X-Ray Stress Measurement of Composite Plating(Ni-Co-P/a-Si3N4)(Part1. Residual Stress Measurement of Ni-Co-P Phase under the Consideration of the Stress Gradient)
Hideo Masuda, Shigeki Takago, Mitsuyoshi Hira and Yukio Hirose
Abstract:Ni-Co-P/a-Si3N4 composite plating excels in wear- and corrosion resistance. It is important to evaluate the residual stress due to the misfit of mechanical and physical properties between plating and substrate during the manufacturing and industrial using. However, in the case of plating specimen which have stress gradient, the sin2y method is not adequate to use because this material shows severely curved sin2y diagram. In this study, a fundamental investigation was carried out to apply the X-ray residual stress measurement of the plating material. Fourth kinds of specimens with different thickness of film were prepared. X-ray elastic constants were obtained using the non-liner analysis. Influence of the film thickness on curvature of 2q-sin2y diagram was simulated. Residual stress in the plating layer was analyzed under the assumption that the stress state is equivalent biaxial. Some experimental results were observed: sin2y diagrams were severely curved, and shape of diagrams shows varied by the film thickness and X-ray penetration depth. There is the steep stress gradient in the direction of depth. As the results, X-ray elastic constants of all specimens were independent from the thickness of film. Therefore, the value is constantly. A value of residual compressive stress calculated form present method is grater than value of sin2y technique. Compressive stress decreased with the film thickness. Key Words:Composite plating, Residual stress, X-ray elastic constants, Stress gradient, Experimental stress analysis, X-ray stress measurement