SiC表面Ni沉积超疏水膜层的形成机理

Formation mechanism of Ni deposited superhydrophobic film on SiC surface

前期采用环境友好方法制备的改性碳化硅颗粒,经较长时间放置,发现其由亲水性转变为超疏水性,接触角为156°。为解释这一新的现象,采用扫描电子显微镜、能谱、(高分辨)透射电子显微镜、X射线光电子能谱(XPS)对原粉碳化硅、改性后碳化硅及久置碳化硅进行了测试与分析。结果显示:改性后碳化硅经较长时间放置,表面胞状颗粒增大并出现凸起物,粗糙度增加,存在类似于荷叶的微纳米结构。改性后颗粒的主要成分为Ni、Si、O,其中凸起处Ni、O元素的含量明显高于凹陷处。Ni颗粒表面出现清晰的膜层,膜层厚度为2~3 nm,但结晶度偏低。XPS测试结果显示金属镍的特征峰正向移动近4 eV,与镍的氧化态特征峰相一致,从而解释了颗粒表面形态发生细小改变,自发形成超疏水膜层的机理。

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° 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.