Applied Mechanics and Materials Vols. 457-458

Abstract: Temperature programed desorption experiments were carried out for analyzing the TPD spectra of NH₃ desorbed by CaO at different temperature ramp, pressure, and different ratio of CaO to CaSO₄. Moreover, factors affecting on the adsorption process were analyzed. Based on the activation energy of He, NH₃ desorbed at the CaO surface was estimated by experimental spectra and the TPD model.

Abstract: The study with Li₂CO₃ and Mn₃O₄ through the solid state reaction makes cathode material for lithium battery spinel - LiMn₂O₄. According to past literature, under the solid-state reaction. The experiment carries out sintering at temperature of 850°C.. Cathode materials under these sintering temperatures are made to fabricate battery. For Ni doped LiMn₂O₄, the capacitance decreasing speed is slow and stable; after 15 times charging-discharging cycles, the attrition rates were 3.05 % or less. The result of experiment demonstrates that the best sintering temperature is at 850°C. Under the condition of 850°C, various contents for extra amount of lithium (1.02 mole-1.1 mole) are fabricated and range of working voltage is released. It is found a further increase of initial capacity to 140.51 mAh/g. LiMn₂O₄ further extends circulation and usage.

Abstract: In order to extend light response of TiO₂ into the visible region and enhance its photocatalytic activity, V and W surface codoped nanocrytalline TiO₂ film was synthesized by the sol-gel method. Tetrabutyl titanate (Ti (OC₄H₉)₄) was chosen as the precursor, and ammonium metavanadate or ammonium tungstate was chosen as vanadium or tungsten source. The high-resolution field emission scanning electron microscopy (FE-SEM) results revealed that the film was composed of uniform round-like nanoparticles with size smaller than 6 nm. The photocatalytic activities of TiO₂ films were investigated by degradation of organic dyes in aqueous solutions. V and W codoped TiO₂ film exhibited excellent photocatalytic activity compared to undoped TiO₂ film or single doped TiO₂ film. The improvement mechanism by V and W codoping was also discussed. Keywords: Nanocrystalline TiO₂; Composte films; Photocatalytic activity

Abstract: A field experiment was conducted at the vegetable production base of Lixiang town in Shenyang city, Liaoning province to study the effects of dicyandiamide (DCD) application on the accumulation and leaching risk of soil nitrate. The results showed that applying DCD significantly decreased the amount of soil NO₃^--N in the 0-10cm and 10-20cm soil layers compared to without DCD addition (P < 0.01). However, the difference was not significant in the 20-40cm (P > 0.05). These results indicated that the application of DCD reduced the leaching risk of soil nitrate from topsoil to subsoil. At the 28d of fertilizer application, the amount of soil NO₃^--N was higher in the NP+M, NP+M+2%DCD and NP+M+5%DCD treatments than in the M, M+2%DCD and M+5%DCD treatments, suggesting that the combined application of chemical fertilizer and organic manure weakened inhibiting effect of DCD on the amount of soil NO₃^--N.

Abstract: Zinc oxide/poly (butylene succinate) composite (ZnO/PBS) were performed by aging test of 1008h. The chemical structure and crystallinity of the materials were characterized by fourier transform infrared spectroscopy and X-ray diffraction, and the aging properties of composite were studied by mechanical properties. The results showed that: the scale of characteristic functional groups had some change. And any of the reciprocal actions or effects, that can occur in composite molecule. The crystallinity of composite had reduced from 26.13% to 15.56% after aging. Mechanical properties of materials reduced gradually in aging, and reduced extent of ZnO/PBS composite was less than that of PBS.

Abstract: Catalytic hydrolysis decomposition of dichlorodifluoromethane (CCl₂F₂) in the presence of water vapor and oxygen was studied over solid base Na₂O/ZrO₂ using a fixed-bed reactor. The CCl₂F₂ adsorption was multilayer chemical adsorption and its process was corresponding with Freundlich model. Its adsorption heat was from 43.74 to 76.31 KJ.mol^-1, and the CCl₂F₂ adsorption over solid base Na₂O/ZrO₂ was exothermic and chemical.

Abstract: In this paper, suspension polymerization is used for the preparation of PMMA microspheres, PMMA cross-linking DVB microspheres, PMMA-co-St composite microspheres and PMMA-St-SiO₂ composite microspheres, and apply IR spectroscopy, scanning electron microscopy, compressive strength, density, thermal analysis to the prepared polymer microspheres. The purpose of our work is to find the feasibility method of synthesis process for PMMA material and composite microspheres, and the prepared theoretical basis of proppant with low density and high strength for oil drilling applications by performance test.

Abstract: This paper discusses the issues of improving the efficiency of cutting tool made of tungsten-free carbides (cermets) by using nanodispersed multi-layered composite coatings formed by use of innovative processes of filtered cathodic vacuum arc deposition (FCVAD). The paper presents the concept of architecture of nanostructured multi-layered composite coatings, methodology for choice of function and rational component parameters of architecture for tools made of cermets. Developed compositions of nanostructured multi-layered composite coatings contributes to significant improvement of properties of cutting tool made of cermets in cutting constructional steel and expansion of their application area for machining of heat-resistant alloys.

Abstract: Hot-working tools are frequently exposed to high cyclic temperature and mechanical loads, usually resulting in thermal fatigue cracking, which is observed as a network of fine cracks on the surface. The crack network degrades the performance of the tool and even invalidates it. Deep rolling is a surface strengthening treatment generally applied to improve the fatigue performance of metal components. But few attentions are paid on its influence on thermal fatigue cracking of the components, considering the relaxation of residual stresses and work hardening, which are deemed to mainly account for the improvement of fatigue performance. In this paper experiments were carried out to investigate the influence of deep rolling on thermal fatigue behavior of hot-work tool steel AISI H13. The experiment results show that deep rolling can improve the thermal fatigue behavior of AISI H13. To explore the mechanism of the effect, the changes of the residual stresses, the microhardness of the samples are also presented.

Abstract: The aim of this study is to investigate the effect of SiC particle pretreatment, aluminum matrix particle size and sintering temperature on relative density, hardness, microstructure and wear resistance to SiC particle einforced aluminum matrix composites. To this end, the amount of 16.7 wt.% SiC with average particle sizes 20μm was used along with pure aluminum of average particle size of 75 μm and 25μm. Powder metallurgy is a method used in the fabrication of this composite in which the powders were mixed using a planetary ball mill. By analyzing SEM micrograph and the Property test, it is concluded that SiC particle pretreatment has significant effect on the morphology of pecimens. pretreatment increase the interface adhesion, improve the wettability. SiC is uniformly distributed in the matrix, with good relation to the substrate, the maximum hardness is 51.1HB, the minimum wear rate is 0.1684%, while the density is 97.3%.For the same SiC content and particle size, the smaller the particle size of aluminum matrix is, the higher wear resistance of composite materials is on condition that others are same, the higher sintering temperature and the higher the wearability of composites, the wear resistance of the composite material is significantly improved after SiC pre-processing.The relative density increases with increasing aluminum matrix particle sizes under the same pressure and the holding time. The actual density of all samples reached the theoretical density over 96%, to a maximum of 98.9%.