Smart PVD hard coatings with temperature sensor function

Abstract

In manufacturing technology, the performance of the tools have to conform to increasingly higher standards. Aditionally, recording process data during production is becoming more and more important in the Industrie 4.0. Thin hard tool coatings deposited by physical vapor deposition (PVD) and serving as protection from wear and corrosion are state of the art in manufacturing technology since decades. Integrating additional functions into the coatings will help extend the process limits faced by the load collective in manufacturing technology. One approach here is to exploit the electrical properties of thin coatings to design sensors for temperature measurement. The overall objective of this study is therefore the design PVD sensor coatings. These coatings should facilitate an online measurement of the surface temperature and offer a thermal resistance up to a few hundred degrees centigrade that allows their application in different technical applications. The hard coatings are selected for the two multilayer sensor coatings presented, because they are state of the art as wear protection for numerous manufacturing technology tools. Their temperature sensor function is based on the thermoelectric effect, expected because of the metallic bonding parts of the single coatings. Electrically insulated by Al 2 O 3 , the one material pair consists of CrN/AlN and TiAlN layers. The other material pair consists of a CrAlN and a TiAlN layer. Both sensor coatings show a dense and fine crystalline morphology as well as interlayer without cracks or damages in the SEM crosssection, even between the oxide insulation layer and the nitride sensor layers. Phase stability and oxidation resistance up to at least T ≤ 700 °C are demonstrated for all coating materials. For both sensor coatings, the ability to measure potential differences as a function of the applied temperature is demonstrated. The sensor coating, which in addition to TiAlN consists of a second sensor layer CrN/AlN with nanolaminate architecture, shows a better response behavior and a lower scattering of the measuring values. • Combination of wear protection coatings for multilayer sensor coatings • Temperature measurement by nitridic hard coatings is possible. • Higher temperature measuring accuracy for sensor coating CrN/AlN+TiAlN • Thermal resistivity up to T ≤ 700 °C for developed nitride sensor coatings