Feasibility Study on Aluminum Under Laser Ablation for Corrosion Resistance in Molten Salt

Fundamental aspects of creating passivation layers for corrosion resistance in nuclear engineering applications, specifically the ability to form complete layers versus porous ones, are being explored in this study. Utilizing a laser ablation technique, 1,064 nm fire at 10 Hz with 60 pulses per shot and 0.5 mm between impact points, aluminum samples are treated in an attempt to create a fully formed passivation layer that will be tested in a LiCl-KCl eutectic salt. By placing these samples into an electrochemical environment mimicking a pyroprocessing system, corrosion rates, resistances and material characteristics are tested for one week and then compared between treated and untreated samples. In initial testing, linear sweep voltammetry indicates corrosion current density for the untreated sample at -0.038 mA center dot cm(-2) and treated samples at -0.024 mA center dot cm(-2) and -0.016 mA center dot cm(-2), respectively. This correlates to a control sample corrosion rate of -0.205 mm center dot yr(-1) and treated rates of -0.130 mm center dot yr(-1) and -0.086 mm center dot yr(-1) for samples 1 and 2. In addition, electrochemical impedance spectroscopy circuits show application of a longer-lasting porous passivation layer on the treated metal, compared to the naturally forming layer. However, the current technique fails to create a uniform protection layer across the sample.