Electrodeposition of Oriented SrCO[sub 3] Coatings on Stainless Steel Substrates

Abstract

Cathodic reduction of a strontium bicarbonate bath stabilized by a variety of amine-carboxylic acids as ligands resulted in the deposition of micrometers-thick SrCO3 coatings by electrogeneration of base. The use of diethylenetriaminepentaacetic acid (DTPA) yielded SrCO3 coatings with a distinct c-axis orientation. The degree of orientation is higher in thick rather than thin coatings. The degree of orientation is also reduced when the DTPA concentration is increased or the pH is increased. These observations suggest that oriented crystal growth is due neither to the template effect of the substrate nor any additive mediated interaction due to DTPA but is solely due to the kinetics of crystallization. The Sr[DTPA] complex has the highest stability constant among the ligands studied, indicating the low degree of supersaturation in this bath compared to those stabilized by other complexing agents. SrCO3 deposition is a good model for the study of aragonite CaCO3 deposition by virtue of being isostructural with the latter and having the smallest lattice mismatch with aragonite among the heavier metal carbonates. (C) 2006 The Electrochemical Society.