Two-step sintering approach for the ex-situ heat treatment of polycrystalline MgB2 coatings

A two-step heating profile is adapted for the sintering of polycrystalline magnesium diboride (MgB2) coatings. The densification process of MgB2 is performed in two isothermal steps. First at 800°C, where diffusion is observed through the presence of coarsened structures. Then at 600°C, where we simultaneously observed densification and grain growth. The length of exposure or the soak period at each isothermal step is crucial to promote densification while limiting the effects of oxidation. Although oxidation is present in the sample subjected to the modified two-step profile, we have shown that it is successful in obtaining a well-packed MgB2 coating.