Corrosion and oxidation behaviour of B-SiAlON via different processing route

The corrosion resistance of B-SiAlON based advanced ceramic materials in molten aluminum, equimolar NaCl-KCl melt and also in the melted mixture of NaF and AlF3 (molar ratio: 1:1.163) were investigated. two kinds of B-SiAlON were tested: B-SiAlON prepared from powder precursor produced by carbothermal reduction and nitridation (CRN) of pyrophyllite and B-SiAlON made from commercila powders (AlN, Al2O3 and Si3N4). Corrosion tests were realized at 760°C for 7, 36 and 72 h under nitrogen atmosphere by dip finger test method. All types of B-SiAlON have great corrosion resistance against molten aluminium and NaCl-KCl melt at these conditions. The results of corrosion test were different for the B-SiAlONs in the in molten fluorides. While the corroded zone was only 100µm deep after 72 h corrosion test in reference B-SiAlON prepared from synthetic powders /SiAlON-R), in sample prepared from CNR pyrophyllite (SiAlON-P) it was almost 230 µm thick. Additionally, the oxidation resistance of B-SiAlON was tested. The results showed that both SiAlON-P and reference SiAlON-R have comparable good oxidation resistance.