Comment on “Wetting of liquid copper on TC4 titanium alloy and 304 stainless-steel at 1273–1433 K” Materials & design 169 (2019) 107667

In the present paper a few comments on the paper "Wetting of liquid copper on TC4 titanium alloy and 304 stainless-steel at 1273–1433 K" Materials & Design 169 (2019) 107667, have been discussed. The comments are mainly focused on the wetting mechanism. We used the ISD method for characterization of the intrinsic wetting behavior of molten Cu on 304ss. In Sun et al.'s work, they adopt MSD method for characterization. With this respect the obtained data and discussed results are doubtful. For the wetting behavior characterization of metal/metal system, oxide film is a non-negligible factor on both the droplet surface and the substrate surface. To characterize the intrinsic wetting behavior, it is necessary to avoid the involvements of de-oxidation process and the influence of melting process.