Advanced Materials Research Vols. 785-786

Abstract: The cyclic oxidation behavior of Co-10Cr-5Si alloys with and without Y in atmosphere at 800 °C was investigated. The addition of 0.3 at.% Y decreased the average parabolic rate constant from 4.45×10^-10 g²cm^-2s^-1 to 3.58×10^-10 g²cm^-2s^-1. The thin scales grown on Co-10Cr-5Si alloys were mainly composed of an outer CoO layer, followed by an inner protective SiO₂ layer. However, the scales can not be observed for Co-10Cr-5Si-0.3Y alloy, probably due to the spallation of the scales during the cooling process. The addition of 0.3 at.% Y improved the cyclic oxidation resistance of the Co-10Cr-5Al alloy.

Abstract: The Sn whisker growth in Cu(top)-Sn(bottom) bilayer system upon room temperature aging was investigated by scanning electron microscope and X-ray diffraction techniques. The experimental observations indicate that the Sn whisker growth on the Cu surface in Cu-Sn bilayer system is different from that on the Sn surface in Sn-Cu bilayer system. When the Sn sublayer thickness is less than 0.5μm, the Sn whisker growth can take place in Cu-Sn system but not in Sn-Cu system. An explanation for Sn whisker growth in Cu-Sn bilayer system is given.

Abstract: In this paper, Zn-Sn target material alloys were prepared in an electric resistance furnace. The effects of cooling condition on casting macro-defect, microstructure and segregation of ingots during solidification have been investigated by SEM and EDX analyses. The results show that the alloys casted in air-cooled and water-cooled steel moulds have not apparent casting macro-defects. The measured Sn concentration of alloys is very close to the nominal composition. The microstructures of Zn-Sn alloys are consisting of Zn-rich primary dendrite phase and divorced eutectic Sn-rich phase. The ingots solidified in water-cooled steel moulds have smaller grains than in air-cooled moulds.

Abstract: Effect of grain size and Cl^- concentration on corrosion behavior of Cu was investigated by using a series of electrochemical analysis in borate buffer solution (pH=8.40).The results indicated that in all cases, the Mott-Schottky plots of the passive films on the surface of Cu were linear with negative slop, and showed behavior of the p-type semiconductor.With the decrease of the grain size and the increase of anode passivation potential, the acceptor density (N_A) of the passivation film on the surface of Cu was reducing. As the concentration of Cl^- in the medium solution was heightening, the acceptor density (N_A) of the passivation film on the surface of Cu was increasing.

Abstract: In this paper, nanoSiO₂ used to be an accelerator of Zinc phosphatization for electrochemical inhomogeneity in the process of phosphate coatings on carbon steel by wire-beam electrode. The open circuit potential of the phosphated samples was analyzed using average method. The result showed the large influence of nanoSiO₂ on the nucleation and growth of the phosphate coatings.

Abstract: Nucleation kinetics of Ni-nanoCr₂O₃ composite coating during early electro-crystallization was investigated. The results showed that, the early electro-crystallization processes of Ni-nanoCr₂O₃ composite coating and pure Ni coating followed a Scharifker-Hill nucleation/growth mechanism. At the low potential, the nucleation process of pure Ni and Ni-Cr₂O₃ composite system may approach to the progressive nucleation model; With the overpotential increasing, the nucleation model of Pure Ni and Ni-Cr₂O₃ composite system converts into the instantaneous nucleation mechanism controlled; at the same overpotential, Cr₂O₃ powder promotes the electro-crystallization nucleation of Ni. But at high negative potential, Cr₂O₃ powder in composite system promotes the electro-crystal nucleation of Ni weakly; the nanoCr₂O₃ powder added reduces the current efficiency in the nucleation process of Ni.

Abstract: In this paper, the semiconducting behavior of non-solid electrochemical state of carbon steel in acid, base and salt solutions was studied by utilizing potential-capacitance and Mott-Schottky analysis. It was pointed out that the capacitance variation of space charge layer of non-solid electrochemical state of carbon steel in different solution was different. The non-solid electrochemical state showed p-type semiconducting behavior in 5 sulfuric acid and 5 % sodium sulfate solution. However, it showed n-type semiconducting behavior in 5 % sodium hydroxide, suggesting that the space charge layer of non-solid electrochemical state of the carbon steel in different electrolytes might be asymmetric.

Abstract: The electrodeposition of Ni-Fe-Cr alloys was investigated in a trivalent chromium electrolyte on the surface of mild steel over a range of current density. Scanning Electron Microscopy (SEM), Tafel plot and Electrochemical Impedance Spectroscopy (EIS) measurements were used to compare plated alloy coatings and heat-treated electrodeposited alloy coatings. The heat-treated alloy coatings showed a relatively large impedance values and corrosion inhibiting efficiency. Moreover, the polarisation resistance, R_p, was obtained by EIS modeling using equivalent circuits.

Abstract: Cu-Ni-W alloy coating was electroplated on the surface of mild steel and the effect of Cl^- concentration on its corrosion behavior was evaluated in this paper. Polarization techniques and electrochemical impedance spectroscopy (EIS) have been used to investigate the corrosion behavior in aqueous solution contain various Cl^-. The results showed that The increased Cl^- is prejudice for the Cu-Ni-W coating from 0.01 to 0.3 mol/L, and the critical value of Cl^- content is 0.3 mol/L, the coating corrosion present better resistance when immerse in the solution with Cl^- content exceeds the critical value or more .

Abstract: Sequential control is to use binary information digital technology of automatic control mode. Realization sequential control most has three kinds representative method: sequence table method, expression method and ladder diagram method. In this paper, we analyzed polymerizer coating technological process and Sequence Control Flow, then make use of CENTUM CS-3000s sequence table to realize the polymerizer coating completely automatic sequential control. The practice proved that it improved polymerizer coating effect, raised the equipment utilization rate and the PVC quality. it had the widespread application promotion value.