EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The ever-increasing demands for longer tool life in high-speed machining require multifunctional coatings that display several interlinked characteristics such as high thermal stability, hot hardness and toughness. For this purpose, hard nitride (Ti, Al)N-based nanocomposites coatings have been developed [1–3], but they still suffer from low fracture resistance. In this work, a series of high Al-fraction multilayered TiAlBN nanocomposite coatings deposited by HiPIMS is presented and compared with another TiAlN series (an industrial standard) deposited under the same conditions. The coatings microstructure and compositon were characterized by GDOES, XRD, SEM, TEM, while mechanical properties, including fracture toughness, were tested by room and high temperature nanoindentation and micropillar splitting. TiAlBN coatings exhibit a refined grain structure with individual layer thickness down to 2 nm, which translates into improved fracture toughness over TiAlN while maintaining hardness values up to 40 GPa. In-situ hot-hardness measurements up to 700 ºC and vacuum annealing tests of the coatings up to 1100 ºC were carried out to infer the behavior of the coatings during the intended final cutting application. The results demonstrate the advantages of TiAlBN multilayered coatings over monolayer TiAlN coatings in terms of thermal stability and hardness at all studied temperatures.