Effect of process parameters on laser damage threshold of TiO2 coatings

We investigate the laser damage behaviour of an electron-beam-deposited TiO2 monolayer at different process parameters. The optical properties, chemical composition, surface defects, absorption and laser-induced damage threshold (LIDT) of Elms are measured. It is found that TiO2 Elms with the minimum absorption and the highest LIDT can be fabricated using a TiO2 starting material after annealing. LIDT is mainly related to absorption and is influenced by the non-stoichiometric defects for TiO2 films. Surface defects show no evident effects on LIDT in this experiment.

等离子体喷涂涂层细观结构与工艺相关性研究

采用改进的颗粒沉积模型和一种新建议的循环算法，利用数值方法模拟了等离子体喷涂中涂层的生长过程及涂层的细观结构。数值模拟，主要包括了陶瓷液滴的高速变形与凝固、涂层材料的堆积、涂层中细胞空洞的形成与温度场的迭代计算等过程。研究结果表明，涂层中孔隙率的分布与一些关键工艺参数和基底表面状态等有关，液态陶瓷颗粒的直径和飞行速度的加大会引起涂层内孔隙率的增加，而基体温度和表面粗糙度的升高则有利于提高涂层的致密度。本文的研究结果将有助于定量或半定量地优化选取工艺参数以便获得所需的涂层结构和改善涂层的力学性能。

Amorphous Coatings Deposited on Aluminum Alloy by Plasma Electrolytic Oxidation

Amorphous [Al-Si-O] coatings were deposited on aluminum alloy by plasma electrolytic oxidation (PEO). The process parameters, composition, micrograph, and mechanical property of PEO amorphous coatings were investigated. It is found that the growth rate of PEO coatings reaches 4.44 mu m/min if the current density is 0.9 mA/mm(2). XRD results show that the PEO coatings are amorphous in the current density range of 0.3-0.9 mA/mm(2). EDS results show that the coatings are composed of O, Si and At elements. SEM results show that the coatings are porous. Nano indentation results show that the hardness of the coatings is about 3 - 4 times of that of the substrate, while the elastic modulus is about the same with the substrate. Furthermore, a formation mechanism of amorphous PEO coatings was proposed.

喷射成形工艺参数及热挤压制度对8009耐热铝合金的组织及性能的影响

采用喷射成形方法制备了Al-8.5Fe-1.4V-1.7Si(8009)耐热铝合金，研究了喷射成形工艺参数及沉积坯件的热挤压工艺对材料的微观组织及性能的影响。结果表明：喷射成形工艺能够有效地抑制8009合金中粗大的富铁相的析出，获得均匀细小的组织；当射成形工艺参数选择适当时，沉积坯件具有良好的成形性与致密度，在随后的热挤压过程中，通过较低的挤压比即可使材料达到全致密。合金经过热挤压后，在室温及高温下均具有良好的力学性能。

Planar waveguides formed in a new chemically stable Er3+/Yb3+ co-doped phosphate glass

A new Er(3+)/Yb(3+) co-doped phosphate glass has been prepared, which exhibits good chemical durability and spectralproperties. Planar graded index waveguides have been fabricated in the glass by (Ag+)-Na(+) ion exchange in a mixed melt of silver nitrate and potassium nitrate. Ion exchange is carried out by varying the process parameters such as temperature, diffusion time, and molten salt compositions. The diffusion parameters, diffusion coefficients, and activation energy are determined by the guidelines of fabricated waveguides, which are determined by the input prism coupling technique.

Emitter of hetero-junction solar cells created using pulsed rapid thermal annealing

In this paper, we use a pulsed rapid thermal processing (RTP) approach to create an emitter layer of hetero-junction solar cell. The process parameters and crystallization behaviour are studied. The structural, optical and electric properties of the crystallized films are also investigated. Both the depth of PN junction and the conductivity of the emitter layer increase with the number of RTP pulses increasing. Simulation results show that efficiencies of such solar cells can exceed 15% with a lower interface recombination rate, but the highest efficiency is 11.65% in our experiments.

