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Cathodic protection is widely recognized as the most cost effective and technically appropriate corrosion prevention methodology for the port, offshore structures, ships. When applying the cathodic protection method to metal facilities in seawater, on the surface of the metal facilities a compound of calcium carbonate(CaCO 3 ) or magnesium hydroxide(Mg(OH) 2 ) films are formed by Ca 2+ and Mg 2+ ions among the many ionic components dissolving in the seawater. And calcareous deposit films such as CaCO 3 and Mg(OH) 2 etc. are formed by the surface of the steel product. These calcareous deposit film functions as a barrier against the corrosive environment, leading to a decrease in current demand. On the other hand, the general calcareous deposit film is a compound like ceramics. Therefore, there may be some problems such as weaker adhesive power and the longer time of film formation uniting with the base metal. In this study, we tried to determine and control the optimal condition through applying the principle of cathodic current process to form calcareous deposit film of uniform and compact on steel plate. The quantity of precipitates was analyzed, and both the morphology, component and crystal structure were analyzed as well through SEM, EDS and XRD. And based on the previous analysis, it was elucidated mechanism of calcareous deposit film formed in the sacrificial anode type (Al, Zn) and current density (1, 3, 5 A/m 2 ) conditions. In addition, the taping test was performed to evaluate the adhesion.

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Gallium antimonide (GaSb) has an extremely high electron mobility and an excellent lattice match with various III–V ternary and quaternary compounds. In this study, the effect of wet-etching processes on the GaSb (001) surface was investigated, with a focus on the effect of H2O2. Dilution with H2O and addition of H2O2 in HF/H2O2/H2O, NH4OH/H2O2/H2O, and HCl/H2O2/H2O mixtures produced different effects on the GaSb surface. The etching rate of GaSb increased with a high dilution ratio and a small amount of H2O2 in the mixture of NH4OH/H2O2/H2O. The addition of H2O2 in H2O decreased GaSb oxide thickness and increased the contact angle on the GaSb surface and the XPS Ga 3d and Sb 3d3/2 peak area ratios of Ga2O3/GaSb and Sb2O3/GaSb, which strongly imply that the H2O2 in the wet-etching solution served as an inhibitor of surface oxidation on GaSb. On the basis of the observed etching rates of GaSb, oxidation kinetics, contact angles, and chemical states, it is suggested that concurrent oxidation of GaSb and etching of oxidized GaSb occur on the GaSb surface in the presence of H2O2. Furthermore, the overall kinetics is determined by the relative amount of H2O2, which depends on the pH of the etching solution.

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