ELECTROSPARK DEPOSITED COATING TECHNOLOGY FOR NAVAL APPLICATIONS

摘要

Evaluation of the electrospark deposition (ESD) process suggests that this is a viable in-situmethod for repairing small worn and corroded areas on nickel- and copper-base alloys. Metallographicanalysis showed metallurgically bonded ESD coatings with no interconnected porosity andmicrocracking through the coating to the substrate. Microhardness measurements made on ESD Alloy400 indicated uniformity in microhardness across the coating as well as within the Alloy K500 substrate,substantiating the premise that the ESD process does not alter the microstructure of the base material.Potentiodynamic polarization testing of ESD Alloy 400 and 70/30 copper-nickel showed excellentcorrelation between the ESD coatings and similar wrought alloys. Crevice corrosion testing of ESDAlloys 625, 59, and C276 indicated no susceptibility for ESD Alloy 59 after 365 days’ seawaterimmersion. ESD Alloys 625 and C276 were susceptible to crevice corrosion, with maximum depths ofattack of 0.011 in. (0.28 mm) and 0.009 in. (0.22 mm), respectively.