OLAND生物脱氮系统运行条件及其微生物群落结构的研究

OLAND两阶段生物脱氮系统是一项正在开发且极具应用前景的处理高氨氮、低COD废水的新技术。在实验室水平，对OLAND系统限氧亚硝化阶段MBR反应器和厌氧氨氧化阶段SBR反应器的启动和运行进行了系统研究。MBR反应器控制参数在DO0.1-0.3mg/L，pH7.8±0.1，温度30±0.5℃，SRT无穷大的条件下，可实现在较高的容积负荷By＝IO00mgN／L，水力停留时间HRT：ld下稳定的亚硝酸型硝化，使NH4+-N和NO2-N的出水比例达到理想的比值（1:1.20±0.20），保证厌氧氨氧化阶段SBR反应器的理想进水；SBR反应器在完全厌氧、pH7.8-8.2，温度30±0．5℃，SRT无穷大的条件下，无需外加任何有机碳源，在较高总氮负荷550mgN／L下，可实现NH4+-N和NO2--N同时稳定的去除，二者的消耗比例为1:（1.21±0.05），总氮去除率高达92％。采用巢式PCR、DGGE、 FISH等分子技术对MBR反应器硝化菌群随溶解氧的动态变化规律和SBR反应器厌氧氨氧化菌群结构、组成进行了研究，并探讨了硝化菌群与氮素组成变化之间的内在联系。结果表明：在限氧亚硝化阶段硝化菌群中氨氧化菌受溶解氧浓度的影响较大，其种群结构从反应器启动初期到稳定后期发生了非常明显的变化。亚硝酸氧化菌NOB的种群组成受溶氧影响并不明显，从启动初期到稳定后期其种群结构无明显变化。硝化菌群中氨氧化菌 AOB与亚硝酸氧化菌NOB的数量比例关系随溶解氧的降低而不断升高，从最初的3.6:1升高到稳定后期的5.5:1。MBR反应器优势硝化菌群主要由A、B、C三类氨氧化菌和硝化杆菌D、硝化螺菌F组成，其中优势菌C为维持MBR反应器稳定出水比例的主要功能菌。硝化菌群组成和结构的变化，带来了不同N素之间组成和比例的规律性变化。厌氧氨氧化阶段基本由厌氧氨氧化菌AnAOB和ANAMMOX两类菌组成，二者空间结构紧密，在反应器中的活菌数量比例分别为55％和42％。厌氧氨氧化菌AnAOB种群多样性相对比较丰富，主要由条带I和H所代表的两种优势菌组成；ANAMMOX菌种群多样性变化较小，其种群主要由优势菌K和J组成。对MBR和SBR反应器中的优势菌进行了克隆、测序和系统发育学分析，结果表明：限氧亚硝化阶段MBR反应器启动初期的优势菌A属于Nitrosomonadaceae科，是否是一个新属，还有待于进一步鉴定。运行中期优势菌B与Nitroso）nonaseurooaea亲缘关系最近，同源性高达99.1％，暂命名为Nilrosomonas sp.BI。稳定后期优势菌C与Nitrosomonas eutroPha亲缘关系最近，同源性为96.3％，暂命名为Nifrosomonas sp．cl。硝化杆菌属优势菌D与Nitrobacter alkalicus、Nitrobacter hambllrgensts和Nitlobac招rwinograsky 亲缘关系较近，同源性分别为95.5-97％、96.5～97％和95.8～96.8％。SBR反应器中AnAOB优势菌I与MBR反应器优势菌B亲缘关系最近，同源性高达98.7％，与Nitlosomonas euroPaea同源性为98.3％。根据序列比较和生理特性分析，优势菌I与优势菌B应为Nitrosomonas属两个不同的种，暂将优势菌I命名为Nitrosomonas sp．II。优势菌H与MBR反应器优势菌C亲缘关系最近，同源性达97.9％，与Nitrosomonas eutropha同源性为96.3％。结合其生理特性分析，二者应为Nitrosomonas属两个不同的种，暂将优势菌H命名为Nitrosomollas sp．Hl。ANAMMox优势菌K与未培养的 Planctomycete和已鉴定的另一种ANAMMoX菌尤uenenia sf况ttgartiensis亲缘关系较近，同源性分别为99.8％和96.6％。优势菌J与Gen bank收录的所有菌的相似性均低于76％，说明该菌是OLAND系统厌氧氨氧化阶段比较独特的菌，是迄今为止在厌氧反应过程中未发现的一个新菌。

Size modification of Au nanoparticles induced by slow highly charged ions Ar-40(q+) irradiation

Size modification of Au nanoparticles (NPs), deposited on the Au-thick film surface and irradiated by slow highly charged ions (SHCI) 40Arq+ (3 6 q 6 12) with fixed low dose of 4.3 1011 ions/cm2 and various energy ranging from 74.64 to 290.64 keV at room temperature (293.15 K), was investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The effect of projectile kinetic energy on the modified size of NPs was explored by an appropriate choice of the fixed process parameters such as ion flux, irradiation temperature, incident angle, irradiation time, etc. The morphological changes of NPs were interpreted by models involving collisional mixing, Ostwald ripening (OR) and inverse Ostwald ripening (IOR) of spherical NPs on a substrate. A critical kinetic energy as well as a critical potential energy of the projectile in the Au NPs size modification process were observed.

