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

Aluminium oxynitride has unique thermal and chemical stability that makes it a perfect candidate for a wide range of applications. Currently commercially available aluminium oxynitrides exhibit average grain size in the order of 150–200 μm; however, development of new methods to control grain size, especially, at the nano-scale could create materials with improved properties. The most promising techniques for aluminium oxynitride preparation are hot pressing (HP), hot isostatic pressing (HIP) and spark plasma sintering (SPS). The aim of our research is a preparation of cheap Al2O3/AlN by eco-friendly technology towards aluminium oxynitride processing. The oxidization of base AlN powder with specific surface area 4.0 -8.0 m2/g and an average particle size of 0.80 -1.8 μm for 3, 6 and 10h at 900°C in air atmosphere was the first step. Hot isostatic pressing for 5h at 1700°C in nitrogen was used for sintering of oxidized powders. The increasing the oxidation time significantly improved the tensile strength of sintered samples compared to the reference. In the case of reference AlN, the measured value was 13.8 MPa on average for the 4-point bending test and 159.2 MPa after 10 h oxidation. IThe oxidation time has influence not only on mechanical properties. We showed, that the increasing of oxidizing time, the higher density, the lower porosity can be achieved after 10h oxidization.