Abstract: It is great significance to study self-healing aluminum alloy materials for spacecraft the structure protection from high energy space weapon attack and debris impact in future. In this paper, Using aluminum alloy (6063) as matrix material with low melting point alloy (Sn60Pb40, the melting point of 183°C) as repairing materials, the self-healing Aluminum Alloy material was designed and manufactured by the smelting and casting method. The crack damage repair performance of the self-healing Al alloy was researched through the experiment. The results show that the self-healing aluminum alloy has certain self-healing ability without help, when the temperature reaches the melting point temperature of Sn60Pb40. The repair time is about 20min, the crack filling rate can reach 84%. The research conclusion can provide a reference for the development of metal self-healing material technology.
Abstract: In this study, cold spray technique was used as a solid-state additive manufacturing route to deposit a 5 mm thick SiC /Al metal matrix composite. Microstructure and tensile properties were analyzed via different heat treatment conditions (200 oC, 300 oC, 400 oC and 500 oC). Microstructure evolutions were characterized via scanning electron microscopy, X-ray diffraction (XRD) and energy-disperse X-ray spectroscopy (EDS), whilst mechanical properties were investigated via micro-tensile and hardness tests. It was established that the as-sprayed deposit fractured in a brittle manner and had appreciable tensile strength (85 MPa) mainly associated with intensive work hardening effect. At heat treatment conditions, tensile strength (104 MPa) and plasticity (1.5 %-5.2 %) were enhanced due to coarsening of pure Al splat through recrystallization-recovery-grain growth mechanisms. The splat size which controls strength changes from 30.9 ± 2.6 μm to 40.9 ± 4.8 μm, an appreciation of 32 % as heat treatment temperature increased. The main fracture mode at the heat treatment state was a ductile fracture. For plastically deformed splats, the flattening ratios (FR) revealed the top (1.5), middle (1.9) and near interfacial regions (2.2) due to peening effect of SiC particles. The Young moduli were in agreement with the experimental results.
Abstract: Iron oxides-doped carbon microspheres composites were synthesized by one-pot hydrothermal methods using Fe (NO3)3·9H2O as the iron source and glucose as the carbon source. The morphology, particle size and crystal structure can be controlled flexibly by altering the concentration of ferric salts and glucose. The SEM and XRD were used to characterize the physicochemical properties of materials. The SEM images indicated that the composites were microspheres, and as the salts concentration increase, adhesion occurred between microspheres. The XRD results showed that the composites were composed of Fe3O4 and amorphous carbon. The materials were applied to photocatalytic degradation of dye wastewater and possessed high performance.
Abstract: In this study, the effects of Al2O3 additives on the anticorrosion and tribological properties of Mn3(PO4)2-coated carbon steel were investigated. The microstructure and morphology of the coatings were studied by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The Vickers micro-hardness and wear resistance of the produced composite coatings were evaluated and compared with those of the non-composited Mn3(PO4)2 coating. The electrochemical corrosion behaviors of the prepared coatings were investigated in a 3.5 wt.% NaCl solution by a potentiostat–galvanostat device to determine the effects of Al2O3 on the formation of Mn3(PO4)2 coatings on steel. Mn3(PO4)2 composite conversion coatings were successfully created by chemical treatment, with the main component of hureaulite [(Mn,Fe)5H2(PO4)4∙4H2O]. The micro-hardness, wear resistance, corrosion performance, and passivation behaviors of the coatings were improved by adding Al2O3 particles. The optimum concentration of Al2O3 particles in the Mn3(PO4)2 coating to attain the best microstructure, wear resistance properties, and corrosion resistance was 10 g/L.
Abstract: In this study the Ni-Al2O3-Zn coating was prepared on the surface of Q345R steel by cold spraying technique. The gas temperature, the content of Zn and the thickness of the coating were changed during spraying. The relationship between coating bond strength and three variables were studied. The results show that the bonding strength is the highest when the temperature is 400°C, the Zn content is 20% and the coating thickness is 0.5mm. It is found that the addition of Zn can significantly improve the bonding strength of the coating.
