Ultrahigh Temperature Flash Sintering of Binder-Less Tungsten Carbide within 6 s.

Huaijiu Deng,Jakub Veverka,Monika Vilémová,Mattia Biesuz,Václav Tyrpekl,Milad Kermani,Chunfeng Hu,Salvatore Grasso

doi:10.3390/ma14247655

Abstract

We report on an ultrarapid (6 s) consolidation of binder-less WC using a novel Ultrahigh temperature Flash Sintering (UFS) approach. The UFS technique bridges the gap between electric resistance sintering (≪1 s) and flash spark plasma sintering (20–60 s). Compared to the well-established spark plasma sintering, the proposed approach results in improved energy efficiency with massive energy and time savings while maintaining a comparable relative density (94.6%) and Vickers hardness of 2124 HV. The novelty of this work relies on (i) multiple steps current discharge profile to suit the rapid change of electrical conductivity experienced by the sintering powder, (ii) upgraded low thermal inertia CFC dies and (iii) ultra-high consolidation temperature approaching 2750 °C. Compared to SPS process, the UFS process is highly energy efficient (≈200 times faster and it consumes ≈95% less energy) and it holds the promise of energy efficient and ultrafast consolidation of several conductive refractory compounds.

Highlights

Over the past few decades, ultrafast sintering methods have reached a high degree of sophistication
In the first set of experiments, a sintering process was attempted following the Electrical Resistance Sintering (ERS) procedure [37]. The latter employs an alumina die and copper punches to force the electric current to only flow through the sample (Figure 1a)
Due to the high temperature and heat concentration at the WC/Cu interface the copper punches were partially molten and deformed

Summary

Introduction

Over the past few decades, ultrafast sintering methods have reached a high degree of sophistication. Sintering techniques assisted by the application of an external electric field [4,5,6] allows ultrarapid densification and out-of-equilibrium material processing [7,8,9]. Flash Sintering has been applied to several ceramics with different electrical conductivities: semiconductors [22,23,24], electronic conductors [25,26], ionic conductors [27,28,29], and composites [30,31,32,33].

Results

Conclusion