Estimation of Corrosion Potential of Aluminium Brazing Fillets Using Area Method

Abstract

<div class="section abstract"><div class="htmlview paragraph">Open Circuit Potential (OCP) is the potential established between the working electrode (the metallic surface to be studied) and the environment, with respect to a reference electrode, which will be placed in the electrolyte close to the working electrode. It is very important to measure the electric potentials of various metallic materials in order to know their corrosion behavior in various environments. But perhaps if there is brazing joint involved, as in the case of aluminium heat exchanger components, there are some challenges involved in knowing the potential of the fillet part which includes the selective masking of the areas within the same sample for testing. Firstly, getting reliable & accurate data due to masking process is one concern. Secondly, about the aluminium heat exchanger sample, the variation in OCP values within a single sample are possible due to various factors i.e. presence of cladding on the surface of the materials, presence of sacrificial Zn coating on the microtubes, variation in brazing parameters etc.</div><div class="htmlview paragraph">In this study analytical correlation is made to OCP values of individual postbrazed child part samples w.r.t the entire brazed joint sample. This is being done in order to calculate & estimate the electric potential of the brazing fillet part. The individual currents at various areas within the sample w.r.t total specimen area are calculated & evaluated in order to arrive at a correlation between the observed potential vs. the sample area. From the obtained results it was found that the predicted theoretical fillet potential was in close agreement with the measured value. However, there is a scope of improvement in refining the simulation methods used in this study, in order to obtain more repeatable & accurate measurement OCP values.</div></div>