Cu/Si载氧体氧解耦反应动力学研究

通过机械混合法制备了Cu/Si载氧体并进行了表征,利用热重技术研究了5,10,15和20℃·min~(-1)的升温速率下载氧体的氧解耦反应特性,并采用Coats-Redfern和Starink两种方法进行了动力学分析.载氧体物相组成主要包括CuO和SiO_2,制备过程中Cu-Si的复合化合物未形成;颗粒中CuO和SiO_2交错分布,SiO_2的添加能有效抑制铜氧化物晶粒的长大,避免烧结团聚现象的发生;氧解耦反应达到起始反应温度后,始终维持较高的反应速率直至反应完成;随升温速率的增加,载氧体氧解耦反应起始、终止温度都往高温方向移动,最大反应速率数值逐渐增大.两种方法确定的反应机理函数相同,均为成核和核增长模型R3;Starink法求得的活化能较Coats-Redfern法数值偏大.     

半刚性基层沥青路面疲劳裂缝扩展与寿命预估研究

以疲劳断裂力学理论和材料试验为基础,对半刚性基层沥青路面裂缝的扩展行为进行系统研究,分析了裂缝尖端的应力强度因子变化规律和偏荷载作用下各影响因素对疲劳寿命的影响;结合路面结构初始状态的荷载响应,回归得到了路面的疲劳寿命预估方程。结果表明,路面疲劳主要是由偏荷载作用于横向裂缝导致,疲劳寿命随面层整体模量和轴载增长而递减,随基层模量、路基模量、中面层厚度、基层厚度增长和车速而递增,随下面层厚度的增长先减后增。回归得到的疲劳寿命预估方程考虑的影响因素更加全面,为我国路面结构设计和科研提供了理论支持和补充。     

含焦宝石的陶瓷支撑剂的制备及性能

以铝矾土和焦宝石为原料,以锰粉为烧结助剂,制备高强度低密度支撑剂,并对相关性能进行研究。结果表明:随着铝矾土和焦宝石制备的陶瓷支撑剂配方中铝含量的不同,其最佳烧结温度范围略有不同,最佳的烧结时间也存在差异。在微观结构上,陶粒的强度主要由刚玉骨架提供,当铝含量降低时,陶粒中虽然会出现部分莫来石相,但并不会影响其性能,说明低铝含量铝矾土可用于制备刚玉-莫来石质陶粒支撑剂。     

Nitrate-dependent biodegradation of quinoline,isoquinoline, and 2-methylquinoline by acclimated activated sludge

The anaerobic degradation of quinoline, isoquinoline and 2-methylquinoline was investigated under nitrate-reducing conditions with acclimated activated sludge. Quinoline was completely transformed during degradation with an optimum COD/NO₃–N ratio of 7. Isoquinoline and 2-methylquinoline were also completely transformed; however, nitrate consumption was much lower with the optimum COD/NO₃–N ratios being in the ranges of 83–92 and 21–26, respectively. GC-MS analyses showed that during degradation, quinoline and isoquinoline were transformed by hydroxylation into 2(1H)-quinolinone and 1(2H)-isoquinolinone, respectively. While quinoline was completely mineralized, only 92% of isoquinoline was mineralized, and 1(2H)-isoquinolinone remained in the effluent. 2-Methylquinoline was transformed by hydrogenation to 1,2,3,4-tetrahydro-2-methyl-quinoline, and further degradation resulted in cleavage of the heterocyclic ring leaving 4-ethyl-benzenamine. Both the metabolites remained in the effluent, resulting in the low mineralization of 2-methylquinoline (58%). This is the first time that 2-methylquinoline is observed degradable under denitrifying conditions, and its metabolites are identified.     

新型淀粉-纤维素基微生物驱营养体系研究

开发了以淀粉-纤维素为基础的颗粒状本源微生物驱油营养剂,研究了营养剂对菌群的激活过程,并利用不同岩心模型评价了体系的封堵作用与驱油效果,探讨了该营养体系的调驱机理。结果表明,该体系在有氧和无氧条件下均能有效激活本源菌群,主要是烃类氧化菌和发酵细菌。微生物利用营养体系可产生表面活性物质（带C₈-C₁₂ 长链脂肪酸的鼠李糖脂）和生物气（CH₄和CO₂）,对原油有较好的乳化作用。非均质模型驱油结果表明,该体系不仅具有提高洗油效率的作用,同时可大幅提高波及效率,实验条件下可提高采收率12%~20%。现场试验表明,新体系能有效地封堵高渗透层,改变水驱方向,降水增油效果显著,投入产出比达1∶9以上。     

密炼机密炼辅助时间减少措施浅析

介绍了密炼配方时间减少的措施,通过密炼控制工艺的调整,在不增加硬件改造费用,不调整工艺配方的前提下,缩短密炼辅助时间,提高胶料产量,提高密炼机的利用效率.     

