One-step electrochemical machining of superhydrophobic surfaces on aluminum substrates

A superhydrophobic surface on an aluminum substrate was fabricated by one-step electrochemical machining using the sodium chloride (NaCl) aqueous solution containing fluoroalkylsilane as the electrolyte. The resulting superhydrophobic surfaces showed a static water contact angle of 166A degrees and a tilting angle of about 1A degrees. The morphological features and chemical compositions were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), electron probe micro-analyzer (EPMA), and Fourier-transform infrared spectrometer (FTIR). It shows that the binary micrometer-nanometer-scale rough structures and the low surface energy coating were present on the aluminum surfaces. The resulting surfaces have good properties of anti-adhesion and self-cleaning. The durability of the superhydrophobic surfaces on aluminum substrates was also investigated. This preparation method is advantageous as it does not require acid electrolyte or a separate process to lower the surface energy, uses simple steps, and is environmental friendly and highly efficient.