Effect of Iron Substrates on Reduced Porous Morphologies Adequate for Unusual Wetting

The authors have found that liquid metals droplet wetted and spread very widely on solid substrates of Fe in reduced atmosphere after the surface oxidation of the surfaces. This unusual wetting is caused by capillary penetration into porous layer formed on the iron sample that is reduced after oxidized in air. In order to find adequate conditions for the unusual wetting behavior, we have investigated the effect of iron substrate on reduced porous morphology of oxidized iron. Pores in the porous iron layers of all samples with iron substrates are connected 3-dimensionally each other, while those of porous iron films of some samples without substrates were isolated partially and were not connected entirely in the film. Adequate porous iron layers for the unusual wetting were obtained mainly from the condition on the reduction of oxidized iron layer formed on the surface of iron substrates rather than the reduction of oxidized iron film without iron substrates.