Assessing the Potential of Atomic Force Microscopy to Study the Formation of Electrodeposited Calcareous Scales in Uninhibited and Inhibited Conditions

Abstract

Abstract An important feature of cathodic protection in seawater is the formation of calcareous deposits; a term, which is often used to describe magnesium (e.g. Mg(OH)2) and calcium containing (e.g. CaCO3), compounds. Deposition involves the nucleation and growth of minerals on a metallic surface from the interfacial solution, which is supersaturated with respect to certain compounds. Electrodepostion offers a controlled method of generating surface scaling deposits and, as such, there is potential for using electrodeposition to assess the efficiency of scale inhibitors and the rate of nucleation and growth of crystals on solid surfaces. In this study the development of scale on a stainless steel surface through application of a cathodic potential in different brine systems has been used to follow deposition of Ca- and Mg-containing compounds on the surface in uninhibited and inhibited conditions. The focus of this paper is in the potential of atomic force microscopy as a method for assessing the mechanisms and the rate of formation of scale. Some preliminary ex-situ tests were conducted to probe the kinetics of scale formation and the dependence on applied potential. Preliminary tests using in-situ AFM were conducted and some promising results are presented.