Qing Dong Zhong

The Effect of Grain Size and Cl-Concentration on the Passive Behavior of Cu in Borate Buffer Solution

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 (NA) 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 (NA) of the passivation film on the surface of Cu was increasing.

Catalytic Reforming of Model Tar Compounds from Hot Coke Oven Gas over Pd Promoted Ni/Mg(Al)O Catalysts

Pd (0.1-1 wt%) loaded Ni/Mg(Al)O catalysts have been prepared by co-precipitation and impregnation methods, and their catalytic activities were tested in the catalytic reforming of tar components from hot coke oven gas (COG) with lower steam/carbon (S/C) molar ratio. The 0.5%Pd-12%Ni/Mg3(Al)O bimetallic catalyst derived from hydrotalcite showed excellent catalytic activity. The effect of reaction temperature on the catalytic performance was investigated in detail. Toluene could be completely converted into small gas molecules of CH4, CO and CO2 over the catalyst at S/C=0.42 and 600°C under atmospheric pressure.

Improving Performance of BaCo0.7Fe0.2Nb0.1O3-δ Ceramic Membrane by a Surface-Coating Layer for Partial Oxidation of Coke Oven Gas

The BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) membranes combined with Ce0.8Re0.2O2-δ (Re=La, Y) layer on the permeation side were used for hydrogen production by partial oxidation reforming of coke oven gas (COG). The Ce0.8Re0.2O2-δ improved the oxygen permeation flux of the membrane by 11–28% at 750 oC. The high oxygen permeation flux achieved using the Ce0.8Re0.2O2-δ surface-coating layer in this work are quite encouraging with a maximum value reaching 19.7 ml/cm2•min at 900 oC, which will be promising surface modification materials in the catalytic partial oxidation reforming of COG.

The Electrodeposition of Ni-Fe-Cr Alloy Coatings on Mild Steel Surfaces and Evaluation of Corrosion Resistance

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, Rp, was obtained by EIS modeling using equivalent circuits.

Kinetics of Ni-Nano Cr2O3 Composite Coating during Early Electro-Crystallization Processes

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.

Semiconducting Behavior of Non-Solid Electrochemical State of Carbon Steel in Electrolyte Solution

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.

Investigating Electrochemical Inhomogeneity on Phosphating Process of Nano-SiO2 Additive Using Wire-Beam Electrode

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.

The Effect of Cl- Concentration on the Corrosion Behavior of Electroplated Cu-Ni-W Alloy Coating

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 .

Novel Electrochemical Behavior of Organic Polymer Coating in Alkaline Solution

The semiconducting behavior of No.20 carbon steel coated with different polymer coating in 5% sodium hydroxide solution was studied by utilizing potential-capacitance and Mott-Schottky analysis. Results showed that the phenol aldehyde resin and alkyd resin behaved as bipolar film, showed p-type semiconducting behavior at the potential range of -0.3V ~ -0.1V vs. SCE and as an n-type semiconductor at the potential range of 0V ~ 0.4V vs. SCE in 5% sodium hydroxide, whereas for the epoxy resin, it showed as an insulator in 5% sodium hydroxide solution at the same condition.

Electrodeposition and Hardness and Corrosion Resistance Propertie of Ni/Nano-B4C Composite Coatings

Ni–B4C composite coatings on carbon steel substrates with various contents of B4C nano-particulates were prepared by electrodeposition in Ni plating bath containing B4C nano-particulates. Microhardness, Scanning Electron Microscopy (SEM), Tafel polarization and Electrochemical Impedance Spectroscopy (EIS) measurements were used to compare pure nickel coatings and Ni–B4C composite coatings. Pure Ni coating microhardness is lower than that of Ni–B4C coatings and the microhardness of the composite coatings increases with the increase of the content of B4C nano-particulates. The effects of various contents of B4C nano-particulates on the corrosion resistance were investigated and it was found that the best anti–corrosion property of Ni–B4C composite coatings is at 6 g/L B4C in the bath formulation.