期刊
ACS NANO
卷 5, 期 4, 页码 3182-3190出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn200319d
关键词
ceramics; silicon nitride; graphene; nanocomposites; fracture toughness
类别
资金
- State of Arizona
- U.S. Office of Naval Research [N000140910928]
- U.S. National Science Foundation [0900188]
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [0954110] Funding Source: National Science Foundation
- Div Of Civil, Mechanical, & Manufact Inn
- Directorate For Engineering [0900188] Funding Source: National Science Foundation
The majority of Work in graphene nanocomposites has focused on polymer matrices. Here we report for the first time the use of graphene to enhance the toughness of bulk silicon nitride ceramics. Ceramics are ideally suited for high temperature applications but suffer from poor toughness. Our approach uses graphene platelets (GPL) that are homogeneously dispersed with silicon nitride particles and densified, at similar to 1650 degrees C, using spark plasma sintering. The sintering parameters are selected to enable the GPL to survive the harsh processing environment, as confirmed by Raman spectroscopy. We find that the ceramic's fracture toughness increases by up to similar to 235% (from similar to 2.8 to similar to 6.6 MPa.m(1/2)) at similar to 1.5% GPL volume fraction. Most interestingly, novel toughening mechanisms were observed that show GPL wrapping and anchoring themselves around individual ceramic grains to resist sheet pullout. The resulting cage-like graphene structures that encapsulate the individual grains were observed to deflect propagating cracks In not just two but three dimensions.
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