Development of β-SiAlON/12H composite and their cutting performance on Inconel 718 turning

In this study, the development of beta-SiAlON/12H polytype composites for the turning of Inconel 718 was investigated. Various sintering additives, including La2O3, Sm2O3, Y2O3, and their combinations, were used to obtain beta-SiAlON/12H polytype composites. It was found that beta-SiAlON/12H polytype composite with a reasonable amount (12%-14%) of the 12H phase was developed by using La2O3-Y2O3 as codopant and Sm2O3 as a single dopant. The presence of Y2O3 led to a substantial amount of undesired alpha-SiAlON formation due to its smaller cation size. Although adjusting the AlN/Al2O3 ratio in the composition could entirely prevent alpha-SiAlON formation, this approach is only applicable to Sm2O3 dopant due to its larger cation size. beta-SiAlON/12H cutting tools have significantly less flank wear than a commercial beta-SiAlON and quite comparable to Al2O3-SiCw, which is widely used in Inconel 718 turning. No significant differences in cutting performance were observed between cutting tools made of beta-SiAlON/12H obtained by using different dopants.