ZnO films on transferable and low thermal resistance graphite substrate grown by ultrasonic spray pyrolysis

ZnO thin films were deposited on graphite substrates by ultrasonic spray pyrolysis method with Zn(CH 3 COO) 2 ·2H 2 O aqueous solution as precursor. The crystalline structure, morphology, and optical properties of the as-grown ZnO films were investigated systematically as a function of deposition temperature and growth time. Near-band edge ultraviolet(UV) emission was observed in room temperature photoluminescence spectra for the optimized samples, yet the usually observed defect related deep level emissions were nearly undetectable, indicating that high optical quality ZnO thin fi lms could be achieved via this ultrasonic spray pyrolysis method. Considering the features of transferable and low thermal resistance of the graphite substrates, the achievement will be of special interest for the development of high-power semiconductor devices with suffi cient power durability.     

可调卫燃带对燃煤锅炉热力特性的影响

介绍了可调卫燃带的概念与工作原理，并采用校核热力计算的方法，详细研究了煤种、负荷变化时可调卫燃带对炉膛吸热量、汽温、炉膛平均烟温、炉膛出日烟温、主要受热面进出日烟温等参数的影响。计算表明：可调卫燃带可使锅炉在更宽广的负荷范围内维持额定汽温：可提高低负荷时的热空气温度，可作为改善锅炉热力特性的一种有效调节手段。     

可逆式催化燃烧器的热波特性

为了减少大气中VOC排放,利用了一种周期性改变流向的催化燃烧反应器——可逆式催化燃烧器进行了模拟实验,对其性能进行了系统的研究,得到了各种热波波形曲线并对影响热波特性的主要因素进行了分析,结果表明,凡是影响一个周期内反应器热平衡的操作参数都有可能显著地影响反应段的温度水平,为这一类反应器的科学设计、优化操作和模型化研究奠定了实验基础。     

氧化铝缓冲层对ZnO薄膜性质的影响

采用反应磁控溅射的方法在石英衬底上制备了一层AI2O3薄膜,并将其作为后续ZnO薄膜生长的缓冲层.然后,采用反应磁控溅射的方法在AI2O3缓冲层上制备了ZnO薄膜.对比研究了引入Al2O3缓冲层前后,ZnO薄膜的结构和光学特性.通过引入Al2O3缓冲层,发现ZnO薄膜样品的(002)方向X射线衍射峰的半峰宽(FWHM)明显减小,光致发光谱中与缺陷相关的可见发光峰强度明显减弱,吸收光谱中的吸收边变得更加陡峭.这些结果表明引入Al2Q3缓冲层后,ZnO薄膜的结构和光学特性得到了很大改善,为制备高质量ZnO薄膜提供了参考.     

Kinetics of Fe_3O_4 formation by air oxidation

1　INTRODUCTIONFe3O4 hasanumberofnovelpropertiesandper formances ,itsuniquemagnetic ,thermalandtribolog icalpropertiesmakeitanewtypeofmaterialspromis inginvariousapplicationssuchaspigment,toner ,in formationstorage ,ferrofluids ,bioprocessing ,elec tronicsandcatalyst[1,2 ] .Owingtothewideapplica tion ,majorityofresearchersfocusedontheprepara tionmethodsofmagnetite[310 ] ,however ,themech anismandkineticsofFe3O4 formationwerescarcelystudied .Thekineticsandmechanismofoxyhydrox idesformatio…     

高级氧化技术降解卤乙酸效果及动力学研究

为降低预氯化过程中产生的消毒副产物带来的饮用水不安全性,探讨高级氧化技术降解消毒副产物中的卤乙酸的效果并进行反应动力学分析.结果表明,当紫外光强为1048μW/cm2,双氧水投加量为70 mg/L,UV/H2O2工艺对二氯乙酸去除率为84.58%,紫外光强为183μW/cm2,双氧水投加量为141.51 mg/L,O3累计投加量为5 mg/L,UV/H2O2/O3工艺对二氯乙酸的去除率为80.37%,分析两种工艺的反应动力学规律,试验拟合反应速率k与双氧水投加量的反应动力学方程模型分别为:k=0.0002[H2O2]和k=0.0008[H2O2]0.5403.     

