Effects of SiC on phase transformation and microstructure of spark plasma sintered α/β‐SiAlON composite ceramics

Abstract

α/β‐SiAlON/SiC composite ceramic tool materials were prepared via spark plasma sintering. The effects of content and size of SiC particles and sintering temperature on phase composition, mechanical properties, and microstructure were investigated. The results indicated that SiC restrained the transformation of β‐SiAlON to α‐SiAlON, but higher SiC content (≥10 wt.%) resulted in a higher Vickers hardness of the composite. The large size of SiC particles raised the densification temperature of α/β‐SiAlON composites, and small SiC particles benefited to improve microstructure. There were more equiaxed α‐SiAlON grains and β‐SiAlON with a larger aspect ratio (trueα¯95$\bar{\alpha}_{95}$ = 5.1) in the α/β‐SiAlON composite containing 100 nm SiC. The sample containing 10 wt.% 100 nm SiC particles sintered at 1700°C had the optimal properties with a Vickers hardness and fracture toughness of 18.5 ± .2 GPa, 6.4 ± .2 MPa m1/2, respectively.

Cutting performance and wear characteristics of Si3N4–SiCw–HfB2 ceramic cutting tools in turning of ductile cast iron

“…Silicon carbide whisker (SiC w ) possesses several desirable characteristics, such as a high melting point, low density, high strength, wear resistance, and high-temperature oxidation resistance. 19,20 It is typically employed to enhance the toughness of ceramic materials, which addresses the poor toughness and reliability of singlephase ceramic materials. 21,22 Baldacim et al 23 prepared Si 3 N 4 -SiC w ceramics with various SiC w contents by hotpress sintering at 1750 • C. The results indicated that the addition of 20 vol% SiC w resulted in the improvement in fracture toughness, but the high sintering temperature led to β-Si 3 N 4 dominance and a hardness of only 15.52 GPa.…”

“…Silicon carbide whisker (SiC w ) possesses several desirable characteristics, such as a high melting point, low density, high strength, wear resistance, and high‐temperature oxidation resistance 19,20 . It is typically employed to enhance the toughness of ceramic materials, which addresses the poor toughness and reliability of single‐phase ceramic materials 21,22 .…”