Mechanical characterization of nacre as an ideal-model for innovative new endoprosthesis materials

Abstract

The increase in fracture toughness of hydrated nacre was not as large as would be expected based on the difference in stiffness of the matrix material after hydration that has been reported. Modulus and toughness were similar to published values and the fracture toughness observed was somewhat higher than reported for alumina implant ceramics, which are in use in total hip arthroplasty. In a direct comparison, we found that a newly developed alumina bioceramic material can in fact match nature in terms of fracture toughness.

Ductile and brittle material removal mechanisms in natural nacre—A model for novel implant materials

“…The average indentation depth was approximately 185 nm, the average elastic modulus was E r = 64.70 ± 3.50 GPa, and the average hardness was H r = 4.41 ± 0.45 GPa. These values are consistent with the results of previous examinations from nanoindentation tests (Menig et al, 2001) and three-point bending tests ((Richter et al, 2010), work in review). It can therefore be assumed that the sample preparation processes did not affect the properties of the material surface.…”

Bendable, Free-Standing Calcite Thin Films

“…Increasing the organic content to 3.2 wt % was shown to nearly double the bending strength. Although the bending strength and bending modulus were lower than the typical values for nacre, − this is the first example of artificial free-standing CaCO 3 films exhibiting bending moduli. We believe that the flexibility and mechanical properties of these films could be further improved through the use of different organic polymers and/or refinement of the processing method to develop their microstructures.…”

“…Both values are significantly lower than is usually observed in natural nacre. − This may be due to the difference of their microstructures. The microstructure motif of nacre consists of layers of brick (oriented plate-like calcium carbonate crystals) and mortar (organic component).…”

“…The thickness was determined by SEM analysis. Data of maximum forces ( P ) and maximum displacements ( Y ) at fracture were used for calculated bending strength (σ max ) and bending modulus ( E ) without compensation …”