Substrate effect on surface adhesion/crystallisation of calcium carbonate

The work reported primarily focuses on understanding the mechanisms of calcium carbonate (CaCO3) scale deposition on nano- and micro-structured polymer surfaces and on stainless steel surfaces treated with commercially available industrial coatings, taking untreated stainless steel as a reference substrate. The effect that a substrate's surface has on the deposition and growth of CaCO3 crystals in terms of its physical and chemical parameters is explored. In addition, substrate effects on crystal morphology are examined as the nature of the substrate is clearly shown to influence the prominent polymorph in CaCO3 deposition. Also, the adhesion of CaCO3 to a surface is affected by the mechanism of deposition and this is assessed by whether crystals migrated from the bulk solution to settle on the surface or heterogeneously nucleate on the surface itself and subsequently grow there. The work provides evidence that the surfaces are acting as nucleation sites for crystals to heterogeneously initiate and grow and is also a demonstration of crystals growing in confinement.

► Surface energy and roughness cannot predict surface scaling tendency directly.
► Surfaces that prevent particulate deposition are ineffective anti-scaling surfaces.
► Higher adhesion exists between scale and substrate when crystals grow from surface.