Applied Mechanics and Materials Vols. 716-717

Abstract: In this paper, Fe₃O₄ magnetite nanoparticles decorated multi-walled carbon nanotubes (MWCNTs-Fe₃O₄) nanocomposite was successfully prepared. Firstly, carboxyl-functionalized MWCNTs were obtained after acid oxidization. Then, Fe₃O₄ nanoparticles were attached onto the surface of MWCNTs through chemical reaction between hydroxyl groups on the surface of Fe₃O₄ nanoparticles and carboxyl groups on the surface of MWCNTs.

Abstract: In this study, oligomer Joncryl^TM ADR was used to extend the chains and improve the mechanical properties. The chain extender multifunction epoxide was used with concentrations of 0.5 and 0.9 wt %. Pure and modified PLAs were characterized using DSC, MFI and FT-IR. The DSC results showed that Tg shifted to the high temperature and T_m increased slightly after chain extending. The MFI of the blends decreased with increasing the content of the CE which means the increase of molecular weight. The coupling between epoxy groups of CE and end groups of PLA was confirmed by FTIR tests. This coupling led to significant improvement in tensile strength and modulus.

Abstract: The effects of tungsten (W) addition on the microstructure, impact toughness and tensile properties of a microalloyed cast steel were systematically investigated. The results indicate that W alloying in microalloyed cast steel plays a positive role in inhibiting dendrite during casting process, and the yield strength, ultimate tensile strength and fracture strain can be simultaneously improved after W addition. Both microalloyed cast steels with and without W additions show very low impact energies, indicating W addition has no significant effect on the impact toughness. The present work provides a possibility to develop new W-containing microalloyed steels with improved mechanical properties.

Abstract: Effect of Cr addition on microstructure and mechanical property of Cu-17Ni-3Al-1.2Fe alloy were investigated by means of tensile testing, optical microscope (OM), scanning electronic microscope (SEM) and transmission electronic microscope (TEM). The results showed that the morphology and type of second phases which exist among dendrites change significantly with the addition of 0.85 wt % Cr. A lot of rod-like and multi-branched Cr-rich phases can be observed while the formation of Ni₃Al is suppressed. However, Cr addition does not change the type of particle-like Ni₃Al which evenly distributes in the matrix. With the addition of Cr in Cu-17Ni-3Al-1.2Fe alloy, the tensile strength, yield strength and Brinell hardness increase, especially the yield strength with the increase of 31%, however, the elongation decreases slightly.

Abstract: The concept of homogeneity of materials and the aim for the evaluation of homogeneity were introduced. It was discussed in detail for the application of one-way ANOVA into the evaluation of homogeneity of materials and the role which a statistical quantity plays in the different range. It can be illustrated that a small F value is necessarily not considered as a criterion of qualified homogeneity. It was also pointed out that the inhomogeneity with sample may cause a small F value. Based on the theoretical explanation, an equation was given for the threshold value of small F. A calculation of the threshold value of small F occurring in the common experiments was made using the routines of numerical integration. An investigation into the origin of small F value was carried out. Moreover, the regional inhomogeneity and its criteria were also shown.

Abstract: Li and Al codoped ZnO (LAZO) thin films have been prepared by sol-gel method. There are two emission bands were observed in the spectra of pure ZnO thin films. One band possessed a sharp peak at round 380 nm locating in the UV range; the other band consists of green luminescence. Yellowish-white emission were observed from the LAZO films, which can be fitted into three bands: a strong yellow emission, a moderate green emission and a weak violet emission centered at 598, 538, and 430 nm, respectively. The luminescence color was seen to be yellowish white due to the recombination for the dominant green and yellow emission.

Abstract: To solve the confusing problem of different grades of slurry in the grades pipeline, this paper presents a new technology for slurry sizing dehydration. The method realizes the grading treatment by making full use of dehydrating station agitation tank and thickener buffer storage capacity. Research has shown that the method can effectively solve the grading dehydration process after the arrival terminal dehydration station in different grade slurry, and ensure the multi-grade mineral classification sequence transportation process completed successfully.

Abstract: Natural rubber (NR)/epoxidized natural rubber (ENR)/carbon black (CB), natural rubber/butadiene rubber (BR)/carbon black and natural rubber/isobutylene-isoprene rubber (IIR)/carbon black compounds were prepared by mechanical mixing method. The mechanical properties, dynamic mechanical properties for the compounds were investigated respectively. The temperature range of tanδ>0.3 of NR/ENR40/CB compound was wider and shifted to high temperature than NR/CB compound. Comprehensive analysis indicated that NR/BR/CB and NR/IIR/CB compounds had no better damping performance than NR/CB compounds, while NR/ENR/CB compound had better damping performance.

Abstract: An investigation of low Si spring steels (50CrVA) subjected to quenching-isothermal-quenching-tempering (Q-I-Q-T) process is presented. The results indicated that Q-I-Q-T process lead to the excellent mechanical properties compare to those treated by traditional heat-treatment, quenching and tempering, owing to the multiphase structure. The Q-I-Q-T treated microstructure consists of martensite, retained austensite, bainite and fine distributed carbides.

Abstract: The competitive adsorption isotherm of etodolac enantiomers on a cellulose carbamates-based chiral stationary phase (Chiralcel OD) at 25°C was determined in this study by the inverse method (IM). An equilibrium dispersive (ED) model combined with bi-Langmuir adsorption model was used in predicting the elution profiles. The adsorption isotherm model with 5 parameters was determined by fitting the two overloaded band profiles. The non-dominated sorting genetic algorithm (NSGA-II) and Levenberg-Marquardt algorithm (LMA) were crucial tools and utilities in this process. Suitable model parameters have been obtained and the experimental results were in good agreement with the model predictions.