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Mechanical Properties and Microstructure of Ca 2 SiO 4 –CaZrO 3 Composites
Author(s) -
Hou Tien I,
Kriven Waltraud M.
Publication year - 1994
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.1151-2916.1994.tb06958.x
Subject(s) - materials science , microstructure , composite material , monoclinic crystal system , calcium silicate , fracture toughness , silicate , phase (matter) , grain size , mineralogy , chemical engineering , crystallography , crystal structure , chemistry , engineering , organic chemistry
Three types of dicalcium silicate (Ca 2 SiO 4 –calcium zirconate (CaZrO 3 ) composites were fabricated and their microstructures correlated with their mechanical properties. In the first type, Ca 2 SiO 4 was added as a minor phase. The second type consisted of a 50 vol% Ca 2 SiO 4 ‐50 vol% CaZrO 3 mixture, while in the third type, CaZrO 3 constituted the minor phase. Pure CaZrO 3 was also studied as a control and found to have a toughness which depended on its grain size. In composites with Ca 2 SiO 4 as the minor phase, a toughness increase was observed and found to be a function of matrix grain size. The composite with the second type of microstructure had the highest toughness of about 4.0 Mpa. m 1/2 , which was about double that of the monolithic CaZrO 3 . No evidence was found for transformation toughening by the orthorhombic (β) to monoclinic (γ) transformation in Ca 2 SiO 4 . The main toughening mechanisms identified were crack deflection and crack branching. Microstructural observations indicated the existence of weak grain boundaries in CaZrO 3 agglomerates as well as weak interfaces between the two phases.