Microwave synthesis of duplex α/β-SiAlON ceramic cutting inserts: Modifying m, n, z values, synthesis temperature, and excess Y2O3 synthesis additive

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 Y2O3 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 Y2O3 could promote densification and elongated β grain growth; however, the excess Y2O3 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 Y2O3) 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.

High wave transmittance and low thermal conductivity Y– α-SiAlON porous ceramics for high-temperature radome applications

“…Jack and Oyama reported that SiAlON is an electroneutral solid solution formed in the hot-pressing sintering process of Si3N4-Al2O3 [7,8]. Subsequent studies showed that SiAlON ceramics are mainly divided into α-and β-SiAlON based on the differences in the elements and solid solution morphologies [9,10]. The chemical formula of α-SiAlON is MxSi12-(m+n)Alm+nOnN16-n, and metal atoms (M) occupy cell gaps to maintain electricity charge equilibrium.…”

Synthesis of SiAlON‐type compounds by carbothermal reduction and nitridation of nanoparticulate geopolymers

“…Compositionally variable SiAlONs with a wide range of physical and mechanical properties possess advantages over their parent Si 3 N 4 and are achieved by substituting Al and O for Si and N in the SiAlON structure, respectively. [2][3][4][5] In this family, β-SiAlON has a typical chemical composition of Si 6−z Al z O z N 8−z , (where 0 < z < 4.2) and is an attractive phase exhibiting high strength, good thermal-shock resistance as well as oxidation resistance.…”

“…SiAlONs have a wide composition range and several crystal structures, (α, β, O, X, and AlN‐polytypoid phases) and are predominantly solid solutions formed in the quaternary Si 3 N 4 ‐Al 2 O 3 ‐AlN‐SiO 2 system. Compositionally variable SiAlONs with a wide range of physical and mechanical properties possess advantages over their parent Si 3 N 4 and are achieved by substituting Al and O for Si and N in the SiAlON structure, respectively 2–5 . In this family, β‐SiAlON has a typical chemical composition of Si 6− z Al z O z N 8− z , (where 0 < z < 4.2) and is an attractive phase exhibiting high strength, good thermal‐shock resistance as well as oxidation resistance.…”

Effects of Al 2 O 3 –Y 2 O 3 /Yb 2 O 3 additives on microstructures and mechanical properties of silicon nitride ceramics prepared by hot‐pressing sintering

“…Silicon nitride (Si 3 N 4 )‐based ceramics have been attracted much attention because of their wear resistance, corrosion resistance, oxidation resistance, excellent dielectric, and mechanical properties at room as well as elevated temperature environments 1–5 . It has become a potential material in high‐temperature and structural applications, wave‐transparent material such as gas engine parts, cutting tools, heat exchangers, bearings, orthopedic biomaterials, and so on 6–11 . However, Si 3 N 4 is not only a strong covalent compound but also its self‐diffusion coefficient, volume diffusion, and grain boundary diffusion rate during densification are small, so it is difficult to be densified by conventional solid‐state sintering 12 .…”

“…[1][2][3][4][5] It has become a potential material in high-temperature and structural applications, wave-transparent material such as gas engine parts, cutting tools, heat exchangers, bearings, orthopedic biomaterials, and so on. [6][7][8][9][10][11] However, Si 3 N 4 is not only a strong covalent compound but also its self-diffusion coefficient, volume diffusion, and grain boundary diffusion rate during densification are small, so it is difficult to be densified by conventional solid-state sintering. 12 Therefore, the introduction of additives for liquid phase sintering, pressureless sintering, hot-pressing (HP) sintering, gas pressure sintering, spark plasma sintering, and other new technologies to prepare dense Si 3 N 4 ceramics has become a hot research topic.…”