Abstract: The absorption rate of fabric-foam-fabric plied materials for making intimate apparel was measured in this study. The fabric-foam-fabric plied materials were prepared by plying polyurethane foams (non-laminated and laminated) with different fabrics. The plied material is intended to be used in close-to-skin garment. Thus, the water absorption behaviour of the material would affect its comfort property. Therefore, we reported the absorption rate values of different plied samples and the results were discussed properly.
Abstract: Based on technical difficulties of graphite water-lubricated thrust bearing such as preparation and properties detection, this paper investigated graphite bearing systematically from preparation and property testing, three different types of graphite (#1, #2 and #3) were carried out. The result indicated the tribological properties are poor if the graphitization of graphite is too high or low. The pads of water-lubricated thrust bearing are manufactured by the three kinds of graphite, and the start-stop test were carried out on a test platform for half-size bearing of nuclear primary pump. The result of start-stop test were indicated the graphitization have a visible influence on the wear loss mass of graphite pad.
Abstract: Chromatographic stationary phases with specific capturing phosphoproteins is widely used in biological sample pretreatment. However, when captured protein is released, it is required to change the pH of the mobile phase or to use an eluent. Usually, the mobile phase or eluent are salt solutions with high concentration and extreme pH or toxic organic reagents. In this situation, these reagents will destroy the activity and structure of phosphorylated proteins. In addition, the mobile phase after switching the column takes longer time to restore the balance, reducing the experimental efficiency. In order to solve the these problems, we introduce temperature-reponsive materials into the chromatographic stationary phase to achieve the capture and release of phosphorylated proteins by changing the temperature only, in which we use water as the mobile phase. This approach overcomes the drawbacks of traditional methods, and makes the separation process safe and simple. Based on the surface initiated Reversible Addition Fragmentation Chain Transfer Polymerization (SI-RAFT) method, silica@pNIPAAm-nanoTiO2, a kind of Metal Oxide Affinity Chromatography, was synthesized by the rapid introduction of functional groups. The synthesis of silica@pNIPAAm-nanoTiO2 was confirmed by infrared and X-ray photoelectron spectroscopy. The grafting rate and the lowest critical temperature were measured by TG and DSC. The results showed that the material had qualified temperature-sensitive properties. The grafting conformation and mobile phase pH of the material were optimized before testing the properties and found that when the material grafting ratio was 10% -15%, the graft density was 30%, and the mobile phase pH was 6, it had the best separate effect. Finally, the material successfully achieved the capture and release of adenosine triphosphate and casein phosphopeptides.
Abstract: Preparation of carbon supported nanometal catalysts were realized through the carbonization of metal precursor doped carboxymethyl cellulose under nitrogen condition. This carbon supported nanometal catalyst exhibited good activity in the reductive amination of amine. The results suggested a promising one-pot route based on economical and sustainable biomass towards the development of value carbon materials as effective catalyst for C-N bond synthesis reaction.
Abstract: Poly-γ-glutamic acid (γ-PGA) produced by Bacillus pumilus C2 was employed to remove heavy metals from sewage of magnesium - based exhaust gas cleaning system (Mg-EGCS). The components of heavy metals in the sewage were detailed analyzed. On the base of the analytical results, the effects of addition amount of γ-PGA, adsorption time, temperature and NaCl concentration on the removal efficiency of typical heavy metals were further investigated. The optimal removal rates of heavy metals were obtained at the γ-PGA dosage of 9 g/L and adsorption duration of 30 min. The γ-PGA had excellent tolerance for high temperatures up to 80°C and exhibited steady heavy metal removal efficiency in NaCl concentrations of 0 – 24%. Under the optimal conditions, the removal rates of Zn, Cr, V, Cd, Pb and Ni by γ-PGA in a real sewage of Mg-EGCS achieved 53.6%, 100%, 49.2%, 72.7%, 33.7% and 39.9% respectively.