AUTHOR=Cao Ting , Li Xiaoqiang , Li Jingmao , Huang Yang , Qu Shengguan , Yang Chao , Liang Liang , Song Tao 

TITLE=Mechanical Properties of WC-Si3N4 Composites With Ultrafine Porous Boron Nitride Nanofiber Additive

JOURNAL=Frontiers in Materials

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2021.534407

DOI=10.3389/fmats.2021.534407

ISSN=2296-8016

ABSTRACT=WC-10 wt.% Si3N4 composites toughened with ultrafine porous boron nitride nanofiber were prepared for the first time by spark plasma sintering. Typically, a second phase or additive is added for hardening or toughening because Young's modulus is a relatively stable property following the rule of mixtures. However, ultrafine porous boron nitride has an additional effect on improving Young's modulus on the composites.The obtained WC-10 wt.% Si3N4 with 0.05 wt.% ultrafine porous boron nitride was found to possess considerably high Young's modulus (779 GPa, which was even higher than densified WC bulk) in addition to good hardness (20.56 ± 0.87 GPa) and fracture toughness (10.57 ± 0.38 MPa•m 1/2 ). In addition, the Si3N4 phase did not exhibit traditional catastrophic fracture as indicated in most investigations. In this study, the peculiar phenomena are discussed, and a probable mechanism is elucidated. It is deduced that the approach of enhancing Young's modulus could be extended to materials with a feature of internal liquid phase during the sintering process and could improve fracture toughness.