Corrosion Behavior of B_4C/6061Al Neutron Absorber Composite in Different H_3BO_3 Concentration Solutions

摘要

In this study, electrochemical corrosion tests, full-soak corrosion tests and associated microstructure analysis were conducted to investigate the corrosion behaviors of B_4C/6061Al neutron absorber composites(NACs) manufactured by powder metallurgy method in solutions having different boric acid(H_3BO_3) concentrations(500, 2500 and 10,000 ppm). In electrochemical corrosion tests, B_4C/6061Al NACs demonstrate the highest(short-term) corrosion resistance in the 2500 ppm H_3BO_3 solution. While for full-soak corrosion tests, the B_4C/6061Al NACs show the highest(long-term) corrosion resistance in the 500 ppm H_3BO_3 solution. This difference is found to be mainly due to the formation of different surface morphologies during these two different corrosion tests. As noticed, a layer of Al(OH)_3was formed on the composite surface during full-soak corrosion tests, but it cannot be found in the electrochemical corrosion tests. The full-soak corrosion mechanism of the B_4C/6061Al NACs in the H_3BO_3 solution is found to be primarily determined by the dynamic balance between the formation and dissolution rates of the oxide film, which is mainly controlled by the density of H^+ ions in the solution.