Superior anti-oxidation performance of Ga-Al alloy on tungsten wire based on in-situ induced self-healing mechanism

The service life of tungsten wires in an atmospheric environment is not ideal since the tungsten wires were prone to oxidation when electrified in the air. As a novel coating material to fabricate high-temperature anti-oxidation coatings on the surface of tungsten wires, liquid gallium-aluminum alloy (Ga-Al) was developed by the simple method of melting metallic gallium and aluminum foil. After a brief period of electrical heating, an outer layer of Al2O3 was generated by the oxidation of Ga-Al alloy coating, and finally formed a bilayer composite coating containing Al2O3 and liquid metallic Ga-Al on the surface of tungsten wire. The outer Al2O3 layer not only effectively prevents the tungsten wire from oxidation, but also ensures the secure containment of the internal Ga-Al liquid metal. The inner layer of liquid metallic Ga-Al effectively solves the mismatch in the coefficient of thermal expansion (CTE) between Al2O3 and the substrate, significantly enhancing the integrity of the coating. Besides, the internal can regenerate a new protective Ga2O3 cover based on the self-healing mechanism of liquid metal, even when the outer Al2O3 layer fractures. Consequently, the Ga-Al composite coating significantly prolongs the service life of tungsten wires from 16 min to more than 24 h in an atmospheric environment. The efficient dual antioxidant strategy, namely the formed Al2O3 layer and the self-healing Ga-Al liquid metal, was first proposed as a novel approach to prevent the oxidation of tungsten wires.