Pop-in characteristic induced by nanoindentation in ZrB2-SiC composites

Abstract

In this research, instrumented nanoindentation tests were performed to determine the mechanical properties associated with pop-in events of the ZrB 2 -SiC composites reinforced with and without the mixture of boron nitride nanotubes (BNNTs) and boron nitride nanoplatelets (BNNPs). The results show the sintered ZrB 2 -SiC and (BNNT-BNNP)/(ZrB 2 -SiC) composites have typical pop-in event, and the added mixture of BNNTs-BNNPs increases the critical load at pop-in, initial penetration depth and pop-in excursion at pop-in event. Moreover, the computed shear strength at which pop-in occurs increases with the mixture of BNNTs-BNNPs, which might be ascribed to Orowan-type strengthening effect. The indentation stress-strain curves of these ZrB 2 -SiC composites were also reconstructed. This research is expected to facilitate a better understanding of the microscopic plastic deformation behavior of ZrB 2 and its composites.

Fabrication of high aspect ratio boron nitride nanotube–ZrB₂ composites and the effect of dispersion

“…[15][16][17][18] They can be utilized to overcome the UHTC inherent brittleness, and their mechanical properties can contribute to improved fracture toughness through mechanisms like fiber pullout, crack deflection, and crack bridging. [19][20][21][22][23][24] However, the low oxidation temperature of CNTs (∼400 • C) 25 limits their use in high-temperature application. On the other hand, BNNTs have higher oxidation temperature above 800 • C in air, 22,23,26 which makes them promising for extreme conditions such as hypersonic environments.…”

“…[19][20][21][22][23][24] However, the low oxidation temperature of CNTs (∼400 • C) 25 limits their use in high-temperature application. On the other hand, BNNTs have higher oxidation temperature above 800 • C in air, 22,23,26 which makes them promising for extreme conditions such as hypersonic environments. BNNTs have a structure similar to that of CNTs, with high mechanical strength (∼1.18 TPa), 16 and good chemical and thermal stability, making them attractive nanomaterials for use as fillers in UHTCs.…”