Advanced Materials Research Vol. 773

Abstract: Spherical silica particles, with mean sizes about 1.2 μm, were prepared through TEOS sol-gel process catalyzed by ammonia. The silica particles have a smooth surface and a small specific surface area, 3.4 m²/g. The sol-gel process was monitored by React IR^TM using an in-situ technique. Based on the measurements, mechanism of TEOS hydrolyzation and succedent condensation polymerization was inferred. With the adding of ammonia, OH^- anion attacks Si atomic nucleus directly and makes it showing negative electricity. Therefore the electron cloud shifts to the OR group on the other side. This weakens the Si-O bond and results in the removal of the OR group. Furthermore, silanol, generated from TEOS hydrolyzation, attracts Si-OR or other Si-OH around; thereby resulting rapid dehydration or dealcohol between molecular. So the condensation polymerization rate is elevated, and Si-O-Si bond comes into being. Lastly, cross-linking reaction among Si-O-Si bonds forms the particle.

Abstract: Spinel LiMn₂O₄ material is one of the lithium-ion battery cathodes. It is cheap, nontoxic, and safe in use. This cathode material, Li_1.06Mn₂O₄ was synthesized by using solid state reaction and two different starting materials. One was the Mn₂O₃ made from the industrial manganese carbonate with different contents of potassium, and the other was the high-purity Mn₂O₃ into which the same amount of potassium in the form of K₂CO₃ was added to form the K-doped spinel Li_1.06Mn₂O_4. These two kinds of LiMn₂O₄ materials were characterized by XRD, SEM and electrochemical performance analysis. The results showed that the initial discharge capacity of the former cathode materials decreased gradually and the cycle performance was improved with the amount of potassium increasing. The Li_1.06Mn₂O₄ with a content of 192.2 μg.g^-1 of potassium presented the optimized electrochemical performances, with an initial discharge capacity of 128.974mAh.g^-1, and a capacity retention rate of 89.90% after 50 cycles. The initial discharge capacity of doped Li_1.06Mn₂O₄ dropped rapidly with the doping amount increasing and the capacity retention rate was not as good as that of the Mn₂O₃ made from the industrial manganese carbonate with different contents of potassium.

Abstract: Silicon postsare fabricated by inductively coupled plasmaetching (ICP). Then, a SU-8 layer is spin-coated. During the photolithography, the opening areas of mask are aligned to the top surface of the underlying silicon posts.SU-8 fibers that interconnect the underlying silicon postsare created due to the mask-induced diffraction effect. After pyrolysis, SU-8 photoresist is transformedinto carbon, and as the results, carbon fibers that interconnect the underlying silicon postsare created.

Abstract: The quantum confinement Stark effect of three types of GaInNAs quantum wells, namely single square quantum well, stepped quantum wells and coupled quantum wells, is investigated using the band anti-crossing model. The comparison between experimental observation and modeling result validate the modeling process. The effects of the external electric field and localized N states on the quantized energy shifts of these three structures are compared and analyzed. The external electric field applied to the QW not only changes the potential profile but also modulates the localized N states, which causes band gap energy shifts and increase of electron effective mass.

Abstract: As a preferred technology to enhance oilfield energy production, well stimulation has and will continue to have an important role in fulfilling the worlds future energy needs. Mud acid is a conventional acid system that reacts with most injurants and removes damages. However, fast reaction rate with minerals will lead to high leak-off velocity, great possibility of secondary and tertiary precipitation, lower effect of corrosion inhibitor in high temperature as well as short efficient operating range. Therefore, new kinds of acid system are required to cope with these problems above. This paper proposed three acid system with the similarity of fluorine ammonium compounds for sandstone acidizing ammonium hydrogen fluoride (AHF), ammonium fluotitanate (AFT), and ammonium fluoroborate system (AFB). Chemical structures, acidity test and solubility tests have proved the feasibility. Then, performance comparisons are conducted to prove the advantages over mud acid system.

Abstract: Based on the removal of SO₂ as the research background, this paper focuses on the research of mono-component experiment and orthogonal experiment of compound sulfur-fixing agent composed of shell powder and red mud (at the mass ratio of 8:2) at the temperature of 1000°C and Ca/S was 2.0, by adding manganese dioxide, fly ash, magnesium oxide and potassium carbonate as the sulfur-fixing additive. The experimental results showed that the sulfur fixation capacity of desulfurizer is increased to different extents and the optimal ratio to additive is obtained after addition of the additive.

Abstract: NiTi shape memory alloy was potentiostatically anodized in a molybdate electrolyte containing ammoniac ion to form a thick and uniform oxide layer. The oxide layer was characterized by SEM, XRD, EPMA, XPS and potentiodynamic polarization test. It was found that the as-prepared coating is a thick (approx. 40 μm), smooth and dense oxide layer, and is free of cracks and porous defects. Moreover, the surface analyses revealed that the anodic oxidation at 60 mV potential (SCE) reduces significantly the proportion of Ni in the outmost surface layer, and the atomic ratio of Ti and Ni elements is raised from 1:1 to 9.7:1. The as-prepared coating was primarily composed of noncrystalline TiO₂ on the outermost surface with a small quantity of Ni (OH)₂. Potentiodynamic polarization tests in Fusayama artificial saliva pH 6.2 demonstrated that the oxide layer presents a significant increase in breakdown potential due to titanium enrichment.

Abstract: The prepared Mn-Ce/CNTs catalyst was tested with Temperature-Programmed Desorption (TPD) in this experiment. The adsorption – desorption of NO, NH₃, O₂ on the surface of catalyst were studied and the mechanism of SCR was analyzed. The conclusions were as follows: NH₃was easily absorbed on the surface of Mn-Ce/CNTs catalyst for its significant competitive advantage; it can restrain the absorption of NO. The adsorption performance of NH₃ on catalyst surface was far greater than NO. When NO, O₂ adsorbed on the catalyst at the same time, the desorption amount of NO from catalyst significantly was less than the NO absorbed only. This shows that the O₂ can promote the adsorption of NO on the catalyst in SCR system.

Abstract: By means of complex variable functions, symmetrical dynamic extension issues of mode III interface crack were researched. The problems considered can be very facilely transformed into Riemann-Hilbert problem by the approaches of self-similar functions, and the general expressions of analytical solutions of the stresses, displacements and dynamic stress intensity factors for the edges of symmetrical mode III interface crack subjected to motive variable loadings Pt⁴/x⁴ and Px⁵/t⁴ were attained, respectively. After those solutions were utilized by superposition theorem, the solutions of arbitrary complex problems could be acquired.

Abstract: A series of UV-PUA films with different active diluents were prepared, The effect of the content of active diluent TPGDA or TMPTA on Photopolymerization kinetics and Mechanical properties was studied. The effect of formulation on mechanical properties was investigated. The results showed that when the content of oligomer PUA was 40%-45%, the content of HEA was 8%-10%, the content of TPGDA was 10%-14% and the content of TMPTA was 18%-25% ,PUA films with good mechanical properties were obtained.