Development of MnO2-incorporated high performance aluminum alloy matrix sacrificial anodes

Abstract

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.

Optimization of Stir Casting Process Parameters for Producing MMC Aluminum Sacrificial Anode Incorporated with Manganese Dioxide Concentrate Powder

“…These findings can be interpreted in the light of interaction thermodynamics between molten aluminum matrix and incorporated oxides, thermodynamic stability of alumina is much higher than that of manganese dioxide which has led to an in-situ metallothermic reduction by aluminum during master alloy processing and master alloy dilution that gave free dissolved manganese in the matrix [39][40]. This result is contradicting with the findings of Shibli et al that showed MnO2 has been incorporated into the matrix without validating nature of inclusion using available characterization techniques [13]. However, the situation is way more different for silica which cannot be easily reduced by aluminum as it needs a temperature of around 1200 o C and holding time of 30-120 minutes to complete the reduction [41], these conditions of Figure 9.…”

“…The reinforcements added to AMMC's to boost their mechanical properties are, and not limited to, SiC ,B4C, BN, TiC, TiB2 , ZrO2, Al2O3, graphite and carbon nanotubes [5][6][7][8]. However, advantages of AMMC's have not been restricted to enhancement of mechanical properties, Shibli et al showed that incorporation of metal-oxides into Al-Zn alloys showed an improvement in its electrochemical properties when used as sacrificial anodes for cathodic protection purposes, several metal-oxides have been implemented for this target like IrO2, CeO2, RuO2, ZnO, Al2O3 and MnO2 [9][10][11][12][13].…”

Nickel Entrapped K10-Montmorillonite Composite Incorporated Al Alloy for Cathodic Protection

“…The inclusion of nano metal oxides and composites synergistically and significantly improves the metallurgical characteristics of anodes [4,11,12]. Recently catalytic activity of Ni nanoparticle has gained significance in many fields.…”