Reliable in situ measurements of stresses and phase transformations in coatings at high temperatures

Important results from the project

The project was successful: a domed graphite furnace was employed for in situ heating, which enabled the use of lower X-ray energies during measurements and thus, an improved signal-to-noise ratio for the film relative to the substrate. It also allowed for larger collection angles, increasing the collected signal. CVD (Al,Ti)N coatings were annealed in situ at 850 °C and 900 °C, during which both the decomposition of the coatings and the evolution of residual stresses were monitored over time.

Expected long term effects

The project has inspired further development in an ongoing PhD project within the NEXT competence centre. The aim is to develop a setup for in situ high-temperature X-ray nanodiffraction at the NanoMAX beamline at MAX IV in Lund. In X-ray nanodiffraction, a probe size below 100 nm can be achived, enabling both high spatial and temporal resolution during annealing experiments. Since the measurements are performed in transmission geometry, the contribution from the substrate can be minimized.

Approach and implementation

Model CVD coatings were deposited by Walter and Sandvik Coromant. Two beamtime proposals were granted at the P21.2 beamline at PETRA III, Hamburg. A domed furnace was acquired from collaborators. Representatives from all project partners participated at the beamtimes. Following the beamtimes, data evaluation was carried out collaboratively. Complementary X-ray diffraction measurements were performed by Walter and Sandvik Coromant, while electron microscopy analyses were conducted at Chalmers.