A Processing–Microstructure Correlation in ZrB2–SiC Composites Hot-pressed under a Load of 10 MPa
Year: 2015
Type: article
Abstract: Monolithic ZrB2 ceramic and its composites, with 5 to 30 vol. % SiC, has been prepared by hot pressing at temperatures of 1700, 1850 and 2000℃, for 30 minutes under relatively low pressure of 10 MPa. Densification behavior of ZrB2-based composites is improved by the addition of SiC particulates. The fracture surface of monolithic ZrB2 ceramics shows a grained structure, with faceted ZrB2 grains, as the fracture appears to spread prevalently along an intergranular path. The ZrB2/ZrB2 boundary interface is seemingly free of any secondary phases. The microstructure of ZrB2–30 vol. % SiC composite, hot-pressed at 1700℃, is consistent with measured porosity for the sample that has ~8% open pores, nearly without closed pores. It seems that mechanical interlocking between ZrB2 and SiC is an important mechanism for densification. In the microstructure of specimens consolidated at 1850℃, neck formation between ZrB2 particles is visible. In contrast, relatively fully dense samples are obtained by hot-pressing at 2000℃. Intergranular SiC particles inside ZrB2 grains show the occurrence of mass transfer among ZrB2 particles, which in effect brings the elimination of pores to a fortunate ending. Efficient mixing of starting powders is very critical in order to achieve a fine-grained homogenous microstructure.
Institution: University of Tabriz
Language: English
Subfield: Ceramics and Composites
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
Funder: University of Tabriz
OpenAlex ID: W2152250087