Processing, microstructure and mechanical properties of HfB 2 -ZrB 2 -SiC composites: Effect of B 4 C and carbon nanotube reinforcements
Article
Nisar, A, Khan, MM, Bajpai, S et al. (2019). Processing, microstructure and mechanical properties of HfB 2 -ZrB 2 -SiC composites: Effect of B 4 C and carbon nanotube reinforcements
. INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS, 81 111-118. 10.1016/j.ijrmhm.2019.02.014
Nisar, A, Khan, MM, Bajpai, S et al. (2019). Processing, microstructure and mechanical properties of HfB 2 -ZrB 2 -SiC composites: Effect of B 4 C and carbon nanotube reinforcements
. INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS, 81 111-118. 10.1016/j.ijrmhm.2019.02.014
The fully dense HfB 2 -ZrB 2 -SiC composites were processed using spark plasma sintering (SPS) at 1850 °C. The effect of reinforcements (B 4 C and CNT) on the densification as well as mechanical properties were investigated and compared (with monolithic) in the present study. The study showed that the addition of B 4 C and CNT were not only beneficial for the densification but also towards enhancing the mechanical properties (hardness, elastic modulus, and fracture toughness) of HfB 2 -ZrB 2 -SiC composites. The augmentation in the mechanical properties establish the synergy between solid solution formation (with the equimolar composition of HfB 2 /ZrB 2 ) and the reinforcements (SiC, B 4 C, and CNT). The highest increase in the indentation fracture toughness with the reinforcements of B 4 C as well as CNT is >3 times (~13.8 MPam 0.5 when it is 3–4 MPam 0.5 for monolithic ZrB 2 /HfB 2 ) on HfB 2 -ZrB 2 -SiC composites, which is attributed to the crack deflection and pull-out mechanisms. An increase in the analytically quantified interfacial compressive residual stresses in the composites during SPS processing with the synergistic addition of reinforcements (SiC, B 4 C, and CNT) and its effect on the indentation fracture toughness has also been addressed.
