Spark plasma sintered ZrC-Mo cermets: Influence of temperature and compaction pressure

摘要

The microstructure analysis and mechanical characterisation were performed on a ZrC-20 wt%Mo cermet that was spark plasma sintered at various temperatures ranging between 1600 and 2100 degrees C under either 50 or 100 MPa of compaction pressure. The composite reached similar to 98% relative density for all experiments with an average grain size between 1 and 3.5 mu m after densification. The nature of SPS technology caused a faster densification rate when higher compaction pressures were applied. The difference in compaction pressures produced different behaviors in densification and grain structure: 1900 degrees C, 100 MPa produced excessive grain growth in ZrC; 1600 degrees C, 50 MPa revealed a very clear ZrC grain structure and Mo diffusion between carbide grains; and 2100 degrees C, 50 MPa exhibited the highest overall mechanical properties due to small clusters of Mo phases across the microstructure. In fact, this particular sintering regime gave the most optimal mechanical values: 2231 HV10 and 5.4 MPa*m(1/2), and 396 GPa Young's modulus. The compaction pressure of SPS played a pivotal role in the composites' properties. A moderate 50 MPa pressure caused all three mechanical properties to increase with increasing sintering temperature. Conversely, a higher 100 MPa pressure caused fracture toughness and Young modulus to decrease with increasing sintering temperature. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.