Formation mechanism of Ni deposited superhydrophobic film on SiC surface

The modified SiC particles prepared in the early stage with an environmentally benign method would be changed from hydrophilic to superhydrophobic with a contact angle of 156 degrees after storing for a long time. To explain this new phenomenon, we tested and analyzed original, modified, and previously prepared materials of SiC powder with scanning electron microscope, energy spectrum, (high-resolution) transmission electron microscope, and X-ray photoelectron spectroscopy (XPS). The results showed that after being stored for a long time, the cell-like particles on the surface of SiC particles increased, and the bulges appeared to increase the roughness, which was similar to the micro-nano structures on the surface of lotus leaves. The main components of the modified particles were Ni, Si, and O, and the contents of Ni and O in the bulge were significantly higher than those in the depression. There was a clear film on the surface of Ni particles with a thickness of 2-3 nm, but their crystallinity was relatively low. The XPS test results showed that the characteristic peak of metallic nickel moves forward by nearly 4 eV, which is consistent with the characteristic peak of the nickel oxidation state. Small changes of morphology on particle surface are explained, which in turn explains the mechanism of spontaneous formation of the superhydrophobic film.