Unusual wetting of liquid metals on iron substrate with oxidized surface in reduced atmosphere

The authors found that liquid Cu droplet wetted and spread very widely on a solid substrate of Fe in a reduction atmosphere after the surface oxidation of the substrate. The mechanism of the unusual wetting behavior was investigated by using surface-oxidized Fe substrate with liquid Cu, Ag, Sn and In. It was found that under reduction atmosphere, fine pores were formed at the surface of the substrate which had been oxidized, and that the pores were connected each other continuously over the whole surface. The liquid metals penetrate into those pores by capillary force to cause the unusual wetting behavior.