Open AccessBeneficial effect of low BN additive on densification and mechanical properties of hot-pressed ZrB2–SiC composites
Author(s) -
Saber Haghgooye Shafagh,
Shapour Jafargholinejad,
Siyamak Javadian
Publication year - 2021
Publication title -
synthesis and sintering
Language(s) - English
Resource type - Journals
eISSN - 2564-0194
pISSN - 2564-0186
DOI - 10.53063/synsint.2021.1224
Subject(s) - materials science , vickers hardness test , composite material , fracture toughness , composite number , scanning electron microscope , porosity , relative density , hot pressing , microstructure
The incorporation of 1 wt% hexagonal BN (hBN) into ZrB2–30 vol% SiC could noticeably better the fracture toughness, hardness, and consolidation behavior of this composite. This research intended to scrutinize the effects of various amounts of hBN (0–5 wt%) on different characteristics of ZrB2–SiC materials. The hot-pressing method under 10 MPa at 1900 °C for 120 min was employed to sinter all designed specimens. Afterward, the as-sintered samples were characterized using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and Vickers technique. The hBN addition up to 1 wt% improved relative density, leading to a near fully dense sample; however, the incorporation of 5 wt% of such an additive led to a composite containing more than 5% remaining porosity. The highest Vickers hardness of 23.8 GPa and fracture toughness of 5.7 MPa.m1/2 were secured for the sample introduced by only 1 wt% hBN. Ultimately, breaking large SiC grains, crack bridging, crack deflection, crack branching, and crack arresting were introduced as the chief toughening mechanisms in the ZrB2–SiC–hBN system.