Smart wear sensor device based on nanodiamond multilayers

Diamond coated cobalt-cemented tungsten carbide (WC-Co) cutting tools are widely used for machining lightweight engineering parts made of composite materials. Despite the existence of several methods that can monitor the cutting tools' failure, an earlier prediction only about the coating's wear situation before substrate damage is still missing. In this study, the development of a wear sensor prototype based on a nanocrystalline diamond multilayer system is presented. This multilayer system is built up by two conductive nanocrystalline diamond (CNCD) layers and one non-conductive nanocrystalline diamond (NCD) layer in between. Hot-filament chemical vapor deposition (HFCVD) was utilized as coating process for coating the multilayer system onto WC-Co dummy tools, using a gas mixture of methane and hydrogen. The CNCD's specific conductivity is 10 S/cm, whereas NCD's specific conductivity is 5.4 x 10-6 S/cm. The impedances of the prototype in the as-grown state and after some wear losses were measured. A linear response of the impedance to the multilayer's wear situation was detected. A theoretical model was established for simulating the sensor principle qualitatively and calculating its sensitivity quantitatively.

Automated summary

In this study, a wear sensor prototype based on a nanocrystalline diamond multilayer system is developed to quantitatively monitor the wear situation of the coating on cutting tools. The impedance measurement is used to determine the wear level of the coating, and a theoretical model is established to simulate the sensor's working principle.