RELAXATION OF RESIDUAL STRESSES IN BRUSH-PLATED GOLD COATING

摘要

In this study residual stresses were determined in a gold coating deposited from a commercial SIFCO Dalic Solution (Gold (Hard Alloy), Code SPS 5370) on copper and brass substrates with different thicknesses. The calculation formula is extended Stoney's formula which takes into consideration the real shape of the substrate, and the difference between the elasticity moduli and the coefficient of thermal expansion of the coating and the substrate materials. Residual stresses in coatings represent significant tensile stresses and their maximum values are higher than the values of stresses in coatings obtained in a bath solution. The values of residual stresses decrease markedly and after nine months they are many times smaller than after deposition. The sensitivity of the method was studied and the expanded uncertainties of the computed mean values of the residual stresses are presented. Substrate deformation depending on coating thickness is examined.