Deposition of ZnSO4 · 3Zn(OH)2· 4H2O films by SILAR method and their study by XRD, SEM and µ-Raman

摘要

ZnSO4·3Zn(OH)2·4H2O(Zinc Sulfate Hidroxide Hidrate) films were obtained on glass substrates by SILAR method. It was employed a precursor solution of ZnSO4and MnSO4 and water near boiling point complexed with 1 ml of NH4OH as a second solution. Films were treated on air at 300oC by 1 hour. Both films ZnSO4·3Zn(OH)2·4H2O as ZnO are important protective against zinc corrosion because they are passive films that give a longer duration to material, it is therefore relevant to study their response to temperature changes. For those reasons films were analyzed before and after thermal treatment to study the structural and morphological changes by X ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman Microscopy techniques. It was found before thermal treatment by XRD the presence of ZnSO4·3Zn(OH)2·4H2O triclinic phase and after such treatment the ZnO hexagonal phase was evidenced. The morphology identified by SEM before thermal treatment was sheets formed by platelet like structure of micrometric size which changes after thermal treatment to a combination of those sheets with flowers like structure characteristic of ZnO hexagonal. By µ-Raman the hexagonal ZnO phase before thermal treatment as the triclinic ZnSO4·3Zn(OH)2·4H2O phase after thermal treatment were confirmed. One objective of this study was to obtain this protective corrosion material in a controlled manner by techiniques of low cost and high simplicity as Silar method. Which, even under temperture increases continue being protective corrosion although suffers phase changes because new phases have protective corrosive characteristics too.