Preparation of uniform calcium alginate gel beads by membrane emulsification coupled with internal gelation

With the objective of making calcium alginate gel beads with small and uniform size, membrane emulsification coupled with internal gelation was proposed. Spherical gel beads with mean size of about 50 mum, and even smaller ones in water, and with narrow size distribution were successfully obtained. Experimental studies focusing mainly on the effect of process parameters on bead properties were performed. The size of the beads was mainly dependent on the diameter of the membrane pores. High transmembrane pressure made for large gel beads with wide size distribution. Low sodium alginate concentration produced nonspherical beads, whereas a high concentration was unsuitable for the production of small beads with narrow distribution. Thus 1.5% w/v was enough. A high surfactant concentration favored the formation of small beads, but the adverse effect on mass transfer should be considered in this novel process. (C) 2002 Wiley Periodicals, Inc.

Thermal barrier coating of lanthanum-zirconium-cerium composite oxide made by electron beam-physical vapor deposition

Lanthanum-zirconium-cerium composite oxide (La-2(Zr0.7Ce0.3)(2)O-7, LZ7C3) as a candidate material for thermal barrier coatings (TBCs) was prepared by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, thermophysical properties, surface and cross-sectional morphologies and cyclic oxidation behavior of the LZ7C3 coating were studied. The results indicated that LZ7C3 has a high phase stability between 298 K and 1573 K, and its linear thermal expansion coefficient (TEC) is similar to that of zirconia containing 8 wt% yttria (8YSZ). The thermal conductivity of LZ7C3 is 0.87 W m(-1) K-1 at 1273 K, which is almost 60% lower than that of 8YSZ. The deviation of coating composition from the ingot can be overcome by the addition of excess CeO2 and ZrO2 during ingot preparation or by adjusting the process parameters.

The thermal cycling behavior of Lanthanum-Cerium Oxide thermal barrier coating prepared by EB-PVD

Bulk material and coatings of Lanthanum-Cerium Oxide (La2Ce2O7) with a fluorite structure were studied as a candidate material for thermal barrier coating (TBC). It has been showed that such material has the properties of low thermal conductivity about four times lower than YSZ, the difference in the thermal expansion coefficient between La2Ce2O7 and bond coat is smaller than that of YSZ in TBC systems, high phase stability between room temperature and 1673 K, about 300 K higher than that of the YSZ. The coating prepared by electron beam physical vapor deposition (EB-PVD) showed that it has good thermal cycling behavior, implying that Such material can be a promising thermal barrier coating material. The deviation of coating composition from ingot can be overcome by the addition of excess La2O3 during ingot preparation and/or by adjusting the process parameters.

不同基板预热温度对激光金属沉积成形过程热应力影响的研究

研究不同基板预热温度对激光金属沉积成形过程热应力的影响,对于降低成形过程的热应力,抑制成形过程裂缝的产生,减小成形过程试样和基板的翘曲变形具有非常重要的意义。根据有限元分析中的"单元生死"技术,编程建立了基板预热对激光金属沉积成形过程热应力影响的三维多道多层数值模拟模型,详细分析了基板未预热和分别预热到200℃、300℃、400℃、500℃、600℃时对沉积成形过程VonMise’s热应力、X方向、Y方向以及Z方向热应力的影响。在与模拟过程相同的参数下,利用镍基合金粉末分别在基板未预热和分别预热到300℃、400℃、500℃、600℃时进行了成形试验,试验的结果跟数值模拟结果吻合较好。

Preparation and characterization of Pd-Ag alloy composite membrane with magnetron sputtering

A Pd-Ag (24 wt%) alloy composite membrane was prepared by the magnetron sputtering. A gamma-Al2O3 membrane was synthesized by the sol-gel method and used as substrate of the Pd-Ag alloy film. The process parameters of the magnetron sputtering were optimized as a function of the compactness of the Pd-Ag alloy film. The best membrane with a thickness of 1 mu m was produced with a sputtering pressure of 2.7 Pa and a substrate temperature of 400 degrees C. The membrane had an H-2/N-2 permselectivity of 51.5-1000 and an H-2 permeation rate of 0.036-1.17 x 10(-5)cm(3)/cm(2).s. Pa, depending on operating conditions.