2007 Volume 56 Issue 9 Pages 420-426
The mechanism of crystal adhesion and growth of calcium carbonate on the stainless steel plate surface from supersaturated solution was investigated at 25.0ºC. The amorphous CaCO3 (ACC) was immediately precipitated in solution from the highly supersaturated solution. Crystal growth of calcite in solution started after 2 minutes of induction period. The crystal growth of vaterite started at 3.5 min. All the ACC has transformed to crystalline polymorphs by about 8 min. The metastable crystals, vaterite, transformed into stable form, calcite, by 7 hours. When the stainless steel plate was inserted in solution prior to ACC precipitation, ACC adhered at first on the plate surface, then it disappeared within a couple of minutes. After that, the calcite crystals nucleated on the surface and grew to large size. When the plate was inserted in solution just after the precipitation of ACC, vaterite crystals were simultaneously formed with the calcite. The vaterite crystals lined straight on the surface. Calcite crystals gradually grew, whereas the vaterite crystals dissolved and finally disappeared. When the plate was inserted after the growth of vaterite in the solution, no calcium carbonate was formed on the metal surface. Etching of the metal surface by acid reduced the formation of calcite. Scratch on the metal surface scarcely accelerated the adhesion of crystals.
