Advanced Materials Research Vols. 152-153

Abstract: To find transient braking factor changing model affected by its three main operation factors. A type of drum brake of passenger car was taken as the testing object, a series of practical tests were conducted in brake dynamometers with combination of orthogonal and recursive methods, a formula described transient friction coefficient of drum brake was deduced from test data on the basis of three main factors which are pressure, speed and temperature, which can reflect the drum brake’s performance changing condition influenced by three main factors.

Abstract: Specific to the improvement in the present research of mechanical response under cyclic loading, this paper, taking the calcareous middle- coarse sandstone as the research subject and the RMT-150C experimental system in which data is recoded by ms magnitude as the platform, develops several related models concerning the unloading rate of triangle waves. The unloading process is divided into lag time segment and non-lag time segment, with criterions and related parameters provided as well. The term apparent elastic modulus is defined. The test data analysis shows that there exist a linear relationship between the apparent modulus and instant vertical force before load damage in non-lag time segment. On the preceding basis, a rate-dependent model of triangular wave un-installation section in non-lag time segment is established. Due to the inability of the loading equipment to accurately input the triangle wave, the average loading rate is amended and a constant term is added into it. The model is proved to be reliable, as the predicted value of the deformation rate and the stress strain curve coincides with measured value. At the same time, the impact of the lag time is pointed out quantitatively and a predication model of lag time segment is set up.

Abstract: The paper presents a numerical investigation of mixed-mode crack induced failure of concrete beam strengthened with steel plate. Both the cracking of the concrete and concrete-steel interfacial debonding can be observed. There is a shear stress concentration at the pre-existing crack or debonding tips, which is the root cause of the debonding. The results indicate that debonding only initiates and propagates along the left interface to the steel plate because that the normal stress along the left interface is tensile which make considerable contribution to the debonding and the normal stress along the right interface is compressive.

Abstract: Based on the research of the tribological properties of the Ni60A/MoS2 composite coating, this paper has studied and discussed the self-lubricating effect and mechanism of the MoS2 film in the Ni60A /MoS2 composite coating. Research shows that when self-lubricate coating rub, MoS2 solid lubricant can be precipitated, forming lubricating film on the friction surface through dragging. The Solid lubricate film of MoS2 is an important factor that lead the friction coefficient of Ni60A/MoS2 composite lubricate coating decrease. Meanwhile we analyze the formation phenomenon and friction and wear properties of self-lubricate coating, which show forming mechanism of the lubricating film contain four stages, that is, the friction beginning stage, MoS2 precipitating stage, MoS2 covering stage and MoS2 forming stage.

Abstract: Numerical Simulation of the Reflective Crack Propagation Path for Open-graded Large Stone Asphalt Mixes

Abstract: Thermal decomposition kinetic reaction parameters of KZn2(PO4)(HPO4) was investigated by non-isothermal measurement used in a multivariate non-linear regression analysis. The anticorrosive performance of the phosphate extracts in different pH 3.5% NaCl was studied by polarization and open circuit potential measurements. Kinetics analysis shows that the decomposition of KZn2(PO4)(HPO4) acts as a double-step reaction of : a n order autocatalytic reaction (Cn) with n =1.0791, E1 = 365.06 kJ/ mol, A1 =8.69×1022s−1 is followed by a expended Prout-Tompkins reaction (Bna) with n=2.6548, E2 = 390.91 kJ /mol, A2 = 5.37×1024 s−1. In different pH 3.5% NaCl extracts, KZn2(PO4)(HPO4) functions as a cathodic inhibitor on steel and is even superior to other phosphates in efficiency. The inhibiting efficiency of the pigments on steel decrease in the order: KZn2(PO4)(HPO4) > aluminum zinc phosphate > zinc phosphate ≧ aluminum triphosphate

Abstract: The performance of power lithium batteries directly affects the performance of electric vehicles. To ensure the safety of power lithium batteries and improve battery life, this paper uses Ricoh R5408 Series Li-ion battery protection IC to design the high-current protection board for electric vehicle, to achieve the power lithium battery group overcharge protection, over-discharge protection, over current, short circuit protection, temperature protection and charge balance protection, and has run on the pure electric vehicles with good test results.

Abstract: The effects of yttrium on the microstructure and mechanical properties of magnesium alloy AZ81 have been investigated by alloy preparation, microstructure analysis and tensile tests. The results show that proper content of yttrium addition can obviously refine the microstructure of magnesium alloy AZ81, reduce the amount of β-Mg17Al12 phase, lead to the precipitation of Al2Y phase and improve the mechanical properties. After solid solution and aging treatment, the tensile strength and elongation of the alloy increase at first and then decrease with the increase of yttrium content, and reach the maxima at 2%Y. At room temperature, the maxima are 277MPa and 10.9% respectively. At 150 , the maxima are 220MPa and 12.4% respectively.

Abstract: Heterogeneous photocatalytic materials, titania–phosphotungstic acid nanocomposites in the mesopores of SBA-15 (TiO2-H4PW12O40/SBA15) were prepared by sol–gel method. Compositions and structures of the nanocomposites were characterized by X-ray diffraction (XRD), UV-visible absorption spectroscopy and transmission electron microscopy (TEM). Uniform mesoporous SBA15 consisting of long-range channels provides the immobilization of titania-phosphotungstic acid nanocomposites. The photocatalytic activity of the prepared TiO2-H4PW12O40/SBA15 powders was evaluated from an analysis of the photocatalytic degradation of methyl orange. The results indicated that photocatalytic activity increased with the amount of H4PW12O40 from 0% to 10% and decreased when the amount of H4PW12O40 was above 10%. It is due to the synergetic reaction of H4PW12O40 and TiO2. However, much more H4PW12O40 can occupy the active center of TiO2. TiO2 can inhibit the decomposition of H4PW12O40 in the TiO2-H4PW12O40/SBA15 composites. On the other hand, H4PW12O40 repressed the TiO2 particle growth during calcination process. The composite catalyst also had the advantage of easily being recovered and reused.

Abstract: Quantum dots (QDs) are normally based on the semiconductor materials and widely used in biosensing, bioimaging, biolabeling, and biotreatment for their excellent properties. The ecotoxicity research of QDs correspondingly kept in rising in recent years. CdTe and CdTe/ZnS QDs were prepared via an improved process in aqueous phase, morphology of QDs was characterized with transmission electron microscopy, and optical properties were investigated via fluorescence spectrum. Ecotoxicity of CdTe and CdTe/ZnS were assayed by measuring the inhibitory growth of Rhodococcus sp. strain C1 when QDs existed in broth culture, which was screened from sewage, and its morphology was characterized with optical microscope and scanning electron microscope. CdTe QDs showed strong inhibitory effect against growth of Rhodococcus sp. strain C1, and little growth was observed after 72h cultivation. CdTe/ZnS QDs showed prophasic inhibition before 36h, and growth recovery was observed after 48h of cultivation. Enhanced optical properties and decreasing ecotoxicity were validated after ZnS shell formation, these results indicated that CdTe/ZnS QDs with core-shell structure has great potential in bio-applications.