Manganese dioxide, a potential catalyst in many electrochemical reactions, was explored as an effective activator in Al ? 5% Zn alloy sacrificial anodes. The catalytic influence of MnO 2 on the anodes was microstructurally and electrochemically characterized using different electrochemical techniques. The process of incorporation of MnO 2 not only improved the grain size but also the galvanic performance of the anodes significantly. A galvanic performance as high as 80% was achieved by incorporating an optimum quantity (0.5%) of MnO 2 in the anode matrix. High and steady active open circuit potential, very low polarization and substantial reduction in self corrosion were achieved during galvanic exposure tests. Effective activation of the anodes by MnO 2 was also revealed by the results of electrochemical impedance analysis. The tolerance to biofouling on the anode surface was studied by quantifying the number of micro-organisms on the anode surface after immersing in natural sea water containing the micro-organisms.

For cathodic protection of steel, the aluminium-zinc alloy sacrificial anodes incorporated with nickel oxide nanoparticles were fabricated. The metallurgical properties of Al-Zn sacrificial anodes enhanced substantially through the infiltration and uniform dispersion of nickel oxide nanoparticles into an Al-Zn matrix. Such effective and uniform presence of nano nickel oxide inside the interior mass of the anodes was characterized by electrochemical techniques. The anodes showed considerably low polarization, steady and high active open circuit potential and substantially decreased self-corrosion during galvanic exposure for prolonged periods. The presence of nickel oxide nanoparticles in the anode matrix caused effective destruction of the passive aluminia film, which facilitated enrichment of galvanic performance of the anode. The anode had high resistance against biofouling also.

Substrates made of steel used in coastal applications are regularly exposed to harsh salty environments; as a result, it is essential to adopt reliable strategies for preventing corrosion. Utilization of aluminum rich sacrificial anodes is an efficient anticorrosive technique owing to its high columbic amplitude, low density, inherent negative potential and galvanic economy. In this work, the electrochemical and micro-structural was characterized by catalytic effect of MnO2-Ni on anode activation. MnO2-Ni present in anode matrix results in destroyed passive alumina film and facilitates the galvanic growth on an anode. The anode exhibited active operating potential and high columbic efficiency during prolonged marine exposure studies. High anodic efficacy was performed by fine tuning composites into the metal matrix Al based alloy. The results revealed that the preferential dissolution of intermetallic particles induced effective sacrificial anode action.

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Nanosized manganese dioxide was prepared by anodic electro deposition method under standardized experimental conditions. Aluminum-zinc alloy sacrificial anodes incorporated with MnO2 nanoparticles were fabricated for cathodic protection of steel. The physico-chemical properties of anodes were enhanced by uniform dispersion and infiltration of the nano-MnO2 particles into the Al-Zn matrix. Such effective and uniform presence of nano-MnO2 inside the interior mass of the anodes was characterized by electrochemical techniques. The anodes exhibited stable potential in open circuit, small polarization and significant rate of depletion in self-corrosion in the course of galvanic immersion studies. The existence of nanocomposite particles in the anode matrix caused effective destruction of the passive aluminia film, which facilitated enrichment of galvanic performance of anode. The anode had better endurance against biofouling also.