Papers by Author: Hong Da Deng

Abstract: This present work investigated the corrosion behavior of AZ31 magnesium alloy substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane modified with cerium nitrate. The corrosion behavior of the pre-treated substrates in 0.005M sodium chloride solutions was assessed by potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy (EIS). The results showed that the silane pre-treatments improved the corrosion resistance of the AZ31 magnesium alloy substrates in the presence of chloride ions. Especially the addition of cerium nitrate played an important role in reducing the corrosion activity.

Abstract: In this work, the electrochemical transient behaviors of tubular steel API-P110 in buffered acidic NaCl solutions saturated with 50% H₂S and different content of CO₂ mixture gases, were investigated by single potential step chronoamperometry. Analysis of the results shows that fewer reactants take part in the reduction reaction when adding CO₂ content from 17% to 50% in 50% H₂S containing solution. Anions desorption process controls the reactant transferring process in metal-solution interface in the solution containing H₂S and CO₂. When at higher overpotential, anions desorption enhances and hydrogen absorption depresses with the increasing CO₂ content in H₂S/CO₂.

Abstract: Pressure sensitive paint (PSP) has become a useful tool to measure the surface pressure distribution of aerodynamic components replacing conventional pressure taps. For the PSP technique based on the luminescence quenching by oxygen, improvement of its sensitivity is important. In this study, we synthesized palladium octaethylporphyrin (PdOEP) as luminophor and embeded PdOEP in polydimethylsiloxane (PDMS) as polymeric binder to make up of pressure sensitive paints. We used UV/Vis spectrometer and spectrofluorimeter to study the absorption and phosphorescence spectra of PdOEP. In addition, by our self-made experimental setup, the sensitivity of PSPs were examined especially in the range of pressure below 150 Pa. As a result, it is clarified that the PSP using PdOEP as a luminophore and using PDMS as a binder has very high sensitivity to oxygen pressure in low pressure conditions below 150 Pa.

Abstract: In the present work, the resistances to corrosion of heat treated soft magnetic alloy Fe81Cr17Si1.5TiBRe and untreated one have been comparatively studied, which were tested in neutral salt spaying tester, in 50%vol. hydrochloric acid (HCl) at 100 , in humidity thermal oxidation tester, specially in simulating oilfield waters containing sulfide ion (S2-) and without S2-. Heat treatment was carried out at 1150 for 4 hours under the protection of hydrogen gas. The results show that heat-treatment affect the magnitude of grain of Fe-base soft magnetic alloy and distribution of inclusions in grain and in grain boundaries. Heat treatment enhances anti-corrosion properties, i.e. resistance to chlorine ion (Cl-) corrosion of the alloys, resistance to humidity thermal oxidation corrosion, oilfield water corrosion. The electrochemical corrosion mechanisms of the alloy in oilfield waters are not affected by heat treatment. In simulating oilfield water, the passivity property of the alloy is affected by S2- or HCO3-.

Abstract: The atmospheric corrosion has been shown to be an electrochemical process, the atmospheric corrosion behavior of Q235 stell evaluated with ACM (Atmospheric corrosion monitor) electrochemical technique was investigated in the study. The experimental results showed that there existed a close relation between electrochemical data and climatic parameters was confirmed. Taking into consideration accuracy and sensitivity of electrochemical technique, the ISO-standardized time of wetness (TOW) seems to be too conservative. SO2 seems to be more aggressive than chloride on metal corrosion in the early stage of atmospheric corrosion but the complexion reverses in the final stage of atmospheric corrosion. The ratio of corrosion rate from integration of ACM current to corrosion rate from weight loss of test specimens, that is, cell factor is fairly constant at the same test site but varied greatly between test sites. Based on constant cell factors and close relation between electrochemical data and climatic parameters in all test sites, ACM electrochemical technique can evaluate and classify the short-term atmospheric corrosivity as a substitute for gravimetric method, and the verification shows that atmospheric corrosivity classifications according to integration of ACM current and especially to cell factor coincide with the specifications of ISO Standard.