Synthesis, characterization and in situ Raman detection of Sn3O2(OH)2-xClx phases as intermediates in tin corrosion

Possible intermediates in tin corrosion formed from the chemical reaction between (SnCl2)-Cl-II and NaHCO3 at certain pH levels were characterized. At low pH (Sn21O6)-O-II(OH)(14)Cl-16 was observed. Changing pH to higher-value substitution phases of (Sn3O2)-O-II(OH)(2-x)Cl-x with varying x were obtained. The corrosion behaviour of tin at 80 degrees C and 80% relative humidity was studied using a newly developed Raman cell for in situ measurements. The reaction mechanism on tin surfaces contaminated with NaHCO3 and NaCl was clarified. In the presence of chloride ions, (Sn3O2)-O-II(OH)(2-x)Cl-x and (SnO)-O-II were observed prior the (SnO2)-O-IV formation, whereas (Sn3O2)-O-II(OH)(2) was detected in the absence of chloride. (C) 2015 Elsevier Ltd. All rights reserved.