Microwave synthesis of duplex α/β-SiAlON ceramic cutting inserts: Modifying m, n, z values, synthesis temperature, and excess Y2O3 synthesis additive
Dongbo Hong, Zengbin Yin, Fuzhou Guo, Juntang Yuan
Abstract
Abstract Duplex α/β-SiAlON ceramic cutting inserts (30α:70β) were synthesized by microwave sintering. The effects of solid solution parameters ( m, n, z ), synthesis temperature, and amount of excess Y 2 O 3 synthesis additive on phase assemblage, microstructure, mechanical properties, and cutting performance were systematically investigated. It was found that increasing m value could improve the formation of α phase while high z value over 1.0 resulted in the dissolution of α phase into β phase and intergranular phase. Increasing the amount of excess Y 2 O 3 could promote densification and elongated β grain growth; however, the excess Y 2 O 3 amount above 4 wt% resulted in substantial crystallization of M’ SS phase, thus declining the mechanical properties and wear resistance. The microwave-synthesized α/β-SiAlON cutting insert with modified parameters ( m = 1.7, n = 1.0, z = 0.7, and 3 wt% excess Y 2 O 3 ) was obtained with optimal comprehensive properties, whose tool life was found to increase by approximately 75% in high-speed milling of Inconel 718 superalloy compared to the commercial α/β-SiAlON cutting insert.