Advanced Materials Research Vols. 631-632

Abstract: FeNi self-fluxing alloy powders and CeO₂ were flame spray welded onto carbon steel, bonding strength investigations of the coating/substrate systems were conducted. The microstructure of the coatings was analysed by a field emission gun scanning electron microscope(FEGSEM), with attached energy dispersive spectroscopy(EDS). The result showed that with the addition of CeO₂, the microstructure of the coatings are refined compared with that without CeO₂. The mechanism of the microstructural refinement by the addition of CeO₂ is dicussed in this paper.

Abstract: The flammability characteristics and thermal stability were studied based on LOI, TG analysis and SEM tests. The results revealed that the additive flame retardant enhanced the flame retardancy of PA. The TG analysis showed that the thermal stability of flame-retardant PA fibers was better than PA fibers, because flame-retardant PA fibers got higher residue content and thermal degradation activation energy. The SEM images indicated the flame retardant residues were infusible, which can impede the molten dropping of PA fibers during combustion.

Abstract: In this paper, the lightweight hybrid materials cab BIW of a commercial vehicle is investigated for material selection. In order to improve the dynamic performance and reduce total mass, the lightweight materials are employed in the BIW. Nine groups of sensitive components are selected to apply the lightweight materials. The design problem is formulated as a multi-objective nonlinear programming problem and the modified non-dominated sorting genetic algorithm (NSGA-II) is used to solve the problem. The surrogate model based on radial basis function (RBF) is adopted in the optimization. The research results show that the usage of steel-aluminum hybrid materials can reduce the total mass and increase the first torsion modal frequency of the cab BIW.

Abstract: We describe approaches using modified carbon aerogels for increasing the weight loading of LiBH4. Large pore volume carbon aerogels were prepared with a sol-gel method and a polymethyl methacrylate (PMMA) microsphere template. Compared to those without using templates, the pore volume has been up to 3.8 times with a PMMA template. After incorporation into carbon aerogels, the weight loading of LiBH4 has reached 80%. Nitrogen absorption/desorption measurements show that more than 95% free space of carbon aerogels has been incorporated with LiBH4. Rama spectra suggest that there is no PMMA or chemical reaction during the synthesis of LiBH4/carbon aerogel composites.

Abstract: Laponite cross-linked poly(vinyl pyrrolidone) (PVP) hydrogels were fabricated by in situ polymerization of vinyl pyrrolidone (NVP). Macroporous PVP/Laponite nanocomposite hydrogels were obtained by freeze drying of hydrogels, which exhibited faster adsorption kinetics than ambient-dried ones. We also investigated the influence of laponite content, initial ion concentration and pH of the solution on the adsorption capacity of PVP/Laponite hydrogels. Moreover, the PVP/Lapnoite hydrogels can further be fabricated into powder hydrogel samples, which can be used as a potential candidate of adsorbent for removal of heavy metals in water.

Abstract: Bi₂S₃ nanorod, nanobelt and flowerlike patterns were synthesized via a facile hydrothermal approach without using any surfactant and acid. The morphology, structure, phase composition, and photoluminescence properties of the as-prepared Bi₂S₃ products were characterized using various techniques (scanning electron microscopy, X-ray diffraction, and photoluminescence spectroscopy). The experimental results showed that the preheating process had a great effort on the morphology of the product.

Abstract: Full dense silicon carbonitride (SiCN) ceramics have been prepared successfully by thermally induced ceramisation of polysilazane precursor at 1000°C, and subsequently annealing at 1200°C. The density and the hardness of the obtained ceramics were about 2.61g/cm³ and 13GPa at the pyrolysis temperature of 1000°C, respectively. The density and hardness have a slight change with the increasing annealing temperature. This meas that the ceramics pyrolyzed at 1000°C were stable.

Abstract: In this work, MoS₂ microsphere was synthesized by hydrothermal reaction, in which thiourea (CS(NH₂)₂) was used as S-source and reducing agent, ammonium heptamolybdate ((NH₄)₆Mo₇O₂₄.4H₂O) was used as Mo-source. The influence of temperature, as well as different dispersing agents, on the reaction product’s morphology, structure and phase composition was discussed. X-ray diffraction results show that all the as-synthesized products are the hexagonal 2H-MoS2 without impurity. SEM images of the as-prepared MoS2 samples without adding any dispersing agent present spherical morphology with sheet-like structures shaped on the surface. A possible formation mechanism of the MoS2 microsphere is that of self-assembly growth process; In addition, for the samples adding surfactant CTAB, SDBS or PVP in the reactants, the MoS2 is confined to layered structure. Compared with SDBS and PVP, CTAB has the best dispersion effect which ensure the as-synthesized microsphere with about 300nm average diameter, and the influence mechanism of which can be deduced as electrostatic interaction and stereo-hindrance effect.

Abstract: In this paper, double deformation test was conducted in a MMS-300 thermomechanical simulator. Austenite static recrystallization kinetics of ultra-high strength dual phase steel was investigated. The results have shown that the softening fractions increase with holding time as a whole. Under deformation temperatures of 950°C, 1000°C and 1050°C, the softening fractions increase with the increase of the deformation temperature. And the softening curve appears relatively flat under deformation temperatures of 950°C. The austenite no-recrystallization temperature (Tnr) of ultra-high strength dual phase steel was between 900°C and 950°C. Double deformation test conditions which promoted Nb(CN) precipitation resulted in a decrease of a austenite recrystallization. Strain induced precipitation of Nb (CN) was the main reason why the softening curve appeared a plateau.

Abstract: A series of spongy foams based on polyurethane (PU) modified by polyisobutylene (PIB) were prepared. The spongy foams with different PIB content were investigated. The results showed that initial adhesion increased with the increment of PIB content, and gained the highest value when the content reached to 30%; FTIR suggested the formation of PU foam modified by PIB; the density also increased with the increasing content of PIB.