Microstructure and Properties of Ultrafine Cemented Carbides Prepared by Microwave Sintering of Nanocomposites

Yanju Qian,Zhiwei Zhao

doi:10.3390/cryst10060507

Abstract

Ultrafine cemented carbides were prepared by microwave sintering, using WC-V8C7-Cr3C2-Co nanocomposites as a raw material. The effects of sintering temperature and holding time on the microstructure and mechanical properties of cemented carbides were studied. The results show that the ultrafine cemented carbides prepared at 1300 °C for 60 min have good mechanical properties and a good microstructure. The relative density, Vickers hardness, and fracture toughness of the specimen reach the maximum values of 99.79%, 1842 kg/mm2 and 12.6 MPa·m1/2, respectively. Tungsten carbide (WC) grains are fine and uniformly distributed, with an average grain size of 300–500 nm. The combination of nanocomposites, secondary pressing, and microwave sintering can significantly reduce the sintering temperature and inhibit the growth of WC grains, thus producing superfine cemented carbides with good microstructure and mechanical properties.

Highlights

Cemented carbides are one of the most widespread powder metallurgy products worldwide.The reason for this is that, compared with other cutting materials, they have an excellent combination of hardness and toughness [1,2]
Some studies have shown that when the content of Co-phase is constant and when the WC grain size reaches ultrafine or nanocrystalline, the hardness and toughness of cemented carbides are improved [5,6]
When the WC grain size is less than 500 nm, the hardness and toughness of the cemented carbides are greatly improved

Summary

Introduction

Cemented carbides are one of the most widespread powder metallurgy products worldwide. The reason for this is that, compared with other cutting materials (such as diamond or high-speed steel), they have an excellent combination of hardness and toughness [1,2]. Some studies have shown that when the content of Co-phase is constant and when the WC grain size reaches ultrafine or nanocrystalline, the hardness and toughness of cemented carbides are improved [5,6]. The development of ultrafine or nanocrystalline cemented carbides with high hardness and high strength has become a key research issue among those working with cemented carbide materials [7]

Methods

Results

Conclusion