Qiaoyun Xie
University of Pittsburgh, USA
Title: Dynamic fracture toughness of TAC/CNTS/SIC CMCS prepared by spark plasma sintering
Biography
Biography: Qiaoyun Xie
Abstract
This study focuses on the dynamic fracture toughness of TaC and carbon nanotubes (CNTs) reinforced SiC ceramic matrix composites (CMCs), that prepared by a two-stage spark plasma sintering (SPS) technique. A high densification of 98.4% was achieved under the sintering parameter of 133oC/min, 1800oC and 90 MPa pressure. Vickers indentation was employed to measure the static fracture toughness on the polished surface of ceramic samples; SEM was applied to directly observe the crack propagation after indentation; and split Hopkinson pressure bar (SHPB) was developed to determine the dynamic fracture toughness within the ceramic samples subjected to an impact in a three-point bending configuration. The result indicated that, the dynamic fracture toughness for SiC ceramics was 4.71-8.36 MPa∙m1/2, which was higher that the quasi-static toughness of 3.88 MPa∙m1/2. It was found that SiC ceramics exhibited a more strain rate dependent property for higher strain rate. Fracture toughening mechanisms of CNTs deflection and CNTs bridging were directly observed by SEM.
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