REDUCTION IN CORROSION SUSCEPTIBILITY OF CAST SILICON BRONZE IN AMMONIA ENVIRONMENT USING ELECTROCHEMICAL POLARIZATION TECHNIQUES

O. I. Sekunowo,, S. I. Durowaye, O. G. Bello

Abstract


Refrigerating systems operating on either the open recirculation or chilled water circuits are prone to corrosion. Often, the ensued corrosion products foul and inhibit effecient heat transfer within the system causing leaks resulting in catastrophic failures. Thus, there is the imperative to search for a material that can be an effective substitute for the conventional copper pipe used in most refrigerating systems.In this study, the corrosion  susceptibility of cast silicon bronze in anhydrous ammonia environment was investigated. The silicon bronze was produced by sand casting with the silicon varied from 1-4 wt.%.An accelerated electrochemical polarisation technique was employed to simulate the corrosion behaviour of the cast alloy. The results show relatively low corrosion susceptibility, 0.75 mm/yr of the
alloy in anhydrous ammonia. This may be attributed to the silicon dioxide (SiO2) passive film formed on the surfaces of the alloy. The effectiveness of the SiO2 passive film increases as the wt. % silicon addition increased. The potential for drastic reduction in maintenance cost and frequency of call-backs of refrigerating units would be enhanced by the outcome of this
study.
Keywords: Refrigerating systems, Electrochemical Polarization, Silicon bronze, Corrosion,
Anhydrous Ammonia


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