Yubing Qiu

Effects of direct current electric field on corrosion behaviour of copper, Cl− ion migration behaviour and dendrites growth under thin electrolyte layer

Abstract Effect of direct current electric field (DCEF) on corrosion behaviour of copper printed circuit board (PCB-Cu), Cl− ion migration behaviour, dendrites growth under thin electrolyte layer was investigated using potentiodynamic polarization and scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS). Results indicate that DCEF decreases the corrosion of PCB-Cu; Cl− ions directionally migrate from the negative pole to the positive pole, and enrich on the surface of the positive pole, which causes serious localized corrosion; dendrites grow on the surface of the negative pole, and the rate and scale of dendrite growth become faster and greater with the increase of external voltage and exposure time, respectively.

Comparison of polynomial fitting and wavelet transform to remove drift in electrochemical noise analysis

Abstract Polynomial fitting and wavelet transform, which could be used to remove trends of electrochemical noise (EN), have been compared in this paper. The typical pitting EN records were chosen to study the effects of these two methods on statistical parameters, power spectral density (PSD), whole energy distribution plot (WEDP) and relative energy distribution plot (EDP), while the indication of selecting the appropriate method was put forward. The results show that for the calculation of the statistical parameters, the polynomial with m<5 and wavelet removal methods all could be selected. Power spectral density plots and WEDPs indicate that the higher order polynomial and wavelet removal methods would reduce the low frequency signals more heavily, so lower order (m=1–3) polynomial is recommended. The appearance of plateau in low frequency part of PSD plots could be regarded as the indication of the best selection of m. Combined EDPs with the analysis of the EN time records, the best m could also be selected, and its value might be just as the same as that obtained from PSD results. In general, the polynomial detrending is a more suitable and flexible trend removal method.

Study of inhibition performance and adsorption behaviour of lauric acid on N80 steel in acidic and near neutral environments

Abstract Inhibition performance and adsorption behaviour of lauric acid in acidic and near neutral environments were investigated by electrochemical and surface analysis methods. The results showed that the inhibition ability and the minimum effective inhibitor concentration are both pH dependent. The former decreased and the latter increased with pH value. The adsorption of the inhibitor was the predominant mechanism at lower pH values, with the formation of a protective adsorption film. At higher pH value, the inhibitor cannot prevent the corrosion process effectively and hence the adsorption of the inhibitor and formation of FeCO3 like corrosion product coexisted. The difference of inhibition performance can be ascribed to the different adsorption state of the inhibitor on metal surface at different pH value resulting in a different interaction with the metal surface, which was validated by vibrational spectroscopy (attenuated total reflection Fourier transform infrared spectroscopy).

Inhibition mechanism of sodium laurate to underdeposit corrosion of carbon steels in NaCl solutions

Abstract In a self-designed occluded corrosion cavity (OCC) simulated cell, the inhibition mechanism of sodium laurate (C12H23O2Na) to the underdeposit corrosion of the N80 steel in a neutral 0·2 mol L–1 NaCl solution was studied by electrochemical methods, including measurements of polarisation curves, coupling currents, polarisation resistances, electrochemical impedance spectra (EIS) and ion selectivity of the scale film. The results show that C12H23O2– could form a monomolecular adsorption film on the N80 steel surface in the studied solution, whose adsorption behaviour would follow Flory–Huggins isotherm model, and inhibit both anodic and cathodic processes. C12H23O2– displays good inhibition performance to the underdeposit corrosion of the N80 steel in the studied system, which could be mainly attributed to the inhibition to the electrode processes of the bulk cathode and occluded anode, the increase in the resistance of the corrosion deposit layer and the prevention to the autocatalysing acidification effect in OCC. The last two factors might be related to the conversion of the deposit layer from anion selectivity to cation selectivity and the formation of a hydrophobic layer on the wall of the micropores in the deposit layer by adsorption of C12H23O2–.

Synergistic Inhibition Effect Between Capsella bursa-pastoris Extracts and Iodide Ions for Q235 Mild Steel in 1 M HCl Solution

The inhibition effect of Capsella bursa-pastoris extracts (CBE) and its synergistic effect with KI (CBEK) for Q235 mild steel in 1 M HCl solution were studied by electrochemical measurements. Both CBE and CBEK can serve as eco-friendly, mixed-type inhibitors, and the inhibition efficiency increases with the concentration and temperature. The synergistic parameter (S I ) indicates a cooperative mechanism between the iodide anions and CBE molecules at lower temperature. The associated thermodynamic and kinetic data suggest the presence of CBEK on metal surface mainly through chemisorption at higher temperature. The adsorption processes follow Langmuir isotherm.

Inhibition Effect Of Dodecylamine On Carbon Steel Corrosion In Hydrochloric Acid Solution

Dodecylamine spontaneously adsorbs on carbon steel via its polar group (-NH2) in hydrochloric acid solution. Furthermore, it forms a monolayer film on carbon steel surface. The inhibition mechanism of dodecylamine for carbon steel is geometric blocking effect. The adsorption of dodecylamine on carbon steel surface follows Arrhenius equation. The adsorption slightly increases activated energy, but greatly reduces pre-exponential factor value. Atomic force microscopy force curves indicate that at the area without adsorbed dodecylamine, no obvious adhere force occurs. At the area with adsorbed dodecylamine, however, an average 1.3 nN adhere force is observed.

Quantifying the Crack Tip Oxidation Kinetics Parameters and Their Contribution to Stress Corrosion Cracking in High Temperature Water

Stress corrosion cracking is the result of the interaction between crack tip oxidation kinetics and crack tip mechanics. Oxidation kinetic processes for austenitic alloys in high temperate water environments are analyzed, emphasizing the effects of alloy composition and microstructure, temperature, water chemistry, etc. The crack chemistry is investigated with introducing the effect of aging on reactivity of crack sides and the throwing power of bulk water chemistry. Oxidation rate constants under various conditions are calculated based on quasi-solid state oxidation mechanism, which are incorporated in the theoretical growth rate equation to quantify the effects of several key parameters on stress corrosion cracking growth rates of austenitic alloys in high temperature water environments, especially the effect of environmental parameters on stress corrosion cracking of Ni-base alloys in simulated PWR environments and stainless steels in simulated boiling water environments.Copyright