真空紫外/氯高级氧化法去除水中卡马西平试验研究

为去除水中典型难降解污染物卡马西平(CBZ),构建了真空紫外/氯高级氧化体系,考察基于真空紫外或自由氯的不同氧化体系中CBZ去除效能的差异;探究pH值、自由氯投加量、水中重碳酸盐、腐殖酸对真空紫外/氯体系去除CBZ效果的影响及自由氯在该体系中的衰减情况;通过自由基淬灭试验,进一步探究在真空紫外/氯体系中氧化CBZ的主要活性物质。结果表明:在pH值为6,氯投加量为8 mg/L,CBZ初始浓度为30μmol/L时,真空紫外/氯体系中反应16 min后CBZ去除率超过99.5%;在相同条件下,真空紫外/氯体系去除CBZ的速率常数是真空紫外体系、UV/氯体系的1.75、5.30倍,真空紫外和自由氯具有协同去除CBZ的作用;在酸性条件下,CBZ的去除效果较好,最佳反应pH值为6;自由氯投加量是影响CBZ降解速率的重要因素,最佳自由氯投加量为8 mg/L;而水中重碳酸盐和天然有机物对CBZ的去除均呈现抑制作用;真空紫外/氯体系降解CBZ的过程中,自由氯消耗主要为紫外光激发消耗,而与CBZ及降解产物反应较为微弱,该体系存在HO·和Cl·的氧化作用及直接光解作用。     

寒冷地区坝内垫层管运行期温度效应及保温措施研究(研究生论坛）

为研究寒冷地区温度变化及保温措施对坝内垫层管外包混凝土开裂状况的影响,本文基于混凝土塑性损伤模型,考虑运行期的温度作用,对某水电站坝内垫层管进行了非线性有限元分析。结果表明：由于垫层的铺设,正常运行工况下管道混凝土几乎无损伤,管道表面不会出现宏观裂缝;但在温降工况下管道顶部混凝土损伤较严重,而在温升工况下管道底部混凝土损伤更明显,相应损伤区域的钢筋应力也明显增加;坝面保温板的铺设能够有效降低结构所承担的温度荷载,改善混凝土损伤状况,降低钢筋应力,且随着保温板厚度的增加其作用效果逐渐显著,但当增加到一定程度后,其作用效果趋于稳定,同时考虑投资等工程实际情况,不宜过度增加保温板厚度,建议保温板厚度由裂缝宽度控制。     

Fabrication of Ceramic Composites by Directed Metal Oxidation

To explain the growth mechanism of Al2O3/Al Lanxide composites , the dynamics of the directed oxidation of Al-Mg-Si alloys are analyzed. The experimental methods to produce Lanxide composites by directed oxidation of metal melts at high temperatures are presented. The effect of the processing factors on the microstructures and properties of Al2O3/ Al composites and enforced Al2O3/Al composites is also analyzed. Compared with sintering ceramic composites, the advantages of Lanxide process and Lanxide materials are as following : it is a near net shaped process ; the process is very simple ; the microstructures and properties of Lanxide materials can be adjusted ; and this process can be used to infiltrate ceramic fiber or particle preforms.     

阻燃服用外层织物的热防护性能分析

取19种不同成分与组织结构的阻燃隔热面料作为研究对象,对织物的基本参数进行了测试,并对织物经热防护性能测试后的升温时间和质量损失率作了测定与分析.结果表明:同等条件下阻燃高聚物纤维织物的热防护性能远优于经过阻燃后整理的阻燃棉及改性腈纶织物,说明纤维种类是影响织物热防护性能的关键因素;织物厚度与其热防护性能关系密切,厚度越厚,织物与火焰接触时升温时间越长,质量损失率越小,热防护性能越好.     

