Incorporation of superconducting MgB2 into plasma electrolytic oxidation coatings on aluminium

Abstract MgB2 particles have been incorporated into a coating formed by AC plasma electrolytic oxidation (PEO) on aluminium under a constant current density. The incorporation of MgB2 into the coating was characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The additions of particles to the electrolyte led to a voltage decrease, possibly a result of the initiation of a “soft” sparking regime. The transition occurred at earlier times with increase of the MgB2 concentration and enhanced MgB2 incorporation into the coating. The coating containing particles was thicker than one in which MgB2 was absent, and had a nodular surface, with MgB2 accumulations in the valleys between the nodules. A superconducting quantum interference device was employed to determine the superconductivity behaviour below about 39 K, the critical temperature of MgB2, and revealed hysteresis in magnetic moment-field curves that typifies a type II superconductor.