Abstract
Microstructures of the coatings and single deposited splats formed by advanced thermal spray processes have been investigated using two types of ion beam milling: one is broad argon ion beam for the cross-sectioning of thermal sprayed coatings in a cross section polisher and the other is focused gallium ion beam (FIB) for the cross-sectioning and transmission electron microscopy (TEM) sample preparation of single splats. The cross section of tungsten carbide cobalt (WC-Co) coatings fabricated by the polisher showed that it created a mirrored surface with minimized artifacts such as pull-outs of ceramic particles or smearing of pores which can be made by conventional metallographic preparations. A thin and locally re-thinned membrane of single nickel (Ni) splat was prepared by the FIB technique to observe the internal interface of particle/substrate in high resolution atomic scale images. It was found that the steel substrate was heavily deformed by the impact of a nickel particle with high kinetic and thermal energies. At the periphery region, the particle and the substrate were intimately bonded without any voids or gaps.
