The indentation load-size effect (ISE) in Vickers hardness of Al2O3 and Al2O3 + SiC nanocomposites has been investigated using Meyer's law, the proportional specimen resistance (PSR) model and the modified proportional specimen resistance (MPSR) model. The strongest ISE was found for alumina. It is suggested that the smaller ISE in the nanocomposites is associated with the large thermal residual stresses and pre-existing dislocations in these materials, both of which would help the initiation of plastic deformation. Both the PSR and MPSR models described the ISE well, but the MPSR model resulted in slightly lower true hardness values for all materials investigated. There was no evidence of an effect of machining stresses on the ISE.
Information on mechanical properties of human enamel and dentin and effect of load on their deformation and damage tolerance is very important in the development of successful dental materials. In this study, the hardness, indentation modulus and deformation characteristics of tooth have been investigated across the lingual–buccal enamel and dentin cross‐section by instrumented indentation up to 1500‐nm indentation depth. We realized and examined the distribution of hardness and modulus at different areas of enamel and dentin with the aim to understand deformation behaviour at these different locations. Scanning electron microscopy was used for the microstructure characterization of the enamel and dentin and their deformation behaviour. Raman spectroscopy analyses were carried out for determination of the enamel and dentin composition as well. The average values of hardness and modulus for enamel in the occlusal area are 5.35 ± 0.19 and 98.1 ± 1.5 GPa, in the inner area 3.68 ± 0.5 and 81.8 ± 5 GPa and in the area close to the dentin–enamel junction 2.83 ± 0.27 and 71.4 ± 4.1 GPa, respectively. The average values of hardness and modulus of dentin in the area close to the dentin–enamel junction are 0.71 ± 0.05 and 21.27 ± 0.76 GPa and in the inner area 0.65 ± 0.06 and 19.79 ± 0.93 GPa, respectively. The effect of the indentation location on deformation and mechanical properties was clarified.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.