Evaluation of the waterproof ability of a hydrophobic nickel micromesh with array-type microholes

Abstract

Hydrophobic nickel micromeshes with array-type circular holes were designed and fabricated, and their waterproof abilities with respect to the hole diameter were theoretically and experimentally evaluated. The hole diameter increased from 20 µm to 100 µm in steps of 10 µm, while the hole pitch was fixed at 200 µm. Photolithography and nickel electroforming processes were used to fabricate 10 µm thick nickel micromeshes. In order to enhance the waterproof ability of nickel micromeshes, a plasma-polymerized fluorocarbon (PPFC) layer was coated on the nickel micromeshes. The contact angle of the micromesh increased from 63° for the non-coated nickel flat film to 106° for the PPFC-coated film. The maximum allowable hydraulic pressure decreased as the hole size increased and was inversely proportional to the hole diameter. The micromesh with a hole diameter of 20 µm showed the highest waterproof performance, with a water height of 111 cm in the experiment. The measured maximum allowable hydraulic pressures were about 31% lower than the calculated pressures on average.