Preparation and hydrogen gas sensitive characteristics of highly ordered titania nanotube arrays

In this paper, we report the growth and characteristics of titania nanotube arrays prepared by anodic oxidation and then annealed in an oxygen atmosphere at 500℃. The titania nanotube arrays presented high sensitivity to hydrogen gas. The crystalline phase of the samples was checked by X-ray diffraction （XRD）. The differences in the nanotubes morphology attributed to the etched samples due to anodization potential, reaction time and the electrolyte concentration were analyzed by scanning electron mi- croscopy （SEM）. The gas sensitive parameters of the samples were obtained from resistance, the response time and the recovery time at different temperatures.     

钛制备方法研究现状

本文综述了钛制备的各种方法：氧化钛的还原法、卤化钛的还原法、钛化合物的电解法和卤化钛的热分解法,并且分析了它们的特点和各自存在的问题。指出钛化合物电解法中的FFC工艺最有可能代替传统的克劳尔法,从而降低钛的成本。     

反应温度对水热合成二氧化钛微粒的影响

采用水热合成工艺,以钛酸丁酯(Ti(OC4H9)4)为前驱体,通过改变水热合成反应的温度,合成了不同晶型和形貌的二氧化钛(TiO2)微粒。使用扫描电子显微镜和X射线衍射仪对产物进行表征。结果表明:水热反应的温度对TiO2微粒的晶型、晶粒尺寸和形貌有较大影响。随着水热反应温度的增加,二氧化钛微粒的晶粒粒径越来越大,结晶程度越来越完整,形貌也越来越规则。当水热反应温度较低时(80℃),晶型以锐钛矿为主,衍射峰峰宽较宽,峰强也较弱,晶粒刚开始发育;随着反应温度增加,开始出现金红石晶型,衍射峰锐化,峰的强度增强,晶粒粒径增大,晶粒逐渐发育完全;当反应温度达到160℃时,以金红石晶型为主,晶粒发育完全,结晶完善。     

提高TiO2光催化处理废水效率的研究进展

简述了纳米TiO2光催化反应原理以及目前存在的问题,讨论了提高光催化活性的主要途径以及国内外的研究现状。提高光催化氧化活性主要通过2个途径:抑制电子-空穴对的复合以及拓宽光催化光谱响应范围。通过进一步的简化处理手段,有效利用太阳能,在解决环境污染问题尤其是废水处理方面具有广阔的发展前景。     

挤压速度对Ti6Al4V钛合金等通道转直角挤压过程 影响的数值模拟

采用Deform-3D有限元软件,对样品初始温度为900℃的Ti6Al4V钛合金等通道转直角挤压在0~5 mm/s的下压速度范围内进行了数值模拟。模拟计算结果表明：在相同的挤压速度下,试样通过转角后的温度降低速率减小;挤压速度越大,挤压过程所需的荷载越低,应变累积越小,等效应力越低,应力集中现象越少,挤压过程中试样的温降越小;本研究条件下,挤压速度值选定为5 mm/s。     

CuO和CuS量子点修饰单晶TiO2纳米棒阵列及光电转化性能表征简

通过浸渍沉积法,对TiO2纳米棒阵列进行了CuO和CuS量子点修饰。通过场发射扫描电镜可以清楚观察到量子点均匀分散于TiO2纳米棒表面,粒子尺寸随反应物中Cu2＋的浓度增加而增大,且CuS比CuO尺寸大,颗粒间团聚严重。修饰前后TiO2的晶相组成没有发生明显变化,均为正方金红石相,含铜量子点的结晶相也未出现。在模拟太阳光辐射下,少量的CuO和CuS量子点沉积都能显著提高复合体系的光电响应,最高短路光电流密度分别约为空白TiO2的5倍和3．5倍,说明表面量子点敏化提高了光致电荷分离与转移效率。过量的CuO和CuS沉积会导致粒子尺寸的增大和团聚,不利于和TiO2之间的电荷转移,光电流随之降低。另外,CuO敏化TiO2的光电转化性能和稳定性都要优于CuS,推测这是由于CuS粒子大,易团聚,并且在光照下容易得电子形成更加稳定的Cu2 S所致。     

Preparation and thermal stability on non-vacuum high temperature solar selective absorbing coatings

Spectrally selective TiAl/TiAlN/TiAlON/TiAlO coating was deposited on stainless steel and copper substrates using a multiarc ion plating system.The structure,morphology,optical reflectance and electrical resistivity were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),spectrophotometer and four-point probe meter,respectively.The results show that the coating exhibits high absorptance(―0.9) and low emittance(0.09―0.19).The coating remains stable in air up to 650℃ for 1h.These propert...     

Effect of an upward magnetic field on nanosized sulfide precipitation in ultra-low carbon steel

An induction levitation melting (ILM) refining process is performed to remove most microsized inclusions in ultra-low carbon steel (UCS). Nanosized, spheroid shaped sulfide precipitates remain dispersed in the UCS. During the ILM process, the UCS is molten and is rotated under an upward magnetic field. With the addition of Ti additives, the spinning molten steel under the upward magnetic field ejects particles because of resultant centrifugal, floating, and magnetic forces. Magnetic force plays a key role in removing sub-micrometer-sized particles, composed of porous aluminum titanate enwrapping alumina nuclei. Consequently, sulfide precipitates with sizes less than 50 nm remain dispersed in the steel matrix. These findings open a path to the fabrication of clean steel or steel bearing only a nanosized strengthening phase.     

Sintering behaviors and consolidation mechanism of high-chromium vanadium and titanium magnetite fines

To achieve high efficiency utilization of high-chromium vanadium–titanium magnetite (V–Ti–Cr) fines, an investigation of V–Ti–Cr fines was conducted using a sinter pot. The chemical composition, particle parameters, and granulation of V–Ti–Cr mixtures were analyzed, and the effects of sintering parameters on the sintering behaviors were investigated. The results indicated that the optimum quicklime dosage, mixture moisture, wetting time, and granulation time for V–Ti–Cr fines are 5wt%, 7.5wt%, 10 min, and 5–8 min, respectively. Meanwhile, the vertical sintering speed, yield, tumbler strength, and productivity gains were shown to be 21.28 mm/min, 60.50wt%, 58.26wt%, and 1.36 t·m-2·h-1, respectively. Furthermore, the consolidation mechanism of V–Ti–Cr fines was clarified, revealing that the consolidation of a V–Ti–Cr sinter requires an approximately 14vol% calcium ferrite liquid-state, an approximately 15vol% silicate liquid-state, a solid-state reaction, and the recrystallization of magnetite. Compared to an ordinary sinter, calcium ferrite content in a V–Ti–Cr sinter is lower, while the perovskite content is higher, possibly resulting in unsatisfactory sinter outcomes.     

纳米二氧化钛-硅藻土复合材料的制备及性能

用酸性红3R染料溶液模拟染料废水,在可见光强度为86200 uw/cm2,紫外线强度为465 uw/cm2的太阳光照射下,研究了纳米TiO2/硅藻土复合材料制备最佳条件的选择.通过SEM、XRD、EDS和IR对样品进行了表征,同时探讨了体系pH,光照时间以及染料初始浓度对光催化效果的影响.结果显示,当酸性水解时间在75 min、中性回流时间为2小时、二氧化钛与硅藻土比为1:3的复合材料催化效果最佳.当体系溶液pH=3时,光照时间越长,染料初始浓度越低,光催化效果越好