金属钛制备的研究现状与进展

阐述了现阶段制备金属钛的工艺和方法,包括Kroll法和Hunter法、FFC(Fray Farthing Chen)剑桥工艺、OS(Ono Suzuki)法、EMR/MSE(Electronically Mediated Reaction/Molten Salt Electrolysis)法、PRP(Preform Reduction Process)工艺、USTB(University of Science and Technology Beijing)工艺、SOM法、离子液体电析法以及其他方法。对各种钛制备工艺的优缺点进行了讨论,指出钛冶炼新工艺的工业化可行性与实现工业化生产所面临的问题。

合金钛粉制备铝合金钛剂的研究及应用

针对铝合金钛添加剂实收率波动的问题,研究了合金钛粉的粒度、种类、钛剂压制工艺及钛剂熔化工艺对钛添加剂的熔解速度和实收率的影响,选取了以合金钛粉为主,氢化脱氢钛粉+海绵钛粉+助熔剂为辅的配方,通过试验在合金钛粉粒度0.42~0.59 mm,液压机压强18~24 MPa,钛剂压块密度2.9~3.1 g/cm^(3)的条件下,钛元素的实收率为95%。

工业纯钛电子背散射衍射试样的制备

电子背散射衍射(EBSD)是一种较新的用来分析多晶体显微结构和组织的扫描电子显微镜技术,其试样的制备对其成像质量至关重要。通过对工业纯钛EBSD试样制备经验的总结,介绍了工业纯钛EBSD试样制备过程中切割、磨制、机械抛光、离子刻蚀和电解抛光等关键操作,提出了在EBSD试样制备过程中应注意的事项和技术要点。

铝粉除钒精四氯化钛过程控制优化研究

针对TiCl_(4)铝粉除钒工艺存在的稳定性差、精TiCl_(4)产品质量波动、产出率偏低等问题,对影响粗TiCl_(4)铝粉除钒过程的低价钛矿浆制备、蒸馏及精馏的关键因素进行研究。结果表明:在低价钛制备中,反应罐压力和停氯温度的控制是影响低价钛矿浆制备质量的关键因素,分别控制在100~110℃和-1.5~-1.8 kPa;蒸馏系统排渣比设定在1.6%,将残渣固含量控制在200~220 g/L范围,对精四氯化钛产量、质量影响显著;精馏系统残渣排放比例设定在2%,残渣中的固含量在30~45 g/L范围,有利于提高精四氯化钛产出率。

一种用于3D打印的钛合金粉末制备技术研究

钛合金粉末3D打印技术凭借着成本低廉、成型速度快、原料制备简单、制造的产品性能优良等特点,近年来已经成为很多领域重点使用和研究的对象。针对这样的发展需求,本文以3D打印的钛合金粉末制备技术为研究对象进行深入的探究。首先对3D打印的钛合金粉末制备的方法进行了简要说明和总结,然后对粉末钛合金3D打印的应用前景和未来的发展方向做了说明。

钛金属冶炼工艺新进展

叙述了Kroll法和FFC(Fray Farthing Chen)剑桥工艺制备钛的原理,并对制备钛的新工艺,包括OS(Ono Suzuki)法、EMR/MSE(Electronically Mediated Reaction/Molten Salt Electrolysis)法、PRP(Preform Reduction Process)工艺和USTB(University of Science and Technology Beijing)工艺的还原机理与工艺特点进行了总结。对各种钛制备工艺的优缺点进行了分析讨论,指出钛冶炼新工艺的工业化可行性与实现工业化生产所面临的问题。

钛合金电极成型模具凹模受力分析及设计计算

海绵钛塑性好,流动性差,电极压制过程中产生的侧压力较大,对凹模模套的强度和刚度提出了较高的要求,其壁厚的设计目前尚没有一个公认的计算方法。文中研究了钛合金电极成型模具的结构特点,对钛合金电极块成型过程中凹模受力情况进行了分析,依据强度与刚度的计算准则,推导了组合式模具凹模高度和壁厚的计算方法,为合理设计模具提供了依据。

