Abstract
When machining difficult‐to‐cut, nonferrous materials, chemical vapor deposited (CVD) diamond–coated cutting tools are applied. The tools’ favorable mechanical property profile is based on the hardness of the coating as well as the adaptability of the substrate. Nevertheless, the reproducibility of machining results and process stability are limited by insufficient coating adhesion. The resulting cutting tool failure is based on coating delamination initiated by crack development. By assessing residual stress as an influence of coating adhesion, an analysis of CVD diamond–coated tools is performed using synchrotron X‐ray diffraction in transmission geometry. Investigation of a nanocrystalline and multilayer morphology on cobalt‐based tungsten carbide (WC‐Co) and a silicon nitride–based ceramic (Si3N4) provides the distribution of the principal in‐plane residual stress tensor component σ22 depending on the coating morphology and substrate material. Contrary to microcrystalline CVD diamond, nanocrystalline layers decrease the compressive residual stress. In addition, the CVD diamond coating deposited on the Si3N4 substrate material tends to induce an overall initial tensile residual stress that leads to increased tool performance compared to WC‐Co‐based coated tools. Variation of the coating morphology as well as the substrate material offers the possibility to extend the current model for residual stress–dependent tool failure.
Highlights
Within the field of cutting tool applications, the use of hard cutting materials such as diamond offers an economical machining of difficult-to-cut workpiece materials
The experimentally determined course of the reflection intensities and reflection half-widths, i.e. full width at half maximum (FWHM), as a function of the measurement depth z along the coating thickness sD regarding the multilayer chemical vapor deposited (CVD) diamond coating deposited on WC-5Co substrate is illustrated (Figure 6b)
Based on the presented investigation, varying principal residual stress states were identified in CVD diamond–coated cutting tool specifications
Summary
Within the field of cutting tool applications, the use of hard cutting materials such as diamond offers an economical machining of difficult-to-cut workpiece materials. E. Uhlmann Institute for Machine Tools and Factory Management (IWF) Technische Universität Berlin ments for industrial manufacturing processes within a variety of applications.[2,3] the toughness-related cutting tool behavior reduces the ability to resist stress peaks during challenging machining operations. Uhlmann Department of Production Systems and subsequent failure of the cutting edge occur These tools primarily fail because of the insufficient adhesion between the CVD diamond coating and the cutting tool substrate materials within the substrate–coating interface during their application in various machining processes.[4] the binder phase within the substrate can cause graphitization
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