Ceramic Cutting Materials and Tools Suitable for Machining High-Temperature Nickel-Based Alloys: A Review

Nickel-based superalloys are attractive to many industrial sectors (automotive, military, energy, aerospace, etc.). However, their physical properties make them difficult to machining using traditional tools. Therefore, new materials for the machining of Ni-based alloys are required. Ceramic-based composites could act as a tool to replace the current materials. The incentives for this paper are to provide an overview of existing ceramic composites and draw some conclusions that will help in solving the problem of choosing materials for the processing of Ni-based superalloys. Despite the diversity of ceramic composites in this work, the possibility of using the SiAlON ceramic for Ni-based alloy machining is highlighted.

Machinability of Nickel-Based Superalloys Using Ceramic Tools

Nickel-based superalloys are attractive to many industrial sectors (automotive, military, energy, aerospace etc.). However, their physical properties make them difficult to machining using traditional tools. Therefore, the new materials for the machining of Ni-based alloys are required. Ceramic-based composites could act as a tool to replace the current materials. The incentives for this paper are to provide an overview of existing ceramic composites and draw some conclusions that will help in solving the problem of choosing materials for processing of Ni-based superalloys. Despite the diversity of ceramic composites in this work the focus was on the SiAlON ceramic.

Microwave sinteringof duplex α/β-SiAlON ceramic cutting inserts: modifying m, n, z values, sintering temperature and excess Y2O3 sintering additive

Duplex α/β-SiAlON ceramic cutting inserts (30α: 70β) were fabricated by microwave sintering. The effects of solid solution parameters (m, n, z), sintering temperature and amount of excess Y2O3 sintering additive on phase assemblage, microstructure, mechanical properties and cutting performance were investigated. It was found that increasing m value could improve the formation of α phase while high z value over 1.0 would lead to the dissolution of α phase into β phase and intergranular phase. Increasing amount of excess Y2O3 could promote densification and elongated β grain growth, but the excess Y2O3 over 4 wt.% would result in substantial crystallization of M'SS phase thus declining the mechanical properties and wear resistance. The microwave-sintered 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 increased by approximately 75% in high-speed milling of Inconel718 superalloy as compared with commercial α/β-SiAlON cutting insert.