BioLP中激光吸收层的制备及其表面处理研究

本文采用四种不同方法制备了生物激光打印技术中的镀钛基片,对基片表面形貌、粗糙度、附着力及生物相容性等性能进行了表征,在此基础上对比分析了加入表面活性剂和光诱导超亲水性两条途径对镀钛基片表面亲水处理的效果。实验结果表明,真空蒸镀法是生物激光打印技术中镀钛基片的最佳制备方法,在生物激光打印蛋白中可采取在溶液中加入表面活性剂的方法来提高基片表面亲水性。

多孔氧化钛储氢的研究

采用配体辅助模板法,以异丙醇钛为前体,使用不同碳链长度的烷基胺为模板剂来制备一系列不同比表面积和孔容的多孔氧化钛材料。采用X射线衍射,氮气吸附实验,透射电镜对所制取材料进行表征,并在77K的条件下测量所制取材料的储氢性能。结果表明,在材料中拥有最大比表面积的材料具有最高的储氢量,在77K和65大气压的条件下其重量和体积储氢量分别为3.92wt%和21.48kg/m3。

Enhanced photocatalytic properties of hierarchical nanostructured TiO_2 spheres synthesized with titanium powders

Using Ti powder as reagent, TiO 2 nanoneedle/nanoribbon spheres were prepared via hydrothermal method in NaOH solution. The samples were characterized by field emission scanning electron microscopy （FESEM）, transmission electron microscopy （TEM） with selected area electron diffraction （SAED）, X-ray diffraction （XRD）, and UV-visible light absorption spectrum. The results indicate that the growth orientations of the crystals are influenced by the hydrothermal temperature and NaOH concentration. The diameter of the nanoneedle spheres and nanoribbon spheres （40 50 μm） are almost the same as that of Ti powders. TiO 2 nanoneedle/nanoribbon sphere powders are anatase after heat treatment at 450 °C for 1 h. Furthermore, methyl orange was used as a target molecule to estimate the photocatalytic activity of the specimens. Under the same testing conditions, the photocatalytic activities of the products decrease in the following order： TiO 2 nanoneedle sphere, TiO 2 nanoribbon sphere and P25.

Preparation of TiCl4 with the Titanium Slag Containing Magnesia and Calcia in a Combined Fluidized Bed

This paper describes a new method for producing TiCl4 by chloridizing materials of high content CaO and MgO, in which a combined fluidized bed is used as a reactor to avoid agglomeration between particles caused by molten CaCl2 and MgCl2. The combined fluidized bed consists of at least a riser tube and a semi-circulating fluidized bed. Two kinds of high titanium slag, in which the total mass content of CaO and MgO is 2.03% and 9.09% respectively, are employed to examine the anti-agglomeration effect and the conversion of the materials when the temperature ranges are between 923.15K and 1073.15K, gas apparent velocity 0.7--1.1m.s-1, and inlet amount of solid materials is 4.6-7.0kg·h^-1. It is found that the anti-agglomeration effect in the combined fluidized bed is satisfactory and the new method can achieve a TiCl4 production capacity of 14.0-75.4t·m^-2·d^-1 in relation to 25.0-- 40.0t·m^-2·d^-1 from the conventional bubble bed. Furthermore, low-temperature chloridization, for example, at 923K or 973K, can also be used to produce TiCl4 and avoid agglomeration.

Preparation of titanium powders by calciothermic reduction of titanium dioxide

To develop an effective process for titanium powders production, a calciothermic reduction process of pigment titanium dioxide （w（TiO2）〉98%）, based on the preform reduction process （PRP）, was investigated by means of XRD, SEM and EDS. In this process, the mixture of TiO2 powder and CaC12 was pressed into pieces as feed preform and was reduced by calcium vapor. Titanium powders was recovered after leaching from the reduced preform with hydrochloric acid and deionized water. The results indicate when the mass ratio of CaC12 to TiO2 is about 1：4 and at a constant temperature of 1 273 K for 6 h in vacuum furnace, titanium powders with 99.55% purity by EDS analysis and irregular shape （8-15 μm in particle size） are obtained.