阴阳极室同时氧化对煤气废水处理效果的研究

在棉布隔膜电解槽中,使用Ti/IrO2/RuO2阳极、自制的碳/聚四氟乙烯(C/PTFE)充氧阴极,研究了电化学催化氧化降解煤气废水的效果.结果表明,在阴极室,C/PTFE充氧阴极通过外界曝气提供的O2在阴极还原产生H2O2,采用电子自旋共振法(ESR)阴极室中检测到羟自由基(HO.)的存在.煤气废水中挥发酚和COD去除率均随电解时间的延长而升高、随电流密度的增加而升高,电解质浓度对煤气废水中挥发酚和COD的去除情况没有明显规律性的影响.煤气废水的降解是在阳极的直接、间接氧化及阴极产生的H2O2、HO.和O2-.自由基的氧化共同作用下完成的,阴、阳极室同时电催化氧化降解煤气废水取得了较好的效果.     

高级氧化工艺对水中邻苯二甲酸二丁酯的降解研究

采用UV、O3和UV/O3联用工艺对水中邻苯二甲酸二丁酯(DBP)的降解效果和降解产物进行研究,探讨了O3初始浓度、DBP初始浓度、pH值等因素对氧化降解DBP的影响.结果表明:UV本身对DBP的去除贡献率不大,UV/O3联用工艺对DBP的去除效果略优于单独O3氧化,提高体系的初始pH值和O3浓度有利于DBP的降解;采用GC-MS分析方法对DBP O3氧化中间产物进行分析,得出DBP可能的降解途径.     

Thickness dependence of the initial oxidation behaviors of Gd films grown on Si by laser molecular beam epitaxy

Gd thin films with different thickness(about 10 nm and 0.5 nm)were deposited on Si(100)by laser molecular beam epitaxy(LMBE).Thickness dependence of the initial oxidation behaviors of Gd films was studied based on the in situ X-ray photoelectron spectroscopy(XPS)and ultraviolet photoelectron spectroscopy(UPS)analysis under ultra-high vacuum(UHV)condition.When the thin film is around 10 nm,the XPS results show that Gd is extremely reactive with oxygen forming Gd oxides and the oxides of Gd are easily hygroscopic.The UPS results show that the Gd 4f has a double-peak structure and the double-peak structure of Gd 4f evolves into a single-peak feature after exposing to air.When the thickness of the Gd film decreases to about 0.5 nm,the reactivity of Gd film with oxygen is decreased by the diffusion of Si component into Gd layers based on the XPS and UPS results.It is suggested that the silicon atoms segregate at the grain boundaries of Gd film to form a barrier,which block the further diffusion of oxygen and water vapor into the Gd layers.     

Microcrystalline coatings deposited by series double-pole electro-pulse discharge and its high-temperature oxidation behavior

A new technique——series electro-pulse discharge (SEPD)——was developed as asurface coating process. In this process, both positive and negative poles of a pulse power were used as the depositing electrodes and the substrate alloy was used as an induction electrode. The physical process for such SEPD was tested by measuring the relationship between the discharge voltages and gaps in a pin-plate-pin system. Microcrystalline Ni20Cr alloy coatings and oxide-dispersed Ni20Cr alloy coatings were prepared on Ni20Cr alloy surface by using a vibrating SEPD device. Oxidation at 950℃ in ambient air showed that the microcrystalline Ni20Cr alloy coatings greatly improved the oxidation resistance of the substrate alloy. The addition of dispersed Y2O3 nano-particles into the microcrystalline coatings was found to further reduce the oxidation rate and enhance the oxide spallation resistance.     

