A stannate chemical conversion process followed by an activation procedure was employed as the pre-treatment process for AZ91D magnesium alloy substrate. Zn was electroplated onto the pre-treated AZ91D magnesium alloy surface from pyrophosphate bath to improve the corrosion resistance and the solderability. The surface morphologies of conversion coating and zinc coating were examined with scanning electron microscope (SEM). The phase composition of conversion coating was investigated by X-ray diffraction (XRD). The electrochemical corrosion behavior of the coatings in the corrosive solution was investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The experimental results showed that the activated stannate chemical conversion coating provided a suitable interface between zinc coating and the AZ91D magnesium alloy substrate. The corrosion resistance of the AZ91D substrate was improved by the zinc coating.

The present paper is a report on sol-gel synthesis of crystalline magnesium oxide on NdFeB magnet, using nonalkoxide precursor chemicals and additive of collodion as template. The decomposition of the precursor and subsequent formation of MgO film on NdFeB magnet was simulated by flow chart which is confirmed by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and theoretical calculation. X-ray diffraction analysis pointes out that the phases present at 350uC is periclase MgO and the crystallite size of MgO grows as the heat treatment temperature increases. The formation process of MgO is verified by FTIR. The component of film on the NdFeB magnet is mainly magnesium oxide, which is also well crystallised and transparent. The corrosion tests indicate that the film is anticorrosion for NdFeB magnet.

Anti-corrosive composite cerium oxide/titanium oxide (CeO 2 / TiO 2 ) thin films were successfully prepared on an AZ91D magnesium alloy substrate by applying cerium oxide (CeO 2 ) thin films as the inner layer with a sol-gel process. Composition and surface morphology of the thin films were analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD showed that the composite films consisted of cerianite and anatase phases. The wettability of the thin films was evaluated by water contact angles measurements. Potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) tests were used to evaluate the corrosion behavior of the bare substrate and coated samples in 3.5 wt% sodium chloride solution (3.5 wt% NaCl). The results demonstrated that titanium oxide (TiO 2 ) thin film mainly dominated the corrosion resistance of samples and the composite films with excellent hydrophilicity could significantly improve the corrosion resistance of AZ91D magnesium alloy.

：Amorphous Ge-doped HfO x films have been deposited on p-Si(100) substrates by means of RF magnetron sputtering. Microstructural investigations reveal the partial oxidation of doped Ge atoms in the amorphous HfO x matrix and the existence of HfSiO x interfacial layer. Capacitance-voltage hysteresis of the Ag/ Ge-doped HfO x /Si/Ag memory capacitor exhibits a memory window of 3.15 V which can maintain for more than 510 4 cycles. Current-voltage characteristics reveal that Poole-Frenkel tunneling is responsible for electron transport in the Ge-doped HfO x film.

In this paper, a protective coating scheme was applied for the corrosion protection of AZ91D magnesium alloy. Electroless Ni coating (EN coating) as bottom layer, electrodeposited Ni coating (ENN coating), and silane-based coating (ENS coating) as top layer, respectively, were successfully prepared on AZ91D magnesium alloy by combination techniques. Scanning electron microscopy and X-ray diffraction were employed to investigate the surface and phase structure of coatings, respectively. The electrochemical corrosion behaviors of coatings in neutral 3.5 wt% NaCl solution were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The corrosion testing showed that the three kinds of coatings all could provide corrosion protection for AZ91D magnesium alloy to a certain extent, and the corrosion resistance of ENN and ENS was superior to EN. In order to further study the corrosion protection properties of ENN and ENS, a comparative investigation on the evolution of EIS of ENN and ENS was carried out by dint of immersion test in neutral 3.5 wt% NaCl solution. The results indicated that, compared with ENN, the ENS could provide longer corrosion protection for AZ91D magnesium alloy. It is significant to determine the barrier effect of each coating, which could provide reference for industry applications.