Search

The growth behavior, electronic structures and magnetic properties for NinAl (1-8,12) clusters were investigated detailedly using the selected density functional method (BPW91/LanL2DZ). The change of binding energies show that bimetallic clusters are more stable based on the computed bond energy of Al-Ni, which is bigger than that of Ni-Ni. The strong peaks of Ni5Al in run chart of binding energies, HOMO–LUMO gap, fragmentation energy, the second-order energy and the ionization potential indicate that the stability of bimetallic cluster is optimal when the doping of aluminum is 16.7 atomic percent. At the same time, the hardness analysis of bimetallic clusters shows that Ni5Al cluster has excellent corrosion resistance ability. In addition, the magnetic moment of NinAl (n=1-8,12) clusters decrease obviously comparing with pure nickel clusters because of the s-p-d hybridization between aluminum atom and nickel atom.

The bond length, average binding energy, magnetic moment per atom and the ionic potential of Nin (2-13) clusters were calculated in detail. The variations of magnetic moment per atom and the ionic potential agree well with experimental data. Theoretical results show that BPW91/Lanl2dz method is the best method and basis set for nickel clusters research, respectively. The ground state configurations and electronic structure properties of Nin (2-13) clusters were investigated using the BPW91/LanL2DZ level of DFT method. Through the molecular orbital, we could explain the paramagnetic and diamagnetic to the influence of the magnetic moment after different nickel cluster molecular hybridization.

Theoretical study on the electronic structure of small FemAln(m+n=6) clusters has been carried out at the BPW91 level, and the electronic structures, binding energy and vertical ionization potential of clusters were evaluated. For the stable clusters, the iron atoms gather together and form a maximum of Fe-Fe bonds, and the aluminum atoms locate around Fe core with a maximum of Fe-Al bonds. The binding energy and vertical ionization potential show that the Fe5Al, Fe4Al2 and Fe3Al3 clusters have higher stability, which results provide insight into the properties of iron-aluminides can be obtained from a finite size cluster model.

Sol-gel TiO2 thin films undoped and doped with Ag-ions have been formed on 304ss by dip-coating method respectively. The Ag/TiO2 films are compact and have anatase phase with stable crystal structure and have a thickness of 50 nm approximately. The bactericidal rate of the Ag/TiO2 film against sulfate-reducing bacteria (SRB) strains reaches 97.1% when doping Ag+ with a percentage of 3%. The analysis of potentiodynamic polarization curves illustrates Ag/TiO2 film decreases the corrosion rate obviously.

A uniform TiO2 nanoparticle coating was prepared both on steel and slide glass using sol–gel method and hydrothermal post-treatments. The particle size in the sol was determined to be ～2nm. The surface morphology and the structure of the coatings were analyzed by scanning electron microscope (SEM) and X-ray diffraction（XRD）, which revealed the surface was compact and well-distributed, and the main phase was anatase. UV-VIS spectrophotometer indicated that a absorption peak existed at 340nm. The anticorrosion performances of the coatings in dark and under ultraviolet illumination have been evaluated by electrochemical techniques.

Electrochemical impedance spectrum (EIS) and potentiodynamic polarization curve were applied to invest the corrosive behavior of Fe3Al/ZrO2 composites with different components in marine microbial medium. The results indicated that the existence of microbiology negatively moved the open circle potential. When the composites contained 30% (wt %) ZrO2, the passive film on electrodes surface was the thickest one, even after 25 days the material was still protected. When the content of ZrO2 was 90%, Fe3Al was in the least content, after 25 days the passive film has disappeared, but the material was still not eroded because of the high hardness and corrosion-resistant properties of ZrO2. When the content of ZrO2 was 80%, the passive film was partly damaged, which could lead to more serious local corrosion.

A novel, low-temperature two-step synthesis method for producing BaTiO3 thin films patterned in the form of nanotubes on Ti substrates is reported. Firstly, the Ti substrate is anodized to produce a surface layer of amorphous TiO2 nanotube arrays. Secondly, the anodized substrate is subjected to hydrothermal treatment in aqueous Ba(OH)2, where the nanotube arrays serve as templates for their hydrothermal conversion to single-crystal BaTiO3 thin film. This opens the possibility of tailoring the nanotube arrays and their combinations in the hydrothermal bath, to produce ordered, patterned thin film structures of various Ti containing ceramics.

A novel super-hydrophobic film was prepared by myristic acid (CH3(CH2)12COOH) chemically adsorbed onto the polyethyleneimine (PEI) coated Fe3Al-type intermetallic wafer. The film character and structure were probed with contact angle measurement, scanning electron microscopy (SEM) and atomic force microscope (AFM). The results suggest that the structure of the film is similar to lotus and the seawater contact angle is larger than 150◦. Moreover, the corrosion resistances of untreated and modified samples in seawater were investigated by electrochemical impedance spectroscopy (EIS). Experimental results show that the corrosion rate of Fe3Al-type intermetallic with super-hydrophobic surface decreases dramatically because of its special microstructure.