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

Purpose and goal

Sandvik Coromant AB and Walter AG are subject to fierce global competition in the cutting tool market. The development of new wear-resistant coating materials is essential in order to maintain competitiveness. The overall purpose of this project is to further develop methods for in-situ hightemperature synchrotron investigations of metastable wear-resistant coatings for cutting tools. The specific aim is to understand the influence of coating post-treatment on the thermal stability and oxidation behaviour of (Al,Ti)N coatings.

Expected effects and result

AlTiN is an excellent new type of CVD (Chemical Vapour Deposition) coating material, showing high hardness and oxidation resistance. However, AlTiN is metastable and may transform to h-AlN and TiN during service temperatures, which degrades its mechanical performance. It is thus of highest importance to be able to prevent this degradation, e.g. by coating post-treatment. By using synchrotron methods, the project can give a knowledge-based design of these new high-performance coatings, instead of having to use trial-and-error methods.

Planned approach and implementation

The project consortium consists of researchers from Sandvik Coromant, Walter and Chalmers. Together they will carry out the project, ranging from materials synthesis, synchrotron experiments, and integrating the results into ongoing R & D at the participating companies. In this project, we will use in-situ high-temperature high-energy grazing incidence transmission synchrotron X-ray diffraction (HT-HE-GIT-XRD) at Petra III to explore the phase transformation of differently post-treated AlTiN coatings deposited on cutting tool inserts.