LOAD CARRYING CAPACITY OF Ni PLATED MEDIA IN SPHERICAL INDENTATION: EXPERIMENTAL AND THEORETICAL RESULTS

摘要

Spherical indentation experiments have been performed on aluminium and steel specimens. Some of the specimens were layered with electroplated nickel and all were surface coated with thin vapour deposited WC/C. The experimental results were compared with simulations made with the commercially available Elastica software package. The aim of the study was to investigate how an intermediate load carrying layer between a soft and compliant base material and a thin brittle coating can improve the resistance to plastic deformation. This study shows that thick and dense electroplated nickel layers, which give good adhesion both to base materials (aluminium and steel) and to PVD coatings (WC/C), can be produced and used as load carrying layers. As expected, it was found that an intermediate load carrying layer of sufficient thickness and suitable mechanical properties improves the load carrying capacity of soft and compliant base materials. It was also found that with a stiff layer on a more compliant base material, an intermediate layer that was too thin would decrease the load carrying capacity as compared with the homogeneous base material case. Finally, although not including plastic deformation, the analytical elastic calculations proved to be valuable for the interpretation of the experimental results.