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In this paper, polyimide-graphite (PG) composite was prepared and used as a solid lubricant at elevated temperatures. PG composite was characterized by X-ray diffraction, and its thermal stability was evaluated based on thermogravimetric/differential thermal analysis and Fourier transform infrared spectrometry analysis. The results show that in PG composite, there was some interaction between the graphite (GR) and the polyimide (PI) matrix. Consequently, the PG composite exhibited better thermal stability than PI. The friction behavior of the PG composite sliding against steel at elevated temperatures (300–600°C at an interval of 100°C) was evaluated with a ring-on-ring tribometer. It was found that the PG composite exhibited excellent friction-reducing ability and good load-carrying capacity in the temperature range of 300–600°C and applied loads of 300–700 N. Moreover, this excellent lubricating performance of the PG composite might be attributed to its good thermal stability as a result of the interaction between the GR and the PI matrix. Therefore, PG composite could be used as an excellent solid lubricant under the high-temperature conditions.

The effects of pre‐exposure and surface notch on the tensile properties of T91 steel in oxygen saturation lead–bismuth eutectic (LBE) have been investigated by slow strain rate tensile tests at 350°C with a strain rate of 1 × 10−5 s−1, and the reference tests were performed in Ar gas. The pre‐exposure was conducted in liquid LBE at 500°C with an oxygen concentration of 10−8 wt% for 500 h. It is shown that the tensile properties of the nonpre‐exposed specimens whether with or without a notch were not affected by LBE, but obvious liquid metal embrittlement (LME) was observed on the pre‐exposure specimens. After being pre‐exposed, the notched one was more prone to liquid LBE embrittlement compared to the unnotched specimen. Morphology similar to fatigue striations was observed on the fracture surface of the notched specimen with pre‐exposure, which was probably attributed to the rapid growth of the crack. The results revealed that pre‐exposure had a critical effect on LME, and surface notch intensified this phenomenon when pre‐exposure was present. [ABSTRACT FROM AUTHOR]

Corrosion tests of T91 were carried out in the stagnant lead–bismuth eutectic (LBE) containing 10−6, 10−7, and 10−8 wt% oxygen at 500°C for up to 2000 h, respectively. The dependence of corrosion characteristics on oxygen concentrations in LBE was obtained. The results show that the oxide‐scale structure changes from a three‐layer magnetite/spinel/internal oxidation zone (IOZ) scale under the oxygen concentration of 10−6 wt%, to the formation of a two‐layer spinel/IOZ scale under the oxygen concentrations of 10−7 and 10−8 wt%. In addition, with the decrease of the oxygen concentration, the Cr/Fe ratio in the Fe–Cr spinel slightly increases in a linear rule while the thicknesses of the oxide layers gradually decrease. [ABSTRACT FROM AUTHOR]

Nano zero-valent iron (NZVI) particles were prone to forming aggregates owing to their intrinsic magnetism and van der Waals force. In this work, a composite material containing mesoporous silica MCM-41 and NZVI was prepared to avoid the problem of NZVI aggregation. The structures and morphologies of the as-prepared composite were confirmed using X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, N2adsorption–desorption, and X-ray photoelectron spectroscopy techniques. It was found that NZVI particles were well dispersed in the composite, although the size of NZVI particle was larger than that of bare NZVI. Moreover, the composite was used as adsorbent for removing Pb(II) from aqueous solution at room temperature. The effects of contact time, initial solution pH, and adsorbent dosage on the removal efficiency of Pb(II) were studied using batch adsorption experiments. The results indicated the composite exhibited enhanced adsorption properties, with the maximum adsorption capacity of 416.17 mg/g for Pb(II) removal from aqueous solution. In addition, the adsorption isotherms and adsorption kinetics were also investigated systematically, it was found that the isothermal data were well fitted to Langmuir model, and the kinetic data were well suitable to pseudo-second-order kinetics model. [ABSTRACT FROM PUBLISHER]

In this study, a series of chitosan-stabilized nano zero-valent iron (CNZVI) composites with different amounts of chitosan were prepared and characterized by Fourier transform infrared spectra, X-ray diffraction, and transmission electron microscopy. The adsorption capacity of these composites was evaluated by the removal experiment of cadmium ion (Cd2+) from aqueous solution. These results showed that the as-prepared CNZVI8composite with loose aggregate structure has the maximum adsorption capacity for Cd2+. Furthermore, batch adsorption experiments of Cd2+on CNZVI8composite were performed under various conditions, such as contact time, adsorbent dosage, initial Cd2+concentration, and the initial pH of solution. The data revealed that the maximum adsorption capacity of CNZVI8is 124.74 mg/g. The removal efficiency of Cd2+increased with the increase in solution pH value, and reaches 99.9% at pH 6. In addition, the adsorption isotherm and the adsorption kinetics of Cd2+on CNZVI8were also investigated, suggesting that the isothermal data were well fitted to the Langmuir model and the kinetic data were well suitable to the pseudo-second-order kinetic model. [ABSTRACT FROM PUBLISHER]