A Novel Method for Specimen Preparation and Analysis of CVD Diamond Coated Tools Using Focussed Ion Beams (FIB) and Scanning Electron Microscopy (SEM)

Abstract

Investigations of the microscopic properties of chemical vapor deposited diamond coatings on tungsten carbide tools are important to understand the coating–substrate interface (Uhlmann et al. in Prod Eng Res Dev 11(2):83–86, 2004; Surf Coat Technol 131, 395–399, 2000), the coating morphology, and the properties of cracks. Commonly the microscopic properties are analyzed in the transmission electron microscope (TEM). This paper presents a novel investigation method that includes a faster specimen preparation and that offers new analyzing possibilities. It applies a well-established device combining a scanning focused ion beam (FIB) column for the preparation of the specimens and a scanning electron microscope (SEM) for the analysis of the specimen. The aim of the paper is to verify preparation parameters for which the microscopic properties of the diamond coating are preserved during the FIB preparation and to show that the SEM analysis provides the same results of microstructure and element distribution compared to the TEM analysis. Furthermore, the feasibility of new analysis methods is studied. The FIB/SEM method traces and images defects in the nanometer range like cracks, crack propagation directions, delaminations, and layer inhomogeneities directly. The bulk FIB-prepared specimens are suitable for a precise standard-based element quantification and distribution analysis using energy or wavelength (WDX) dispersive X-ray spectroscopy. Moreover, the WDX analysis distinguishes between graphite-like carbon and diamond.