Formation of gallium coating on tungsten surface and its oxidation protection in air

To address the poor high-temperature oxidation resistance of tungsten, a new high temperature protective gallium coating (OGa) is designed in this paper. This OGa material is modified with liquid metallic gallium by a mechanical stirring process, and a mixture of GaxOy (Ga2O3 and Ga2O) and Ga is obtained. Not only does it have good flexibility and adhesion, but it can also be easily printed to form a coating on tungsten surfaces. After isothermal oxidation at 800 °C for 24 h, the weight gain of the coating sample is 0.96 mg·cm−2, much lower than that of tungsten. This is attributed to the oxidation of the gallium coating on the tungsten surface to produce a βGa2O3 layer, which prevents oxygen contact with the internal OGa and W substrates. In addition, the inherent flexibility of the intermediate layer of OGa prevents a mismatch in the coefficient of thermal expansion (CTE) between the βGa2O3 layer and the W substrate, ensuring the integrity of the coating. Gallium coatings are expected to be an alternative to conventional protection systems.