Microstructure and Mechanical Properties of Spark Plasma Sintered Si3N4/WC Ceramic Tools.

Zhenhua Wang,Jiheng Jia,Liyan Cao,Yulin Wang,Ning Sun

doi:10.3390/ma12111868

Abstract

Silicon nitride (Si3N4) based ceramic tools exhibit good machinability in cutting materials such as gray cast iron, ductile iron, malleable cast iron, and superalloys due to excellent high-temperature mechanical properties. In this paper, high-performance Si3N4-based ceramic tools containing tungsten carbide (WC) and cobalt (Co) were studied. Effects of the WC content and Co content on mechanical properties and a microstructure of Si3N4-based ceramic materials were analyzed. Results showed that Si3N4-based ceramic material containing 10 wt % WC and 1 wt % Co had the best comprehensive mechanical properties at a sintering temperature of 1650 °C and holding time of 6 min, achieving Vickers hardness, fracture toughness, and room temperature bending strength of 16.96 GPa, 7.26 MPa·m1/2, and 1132 MPa, respectively. The microstructure of Si3N4-based ceramic tool material is uniform without obvious abnormal growth. The Si3N4-based ceramic tool was mainly composed of α-Si3N4, β-Si3N4, and WC phases.

Highlights

Silicon nitride ceramic materials are widely used in much of the industrial equipment such as cutting tools, gas turbines, thermal insulation materials, and engine parts due to their high strength, high elastic modulus, wear resistance, thermal shock resistance, and creep resistance [1,2,3]
The second phase, which is commonly added to the Si3 N4 -based composite materials, mainly includes the titanium diboride (TiB2 ) [6], titanium carbide (TiC) [7,8], titanium nitride (TiN) [9], Ti (C7 N3 ) [10], silicon carbide (SiC) [11], carbon nanostructure [12], and (W, Ti)C [13], and the like
The masses of the α-Si3 N4 (700 nm), WC (500 nm), Co (500 nm), MgSiN2 (500 nm), Y2 O3 (1 μm), and CeO2 (1 μm) powders were weighed on an electronic balance (WH-BL2003, Weiheng, Guangzhou, China) in proportion, which were placed in a polyurethane ball mill tank and ball milled in a planetary ball mill (QM-3SP2, Nanda, Nanjing, China) with silicon nitride balls for 48 h

Summary

Introduction

Silicon nitride ceramic materials are widely used in much of the industrial equipment such as cutting tools, gas turbines, thermal insulation materials, and engine parts due to their high strength, high elastic modulus, wear resistance, thermal shock resistance, and creep resistance [1,2,3]. Adding a high hardness second phase is an important means to improve the hardness and fracture toughness of silicon nitride ceramics. Tapasztó et al [14] prepared the Si3 N4 -based nanocomposites by hot isostatic pressing sintering (HIP) and spark plasma sintering (SPS) using single- and multi-walled carbon nanotubes (SWCNT and MWCNT), exfoliated graphite (GR), and carbon black (CB) as the reinforcing phases. Their results showed that the comprehensive mechanical properties of the Si3 N4 -based nanocomposites prepared by the two sintering methods were worse than those of the single-phase silicon nitride ceramics without carbon nanostructures.

Methods

Results

Conclusion