Toughening effect of short carbon fibers in the ZrB2-ZrSi2 ceramic composites

The toughening effect of the short carbon fibers in the ZrB2-ZrSi2 ceramic composites were investigated, where the ZrB2-ZrSi2 ceramics without carbon fibers were used as the reference. The mechanical properties were evaluated by means of flexural and SENB tests, respectively. The microstructure was characterized by SEM equipped with EDS. The results found that the short carbon fibers were uniformly incorporated in the ZrB2-ZrSi2 matrix and the relative density was about 97.92%. The flexural strength of short carbon fiber-reinforced ZrB2-ZrSi2 composites is 437 MPa; the fracture toughness and the work of fracture are 6.89 MPa m(1/2) and 259 J/m(2), respectively, which increased significantly in comparing with composites without fibers. The microstructure analysis revealed that the improved fracture toughness could be attributed to the fiber bridging, the fiber-matrix interface debonding and the fiber pullout, which consumed more fracture energy during the fracture process. (C) 2015 Elsevier Ltd. All rights reserved.