Effect of shot peening on surface mechanical properties of TiB<Subscript>2</Subscript>/Al composite

The influence of shot peening on the surface mechanical properties of the TiB₂/6351Al composite has been investigated. The microstructures were determined by X-ray diffraction line profile analysis. The results showed that the increment of hardness was about 50% in the top surface layer. The matrix proof stress σ _0.2 of the shot peened surface had been increased by 27% and the whole strength increment was about 21% by considering the contribution of the reinforcements. The domain size and the dislocation density in the strengthened surface were 55 nm and 3.67 × 10¹⁵ m⁻², respectively. The mechanical properties improvement of the modified surface was partially due to the reinforcements but mainly due to the fine domains, high value of dislocation density induced by shot peening.     

On the acid–base stability of Keggin Al<Subscript>13</Subscript> and Al<Subscript>30</Subscript> polymers in polyaluminum coagulants

The acid–base stabilities of Al₁₃ and Al₃₀ in polyaluminum coagulants during aging and after dosing into water were studied systematically using batch and flow-through acid–base titration experiments. The acid decomposition rates of both Al₁₃ and Al₃₀ increase rapidly with the decrease in solution pH. The acid decompositions of Al₁₃ and Al₃₀ with respect to H⁺ concentration are composed of two parallel first-order and second-order reactions, and the reaction orders are 1.169 and 1.005, respectively. The acid decomposition rates of Al₁₃ and Al₃₀ increase slightly when the temperature increases from 20 to ca. 35 °C, but decrease when the temperature increases further. Al₃₀ is more stable than Al₁₃ in acidic solution, and the stability difference increases as the pH decreases. Al₃₀ is more possible to become the dominant species in polyaluminum coagulants than Al₁₃. The acid catalyzed decomposition and followed by recrystallization to form bayerite is one of the main processes that are responsible for the decrease of Al₁₃ and Al₃₀ in polyaluminum coagulants during storage. The deprotonation and polymerization of Al₁₃ and Al₃₀ depend on solution pH. The hydrolysis products are positively charged, and consist mainly of repeated Al₁₃ and Al₃₀ units rather than amorphous Al(OH)₃ precipitates. Al₃₀ is less stable than Al₁₃ upon alkaline hydrolysis. Al₁₃ is stable at pH < 5.9, while Al₃₀ lose one proton at the pH 4.6–5.75. Al₁₃ and Al₃₀ lose respective 5 and 10 protons and form [Al₁₃] _n and [Al₃₀] _n clusters within the pH region of 5.9–6.25 and 5.75–6.65, respectively. This indicates that Al₃₀ is easier to aggregate than Al₁₃ at the acidic side, but [Al₁₃] _n is much easier to convert to Al_sol–gel than [Al₃₀] _n . Al₃₀ possesses better characteristics than Al₁₃ when used as coagulant because the hydrolysis products of Al₃₀ possess higher charges than that of Al₁₃, and [Al₃₀] _n clusters exist within a wider pH range.     

The mechanical response characteristics of sapphire under dynamic and quasi-static indentation loading

Sapphire is widely used as optical materials and substrate materials due to its excellent physical and chemical properties. The mechanism of crack propagation and fracture damage evolution has important significance for improving the manufacturing quality and application performance of sapphire parts. In this study, dynamic and quasi-static indentation tests have been performed on the c-plane and a-plane of sapphires by Hopkinson pressure bar tester and continuous indentation tester, respectively. The crack propagation path in sapphire has been captured by High-speed camera and the crack velocity has been calculated. The crack propagation and fracture damage evolution has been analyzed based on the fracture morphology of specimen. It was found that the bearing capacity of sapphire is related to the loading velocity, while the crack propagation is affected by the crystal orientation. Under the indentation loading, the cracks in sapphire first propagate steadily, and then the cracks begin to propagate uncontrollably after reaching the critical conditions, where the crack propagation velocity obviously increases, typically from 204?m/s to 1006?m/s (dynamic indentation) or from 0.0032?m/s to 820?m/s (quasi-static indentation). And the crack propagation velocity depends on the loading speed at stable stage. The r-planes of sapphire are weaker than other crystal planes and are prone to crack propagation.     

Deposition and characterization of epitaxial Ta-doped TiO2 films for ultraviolet photoelectric detectors

Undoped and tantalum-doped titania (TiO₂:Ta) films were synthesized via metalorganic chemical vapor deposition (MOCVD). The crystallization qualities, surface morphologies and optical properties of the deposited films were systematically characterized. The results indicated that the films having low doping levels were epitaxial anatase titania along [001] orientation with high transparency in visible region. The optical band gap could be modulated from 3.38 to 3.52?eV by controlling Ta doping levels. Ultraviolet (UV) photoelectric detectors with metal-semiconductor-metal (MSM) structure were designed and fabricated based on the undoped and Ta-doped films. The maximum spectral response of 32.3?A/W was detected at about 315?nm for the 1% Ta-doped TiO₂ film-based detector. The detectors based on the undoped and 1% Ta-doped TiO₂ films also presented good temporal responses and visible-blind characteristics, showing excellent UV light detection performances.