Preparation and Photocatalytic Properties of Magnetically Separable TiO_2 Supported on Nickel Ferrite

A magnetically separable photocatalyst TiO2/SiO2/NiFe2O4 （TSN） with a typical ferromagnetic hysteresis was prepared by a liquid catalytic phase transfer method. When the intensity of applied magnetic field weakened to zero, the remnant magnetism of the prepared photocatalyst faded to zero. The photocatalytst can be separated from water when an external magnetic field is added and redispersed into aqueous solution after the external magnetic field is eliminated, that makes the photocatalysts promising for wastewater treatment. Transmission electron microscope （TEM） and X-ray diffractometer （XRD） were used to characterize the structure of the photocatalyst indicating that the magnetic SiOffNiFe204 （SN） particle was compactly enveloped by P-25 titania and Tit2 shell was formed. The magnetic composite showed high photocatalytic activity for the degradation of methyl orange in water. A thin SiO2 layer between NiFe2O4 and TiO2 shell prevented effectively the leakage of charges from TiO2 particles to NiFe2O4, which gave rise to the increase in photocatalytic activity. Moreover, the experiment on recycled use of TSN demonstrated a good repeatability of the photocatalytic activity.

Microstructure characteristics of Ti-43Al alloy during twin-roll strip casting and heat treatment

To shorten the fabrication process of difficult-to-form TiAl sheets, twin-roll strip casting and microstructural control were investigated in Ti-43Al alloy. A crack-free sheet with dimensions of 1000 mm × 110 mm × 2 mm was obtained. The microstructure of stip casting sheets and heat treatments was systematically studied. The macrostructure consisted of columnar crystals extending inward and centrally located equiaxed crystals with severe Al segregation were observed along the thickness direction, due to the symmetrical solidification process and decreasing cooling rates. The strip casting alloy was characterized by fine duplex microstructure with a grain spacing of 20-30 μm and a lamellar spacing of 10-20 nm. Furthermore, multiple microstructures of near gamma, nearly lamellar and fully lamellar were obtained through heat treatment process with significantly improved homogeneity of the microstructure.

Hybrid functional IrO_2-TiO_2 thin film resistor prepared by atomic layer deposition for thermal inkjet printheads

IrO2-TiO2 thin films were prepared by atomic layer deposition using Ir（EtCp）（COD） and titanium isopropoxide （TTIP）. The resistivity of IrO2-TiO2 thin films can be easily controlled from 1 500 to 356.7 μΩ·cm by the IrO2 intermixing ratio from 0.55 to 0.78 in the IrO2-TiO2 thin films. The low temperature coefficient of resistance（TCR） values can be obtained by adopting IrO2-TiO2 composite thin films. Moreover, the change in the resistivity of IrO2-TiO2 thin films was below 10% even after O2 annealing process at 600 ℃. The step stress test results show that IrO2-TiO2 films have better characteristics than conventional TaN08 heater resistor. Therefore, IrO2-TiO2 composite thin films can be used as a heater resistor material in thermal inkjet printhead.

Preparation and photoelectric effect of Zn^(2+)-TiO_2 nanotube arrays

Zn 2+-TiO2 nanotube arrays were prepared by anodic oxidation method.The current-time curves were used to investigate their growth mechanism.Scanning electron microscopy and X-ray diffractometry were applied to characterizing their structures and properties.The photoelectrochemical properties were studied by electrochemical impedance spectrum(EIS).The optimised working conditions for TiO2 nanotube arrays were found to be pH 1,0.5%HF(mass fraction),20 V oxidation voltage and for 2 h.The produced sample was in anatase form,with length of 70-100 nm,thickness of 10 nm,uniform diameter and structure that does not collapse under the preparation conditions.The EIS results show that TiO2 nanotube arrays prepared with 0.5%HF(mass fraction) present a low impedance and TiO2 nanotube arrays loaded by Zn 2+could have a decreased resistance.This decrease could likely accelerate the transfer of carriers and even increase photoelectric conversion.

