Investigation on the corrosion and wear of magnesium alloys reinforced with hard materials

摘要

Uniform introduction of hard material particles into a magnesium surface has been achieved during dispersion by plasma-arc powder weld surfacing with alternating current. Uncontrolled extinction of the arc has been largely avoided with an appropriate modification of the inert gas nozzle. Polarisation of carbide-reinforced magnesium samples in a 3% sodium chloride solution results in pitting-type corrosion. Current-density vs. potential curves show current increases at more positive potentials in the case of reinforced samples in sodium sulphate solution. In 0.01 N sodium hydroxide solution, the carbide-reinforced samples are less resistant. In this case, dissolution of the material already occurs from -500 mV [SCE] in the zone surrounding the carbide particles. Moreover, an attempt has been made to improve the properties by weld surfacing of the wrought magnesium alloy AZ31B with NiBSi/WSC; however, it was not possible to achieve sufficient bond strength. The wear resistance of the samples is excellent. After subjecting to the Miller test, the abrasive loss from samples reinforced with silicon carbide is very low, with values between 1 and 1.5%. In comparison with magnesium alloy AM50 which has not been reinforced, the abrasive loss from the reinforced samples is lower by a factor of 25. These results have been also confirmed by investigations in the abrasion test vessel.