Enhancing wicking microflows in metallic foams

Metallic foams with high pore density have the potential to be used as highly wicking materials due to the improved capillarity caused by the high porosity and interconnected microchannels. The challenge for using them in their original state lies in their relatively large contact angle. To overcome this, a chemical blackening process for creating a superhydrophilic surface on copper foams is developed. The treatment resulted in a reduction of contact angle from about 91° to almost 0°, indicating a significantly improved wettability. The wicking capacity is further enhanced by controlling the porosity. Rate-of-rise experiments on the treated metal foams with different porosity were conducted. A wicking height of 140 mm in the treated metal foams was achieved compared to no wicking before treatment. A 3-month stability test in a vacuum showed that the contact angle and the wicking performance of the treated copper samples remained unchanged.