Cold densification and sintering of nanovaterite by pressing with water

Abstract

While dissolution-precipitation, plastic deformation and fracture have been proposed to explain the compaction of carbonates in geological formations, the role of these mechanisms on the densification process of calcium carbonate nanoparticles in synthetic systems remains poorly understood. Here, we systematically investigate the effect of pH of the aqueous phase (1 ≤ pH ≤ 7), temperature (10 ≤ T ≤ 90 °C), and pressure (10 ≤ P ≤ 800 MPa) on the cold compaction of nanovaterite powder with water to shed light on the mechanisms underlying this unique densification. Compaction experiments reveal that the applied pressure plays a major role on the densification of vaterite nanopowder with water. Our experimental data thus suggest that plastic deformation or subcritical crack growth might be important densification mechanisms for vaterite nanoparticles. These findings provide a new perspective into the cold compaction of nanopowders with water and may open promising routes for the manufacturing of CO2-based structural materials at mild processing conditions.