Fengbin Liu

Superhydrophobic behavior achieved from hydrophilic surfaces

The superhydrophobic behavior of a surface can be generally attributed to the combination of its chemical composition and microscale texture. The surface can be both hydrophobic and rough, and the roughness enhances its hydrophobicity. For a natural or artificial surface, superhydrophobic behavior is generally induced by a structured hydrophobic surface. This paper proposes an alternative; that is the superhydrophobic behavior can be obtained from a structured hydrophilic surface. The superhydrophobic behavior of a T-shape micropillar surface coated with diamond-like carbon has been achieved, which experimentally proved the proposed hypothesis that superhydrophobicity can be created from a hydrophilic surface through surface microstructure modification.

Effects of hydrogen atoms on surface conductivity of diamond film

To investigate the effects of surface chemisorbed hydrogen atoms and hydrogen atoms in the subsurface region of diamond on surface conductivity, models of hydrogen atoms chemisorbed on diamond with (100) orientation and various concentrations of hydrogen atoms in the subsurface layer of the diamond were built. By using the first-principles method based on density functional theory, the equilibrium geometries and densities of states of the models were studied. The results showed that the surface chemisorbed hydrogen alone could not induce high surface conductivity. In addition, isolated hydrogen atoms in the subsurface layer of the diamond prefer to exist at the bond centre site of the C-C bond. However, such a structure would induce deep localized states, which could not improve the surface conductivity. When the hydrogen concentration increases, the C-H-C-H structure and C-3Hbc-C structure in the subsurface region are more stable than other configurations. The former is not beneficial to the increase of ...

Inhibition of the ultrasonic microjet-pits on the carbon steel in the particles-water mixtures

In the incubation period of ultrasonic cavitation, due to the impact of microjets on the material surface, the needle-like microjet-pits are formed. Because the formation of microjet-pits relates with the evolution of cavitation erosion on engineering materials, corresponding study will promote the understanding on the mechanism of cavitation erosion. However, little study on the microjet-pits has been carried out, especially in the particles-water mixture. In this study, we firstly demonstrated the microjet-pits on the carbon steel would be significantly inhibited by Al particles in water. Such inhibition effect indicated that particular particles might not only provide growth sites for cavitation bubbles but also affect the collapse of cavitation bubbles near a solid surface. Our study deepened the understanding on the ultrasonic cavitation erosion in the particles-water mixture.

Formation of the self-assembled structures by the ultrasonic cavitation erosion-corrosion effect on carbon steel

The cavitation erosion-corrosion effect on the metal surface always forms irregular oxide structures. In this study, we reported the formation of regular self-assembled structures of amorphous nanoparticles around the cavitation erosion pits on carbon steel upon the ultrasonic cavitation in methylene blue solution. Each self-assembled structure was composed of linearly aligned nanoparticles of about 100 nm. The formation of self-assembled structures might be due to the combined effect of corrosion, specific sonochemical reaction in methylene blue solution, and the magnetic domain structures on the carbon steel.

Voltammetric and impedance behaviours of surface-treated nano-crystalline diamond film electrodes

The electrochemical performances of hydrogen- and oxygen-terminated nano-crystalline diamond film electrodes were investigated by cyclic voltammetry and AC impedance spectroscopy. In addition, the surface morphologies, phase structures, and chemical states of the two diamond films were analysed by scanning probe microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. The results indicated that the potential window is narrower for the hydrogen-terminated nano-crystalline diamond film than for the oxygen-terminated one. The diamond film resistance and capacitance of oxygen-terminated diamond film are much larger than those of the hydrogen-terminated diamond film, and the polarization resistances and double-layer capacitance corresponding to oxygen-terminated diamond film are both one order of magnitude larger than those corresponding to the hydrogen-terminated diamond film. The electrochemical behaviours of the two diamond film electrodes are discussed.

First Principles Investigation of Water Adsorption on Fe (110) Crystal Surface Containing N

Understanding the interaction of water with iron is crucial to explore the nature of subsequent corrosion of iron-based structural materials. However, because of the lack of the comprehensive understanding about the water behavior on iron surfaces, the detailed knowledge about the role of water in corrosion processes is still unclear. In the process of researches of water adsorption on clean iron surfaces, foreign particle of N is easier brought into the system. In this work, in order to explore water chemistry on the surfaces of the iron containing N, water adsorption on N/ Fe (110) based on first principles calculations are comparatively investigated. Geometry structure and electronic structure are calculated using the method of density functional theory. The calculation results reveal that the existence of N atom has not got the significant changes of the geometry structure of Fe (110)/ H2O interface. And the existence of N atom has not significantly affected the interaction of H2O molecule Fe (110) surface.

Effect of Surface Termination on Electronic Structure of Nano-Crystalline Diamond Film

Hydrogenated and oxygenated nano-crystalline boron-doped diamond (BDD) films were prepared by hydrogen-plasma treatment and boiling in the strong acids, respectively. Surface characteristics of the two diamond films have been investigated by scanning electron microscopy (SEM) and Raman spectroscopy. In order to clarify detailed electronic structures of surface-treated nano-crystalline diamond films, the tunneling current versus voltage (I-V) spectroscopy curves have been measured by scanning probe microscopy (SPM). C 1s core-level spectra and valence band spectra have been also analyzed by X-ray photoelectron spectroscopy (XPS). The characteristics of two types of diamond surfaces are similar. Hydrogen-terminated BDD surface exhibits good conductivity with a narrow band gap. However, the oxygen-terminated one is insulating with a wide band gap. Additionally, there exist surface states in the band gap of the hydrogenated diamond film and no surface states in the band gap of the oxygenated diamond film. Compared with the hydrogen-terminated diamond surface, the surface valence band corresponding to the oxygen-terminated diamond film bends downwards

Effect of Interval Aging Mode on IMC Growth between Low Ag Content Sn-0.3Ag-0.7Cu-0.5Bi-Ni and Cu Substrate

To simulate the application environment of a number of electronic products, the growth of Sn-0.3Ag-0.7Cu-0.5Bi-Ni/Cu solder joints with low content of Ag was investigated during aging in an interval mode. It shows that the intermetallic compound (IMC) (Cu,Ni)6Sn5 layer becomes thicker with increasing aging time. The growth of IMC (Cu,Ni)6Sn5 layer during aging follows the diffusion control mechanism. Furthermore, it is demonstrated that there is no IMC Cu3Sn layer appear whatever increasing the aging time. It is explained the phenomenon is mainly attribute to the interval aging mode. According to kinetics, the activation energy is not high enough to overcome the energy obstacle due to the interval aging mode and finally the Cu3Sn phase doesn’t form. Hence, the reliability of solder joints is improved. Keywords-Sn-0.3Ag-0.7Cu-0.5Bi-Ni solder; intermetallic compound; interval aging; thickness