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Mechanical Characterization of ZrB 2 –SiC Composites with Varying SiC Particle Sizes
Author(s) -
Watts Jeremy,
Hilmas Greg,
Fahrenholtz William G.
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2011.04885.x
Subject(s) - materials science , composite material , flexural strength , elastic modulus , particle size , particle (ecology) , ceramic , vickers hardness test , knoop hardness test , indentation hardness , microstructure , chemistry , oceanography , geology
Flexural strength, elastic modulus, and hardness were used to characterize the mechanical properties of ZrB 2 –SiC composites that contained varying SiC particle sizes. Dense ZrB 2 –SiC composites consisting of 70 vol% ZrB 2 and 30 vol% α‐SiC were produced via hot pressing. This series of composites had maximum SiC particle sizes that ranged from 4.4 to 18 μm. The mechanical properties scaled with the maximum SiC particle size, not with ZrB 2 grain size. Flexural strength decreased as the maximum size of SiC particles increased from 1150 MPa at 4.4 μm to 245 MPa at 18 μm with an abrupt decrease in strength at ~11.5 μm. Elastic modulus remained constant at ~530 GPa for compositions containing SiC particles smaller than 11.5 μm, but exhibited a decrease with larger SiC particle sizes. Vickers and Knoop hardness were 21.4 and 17.2 GPa, respectively, for ceramics with SiC particle sizes <11.5 μm, but hardness decreased for larger SiC particle sizes. The decreases in strength, elastic modulus, and hardness with SiC particles larger than 11.5 μm were coincident with stress‐induced microcracking in the composites.