Similarity solutions for the mixed convection flow over a vertical plate with thermal radiation

The steady laminar boundary layer flow adjacent to a vertical plate with prescribed surface temperature immersed in an incompressible viscous fluid,where the effect of thermal radiation was taken into consideration,was investigated.The governing partial differential equations were transformed into a system of ordinary differential equations using similarity transformation,before being solved numerically by the shooting method.Both assisting and opposing buoyant flows were considered.It is found that dual...     

硫酸锰热解制备Mn2O3以及用热解尾气浸出低品位软锰矿的实验研究

用硫酸锰(MnSO4)高温热解的方法制备了三氧化二锰,并考察了热解制备过程中产生的尾气浸出低品位软锰矿的可行性。热解实验表明,850℃是硫酸锰热解制备三氧化二锰的最佳温度。硫酸锰在850℃热解所得三氧化二锰产品的锰含量为68.93%。产品的XRD和FTIR表征结果表明,热解产物为单一相的立方体结构三氧化二锰。尾气测定结果表明硫酸锰热解制备三氧化二锰时释放出的尾气中含有SO2和SO3, 两者摩尔比约为7:1。浸出实验结果表明利用热解尾气浸出软锰矿是完全可行的。在温度为60℃,初始硫酸浓度为0.1mol/L时,尾气中SOx（SO2和SO3）的吸收率达到99.73 %,软锰矿的锰浸出率达到94.37 %。该工艺不仅可以避免液相制备方法中废水的问题,还可以使得热解制备过程产生的尾气和低品位软锰矿同时得到资源化利用。     

Aerobic oxidation behavior of α-ionone catalyzed by N-hydroxyphthalimide combined with acetylacetone cobalt(Ⅱ)

A practical catalytic method to oxidize α-ionone with molecular oxygen using N-hydroxyphthalimide(NHPI) combined with acetylaeetone cobatt(Ⅱ) (Co(acac)2) was developed, and the probable catalytic mechanism was proposed. The influences of the reaction conditions on conversion of α-ionone and the selectivity of the major product (5-keto-ct-ionone) were investigated, and the technical parameters for 5-keto-α-ionone were optimized. The results show that the primary product is 5-keto-α-ionone, and by-products include epoxy-α-ionone, as well as rearrangement products 4-keto-β-ionone and epoxy-β-ionone, which are characterized by infrared spectra, proton nuclear magnetic resonance spectra, mass spectra and elemental analysis. The selectivity of 5-keto-α-ionone and the conversion of α-ionone are 55.0% and 97.0%, respectively, when 30%(molar fraction) NHPI, 1.0%(molar fraction) Co(acac)2 and no solvent are employed under O2 pressure of 1.0 MPa and the reaction temperature of 65℃ for 11 h. The procedure shows good reproducibility in the parallel experiments.     

Bioactive titanium metal surfaces with antimicrobial properties prepared by anodic oxidation treatment

In order to endow titanium metals with bioactivity and antimicrobial properties, titanium plates were subjected to anodic oxidation treatment in NaCl solutions in this study. The treated titanium metals could induce apatite formation in the fast calcification solution, and osteoblasts on the treated titanium surfaces proliferated well as those on the untreated titanium metal surfaces. The treated metals could inhibit S. aureus growth in the microbial culture experiments. It was assumed that Ti-OH groups and Ti-Cl groups formed on the treated titanium surface were responsible for the bioactivity and antimicrobial properties of the metals. The anodic oxidation treatment was an effective way to prepare bioactive titanium surfaces with antimicrobial properties. Supported by the National Natural Science Foundation of China (Grant Nos. 50672062 and 30870615), Key Programs for Science and Technology Development of Sichuan Province, China (Grant No. 2008SZ0104) and Sichuan Youth Science & Technology Foundation, China (Grant No. 09ZQ026-033)     

Preparation of nitric humic acid by catalytic oxidation from Guizhou coal with catalysts

Nitric humic acid was prepared by catalytic oxidation between nitric acid and Guizhou coal,with added catalysts.We investigated catalytic oxidation processes and the factors that affect the reactions.T...