Shuan Liu

Facile Preparation of Water-Dispersible Graphene Sheets Stabilized by Carboxylated Oligoanilines and Their Anticorrosion Coatings

Dispersion of graphene in solvents is of crucial importance toward its practical applications. In this study, using a water-soluble carboxylated aniline trimer derivative (CAT(-)) as a stabilizer, the commercial graphene can be stably dispersed in water at high concentration (>1 mg/mL) via strong π-π interaction that was proved by Raman and UV-vis spectra. Moreover, the CAT(-)-functionalized graphene sheets (G-CAT(-) hybrid) exhibited high conductivity (∼1.5 S/cm), good electroactivity and improved electrochemical stability. The addition of well-dispersed graphene into waterborne epoxy system (G-CAT(-)/epoxy) remarkably improved corrosion protection compared with pure waterborne epoxy coating, based on a series of electrochemical measurements performed under 3.5% NaCl solution. This significantly enhanced anticorrosion performance is mainly due to the improved water barrier properties derived from highly dispersed graphene nanosheets in the epoxy coating.

Anticorrosive oligoaniline-containing electroactive siliceous hybrid materials

In this work, a novel electroactive silsesquioxane precursor, N-(3-triethoxysilylpropylureido) aniline tetramer (TESPAT), was synthesized via one-step coupling reaction between phenyl-capped aniline tetramer (AT) and 3-(triethoxysilyl)propyl isocyanate (TESPIC) under mild conditions. The chemical structure and electroactivity of the resulting silsesquioxane precursor were investigated by FTIR, NMR, UV-vis spectra, and cyclic voltammetry. Subsequently, the sol–gel reactions of TESPAT with triethoxymethylsilane (TEMS) at various compositions were carried out to achieve new electroactive siliceous hybrid materials with good thermal stability. Furthermore, polarization curves and electrochemical impedance spectroscopic (EIS) measurements indicated that the obtained hybrid materials exhibit remarkably enhanced corrosion protection on Q235 electrodes as compared to pure silica coating. The significantly improved anticorrosion performance is attributed to the redox catalytic capabilities of the AT units in the hybrid materials.

Tribological properties of attapulgite/La2O3 nanocomposite as lubricant additive for a steel/steel contact

Attapulgite is a layered silicate with good friction-reduction and self-repairing properties. In order to further improve its tribological properties, the present work mainly focuses on the preparation of attapulgite/La2O3 nanocomposite and study on its tribological behaviors. The tribological properties of mineral lubricating oil (150SN) containing attapulgite/La2O3 nanocomposite were investigated through an Optimal SRV-IV oscillating friction and wear tester. The rubbing surfaces and generated tribofilms were characterized by SEM, EDS, XPS and nanoindentation. Results indicated that the friction-reducing ability and antiwear property of the oil were both remarkably improved by attapulgite/La2O3 nanocomposite. A tribofilm mainly composed of Fe, Fe3C, FeO, Fe2O3, FeOOH, SiO, SiO2 and organic compound was formed on the rubbing surface under the lubrication of oil with attapulgite/La2O3 nanocomposite. The tribofilm possess excellent self-lubricating ability and mechanical properties, which is responsible for the reduction of friction and wear.

Corrosion performance of zinc coated steel in seawater environment

Considering the continuous exploitation of marine resources, it is very important to study the anticorrosion performance and durability of zinc coated streel (ZCS) because its increasing use as reinforcements in seawater. Tafel polarization curves and linear polarization curves combined with electrochemical impedance spectroscopy (EIS) were employed to evaluate the corrosion performance of ZCS at Qingdao test station during long-term immersion in seawater. The results indicated that the corrosion rate of the ZCS increased obviously with immersion time in seawater. The corrosion products that formed on the zinc coated steel were loose and porous, and were mainly composed of Zn5(OH)8Cl2, Zn5(OH)6(CO3)2, and ZnO. Pitting corrosion occurred on the steel surface in neutral seawater, and the rate of ZCS corrosion decreased with increasing pH.

Corrosion Behavior of Pipeline Steel X65 in Oilfield

The inner- and outer- surface corrosion behavior of X65 pipeline steel used in Shengli Chengdao oilfield was studied in this paper. The inner surface corrosion behavior of X65 pipeline steel in oil-water mixtures with different flow rate and oil content was examined by means of mass loss method and electrochemical technique. The corrosion resistance of the outer surface of X65 pipeline steel in soil extracts was also examined by means of polarization curves and electrochemical impedance spectroscopy (EIS). The phase constituents and surface morphology of corrosion products were characterized by using X-ray diffraction techniques (XRD) and scanning electron microscopy (SEM), respectively. The results indicated that the corrosion rate of X65 steel increased with the increasing flow rate of oil-water mixture, which could reach the maximum value when the oil content was 0.5% (mass fraction). The corrosion current density of X65 steel increased with immersion time in soil extracts. A loose corrosion product film formed on the steel surface, which can accelerate the cathodic depolarization reaction.