Preparation and Characterization of Alkaline Resistant Porous Ceramics from Potassium Titanate Whiskers

The preparation and characterization of alkaline resistant porous ceramics from potassium titanate whiskers are studied. K2Ti4O9 whiskers in the whisker preforms （mixtures of K2Ti6O13 and K2Ti4O9） were completely converted to K2Ti6O13 at 960℃. The alkaline resistance as well as the change in bending strength, porosity and permeability of the ceramics was investigated by altering the composition of the preforms in which the content of K2Ti6O13 whiskers was higher than 50% （molar fraction）. The alkaline resistance of the porous K2Ti6O13 ceramics is found much higher than that of Al2O3 in caustic NaOH solutions, and further study indicates that the K2Ti6O13 ceramics can be stably used in solutions of pH〉2.0. The bending strength increases initially with the content of the raw K2Ti6O13 in the preforms up to 66% （molar fraction） and then decreases, contrary to the behaviors of porosity and permeability. The values of bending strength, porosity and permeability of the ceramics prepared from the preform of 80% （molar fraction） raw K2Ti6O13 whiskers are respectively 56MPa, 29.4% and 330L·m^-2〈h^-1 , which are comparable to those of the porous Al2O3 ceramics.

Preparation and characterization of nanometer-sized barium titanate powder by complex-precursor method

A new complex-precursor method was proposed to prepare nanometer-sized BaTiO3 powder. Firstly,Ti2O(O2)2(ta)24-complex ions were prepared by the reaction of H2O2,Ti4+ and ta3-(ta=C6H6O6N3-) with a desirable amount of surface active agent,and then the Ba2Ti2O(O2)2(ta)2·2H2O precursor was obtained by reaction between Ti2O(O2)2(ta)24-and Ba2+. Finally,the precursor was annealed at 800 ℃ for 2 h to obtain BaTiO3 powder. The morphology,the particle size distribution,the purity and the molar ratio of Ba to Ti of BaTiO3 powder were investigated systematically by TEM,XRD,IR,Raman and chemical analysis,respectively. The results show that the BaTiO3 powders with the grain size of about 40 nm have a tetragonal crystalline structure at room temperature and a spherical morphology.

Effect of TiO_2 addition on zirconia-mullite composites fabricated by in-situ controlled crystallization of Si-Al-Zr-O amorphous bulk

Zirconia-mullite composite ceramics were fabricated by in-situ controlled crystallization of Si-Al-Zr-O amorphous bulk. The effects of TiO2 addition on the fabrication of zirconia-mullite composites were investigated. The ultra-fine zirconia-mullite composite ceramics were prepared from the amorphous bulk treated at 980 ℃ for nucleation and 1 140℃ for crystallization. The phase transformation of the ceramics was examined using differential scanning calorimetry （DSC） and X-ray diffractometry （XRD）. The microstructural features of the samples were evaluated with scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDX） and transmission electron microscopy （TEM）. The mechanical properties were also determined using Vickers indentation. The results show that the TiO2 additives with mass fraction of 1%-7% reduce the formation temperature of t-ZrO2 and mullite. When the mass fraction of TiO2 additives is less than 5%, the phases do not change, and most of TiO2 dissolves in ZrO2. When the mass fraction of TiO2 additives is over 5%, the excessive TiO2 forms a new phase, ZrTiO4. Meanwhile, the results also show that TiO2 additives have a great impact on the microstructure and mechanical properties of zirconia-mullite composites. As the TiO2 content increases from 1% to 7% （mass fraction）, the grain size and the Vickers hardness of zirconia-mullite composites increase. The composite with 3% （mass fraction） TiO2 additives attains relatively higher fracture toughness.