Capillary microflows in porous metals

Capillary flow in the porous media has received a lot of attention due to the applications in many areas, such as oil recovery, irrigation in agriculture, heat pipes and microfluidic pumping. While there have been numerous models to describe the wicking flow behaviour in different porous materials, it received much less attention for open foam porous metals and the flow behaviour is less understood. This paper reports the recent studies on the wicking behaviour of microfluid in treated copper foams with open cell pore structure. We use two types of nano-coated foams as the wicking medium, one of them with a thickness of 2 mm (porosity 96%) and the other with 1 mm thickness (porosity 92%). We treated the surface of the foams to obtain nano-structures, which changed the surface to be super hydrophilic with a near zero contact angle. The wicking experiment show that the wicking in our foams has two stages, with the initial stage of saturated wicking and later the unsaturated wicking. The measured results of wicking heights are presented for the two different foams.