posted on 2021-04-15, 14:36authored byZhifei Deng, Ling Li
A bioinspired
study on replicating the superior damage tolerance
of bioceramic composites requires a detailed understanding of the
intrinsic properties of biogenic mineral units. Here, we investigate
and compare the intrinsic properties of biogenic calcite (Atrina rigida) and aragonite (Sinanodonta woodiana) by conducting microbending experiments on the separated prismatic
building blocks. Analyzed bending results indicate that the biogenic
calcite has a higher modulus (36.24 ± 14.4 GPa for A.
rigida vs. 29.9 ± 10.5 GPa for S. woodiana) and strength (446.5 ± 141.5 MPa for A. rigida vs. 338.6 ± 63.2 MPa for S. woodiana) than the
biogenic aragonite, while the nanoindentation results indicate the
opposite trend. Further systematic fractographic analysis suggests
that the biogenic calcite fractures like amorphous glass, while the
biogenic aragonite resembles polycrystalline ceramics. These contradictory
behaviors of biogenic calcite and aragonite under tension-dominated
(microbending) and indentation loading conditions are attributed to
their different intrinsic structures, i.e., intracrystalline organic
inclusions in single-crystal calcite vs. interlocked nanograins in
polycrystalline aragonite.