Investigation of the thermal stability of hard coatings by Modulated Temperature Dilatometry

Thermal stability of the hard coatings produced by Physical Vapour Deposition (PVD) technique was investigated by conventional and Modulated Temperature Dilatometry (MT DIL). The state of stresses in the substrate-coating system was monitored by measuring the linear deformation of the specimen using a Linear Variable Displacement Transducer (LVDT). A temperature of investigations was changed between room temperature and maximum 800 °C. It has been confirmed that the measurement resolution relevant to the expected values of the deformation was possible to obtain only with the use of temperature modulation. A significant influence of thin film coating deposition process parameters on the dilatometric response of studied specimens is presented and discussed.