyses of thin films and coatings, [9][10][11][12] favoring a convenient estimation of residual stress in beam specimens with one-side coatings and significant bending deformations. However, the practical application of the Stoney's formula is limited in many cases, 7,[10][11][12][13] including residual stress calculations at high temperatures, because bending deformations are difficult to measure accurately at such high temperatures, and residual stress is not detected in symmetrically coated samples because of the minimal change in the bending deformation. It should be emphasized that residual stress is not a material constant and that the value measured for a bent sample does not represent the residual stress generated in the coating of a symmetrical component.…”