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

Abstract

The authors have found that liquid metal droplets wetted and spread very widely on solid iron substrates in a reducing atmosphere after the surface oxidation of the specimens. This unusual wetting is caused by capillary penetration into the porous layer formed on the iron sample that is reduced after first being oxidized in air. In order to find adequate conditions for the unusual wetting behavior, the effect of the underlying iron substrate on the reduced porous morphology of the oxidized Fe layer has been investigated. Pores in the porous iron layers of all samples formed on iron substrates are 3-dimensionally inter-connected, while those of the porous iron films of some samples without underlying iron substrates were partially isolated and not entirely connected within the films. Adequate porous iron layers that show this unusual wetting behavior were obtained mainly from reduction of the oxidized iron layer formed on the surface of iron substrates rather than from reduction of the oxidized iron films formed without underlying iron substrates.