Role of Compactness on Hardness and Reduced Modulus of Vaterite Determined with Nanoindentation

The influence of compaction degree of synthetic vaterite, the metastable polymorph of calcium carbonate, on determined mechanical properties was investigated using nanoindentation instrument. Specimens for measurements were prepared as pressed pellets with the application of three different forces—40, 60 and 80 kN. The highest values of reduced modulus and hardness were detected for vateritic pellet pressed at 60 kN. For this specimen, reduced modulus and hardness were found to be in ranges 74–10 and 5.2–0.3 GPa, respectively. Observation with scanning electron microscope showed increase compactness of pellet’s microstructure and an increase in density and length of microcracks within vateritic pellets when higher pressing force was applied.