静电纺丝结合还原氮化法制备多孔TiN纤维及电化学研究

采用静电纺丝结合还原氮化法制备多孔TiN纤维,利用XRD、SEM、TEM和N₂吸脱附等分析其结构,采用循环伏安和充放电测试其电化学性能。结果表明,纤维为立方TiN相,纤维连续,存在较为丰富的介孔结构,其比表面积为21.55 m₂/g。电化学测试表明样品在不同扫率下的CV曲线均呈类矩形,由电流密度为20 mA/g时GCD曲线计算其比电容为24.03 F/g,在电流密度为50 mA/g时经4500次充放电循环后样品的比容量仍能保持90 %以上,当功率密度为0.02 kW/kg时样品的能量密度为3.3 Wh/kg。因此,采用本方法制备的多孔TiN纤维在超级电容器领域具有应用潜力。     

铝热还原氮化法制备TiN-Al2O3复合粉体

本文用Al作还原剂还原氮化TiO2制备了TiN—Al2O3复合粉体。通过对比不同温度下的含氮率和理论含氮率，可以判断反应进行的程度；通过XRD分析研究不同温度下的相变化；通过SEM、EDS分析观察晶粒的形貌和成分。研究结果发现，TiN在1100℃开始生成，1450℃TiN生成反应结束。SEM照片显示细小、不规则的TiN晶粒和多面体Al2O3晶粒相互交叉均匀分布，Al2O3晶粒尺寸10μm左右，TiN晶粒尺寸2μa左右。表明用此方法可以在比较低的温度下合成颗粒细小分散均匀的TiN-Al2O3复合粉体。     

热处理对超级电容器MnO2电极电化学性能的影响

采用阳极电沉积法制备MnO2粉末,并在不同温度(200～450℃)下对MnO2热处理,通过XRD分析热处理温度对MnO2粉末物相结构的影响,采用循环伏安法、恒流充放电法测试热处理温度对MnO2电极电化学性能的影响。结果表明:随着温度的升高,MnO2由原始的γ-MnO2逐渐变为β-MnO2,MnO2电极的比容量先增加后减小;当温度为300℃时,MnO2电极的比容量达到最高,在0.5 mol/L Na2SO4溶液中循环伏安扫描速度为10 mV.s-1条件下,电极比容量为156 F.g-1,且此时电极的稳定性良好,在10000个循环充放电内MnO2电极比容量几乎无衰减。     

电化学还原TiO2制备金属钛及反应过程的研究

采用熔盐电解法,在900℃熔盐CaCl2中以烧结TiO2为阴极,石墨棒为阳极制备出了金属钛.研究了不同温度下烧结阴极的形貌及其对电解反应的影响.结果表明：600℃下烧结4 h的阴极具有良好电化学反应性能;电解过程中脱氧速度不均匀;TiO2电极的还原是由外向内,由高价向低价再到金属分步进行的;电解还原过程电流效率低约为15%.阴极的孔隙大小和颗粒尺寸会影响电极的反应速度.     

LiF-NaF-KF-K_2TiF_6熔盐中Ti(IV)的电化学还原及电结晶过程

采用循环伏安法和计时电流法研究了700℃时LiF-NaF-KF-K2TiF6熔盐中Ti(IV)在铂电极上阴极电化学还原机理以及电结晶过程。结果表明:Ti(IV)的电化学还原机理为三步骤电荷传递反应:Ti(IV)+e→Ti(III);Ti(III)+2e→Ti(I);Ti(I)+e→Ti(0),且阴极过程可逆;电结晶过程为瞬时形核。     

介孔材料的发展及合成机理

美国Mobil公司的研究人员在1992年制成了M41S硅基系列,引起了国际物理学、化学及材料科学界的高度重视,人们对这种有机与无机离子在分子水平的自组装结合方式产生了浓厚兴趣.为了进一步探讨有关介孔结构形成的本质,近10年来介孔结构形成机理一直成为研究的焦点,人们提出了各种的形成机理来解释这种规则排布的介孔结构的形成过程.本文简述了介孔材料的发展,介绍了介孔材料的合成机理.     

模板剂对介孔二氧化钛孔结构和光催化性能的影响(英文)

钛酸丁酯作为前驱体,Span80、Span85和TritonX-114作为模板剂合成介孔二氧化钛,以氮吸脱附方法表征材料织构特性,以光催化丙酮研究材料孔结构对光催化性能的影响。结果表明,模板剂用量和种类对孔结构和光催化性能有较大的影响。直通孔道结构的二氧化钛比狭缝或墨水瓶孔道的二氧化钛具有更好的光催化活性,大的比表面积和孔径也有利于光活性的提高。     

碳包覆氧化镍纳米颗粒制备与电化学性能研究

采用直流电弧放电等离子体技术制备了核壳结构碳包覆氧化镍纳米颗粒,并采用X射线衍射、高分辨透射电子显微镜、X射线能量色散分析谱仪和表面物理吸附仪等测试技术对样品的微观结构进行研究。并利用循环伏安法、恒电流充放电以及交流阻抗等技术研究其作为超级电容器电极材料的电化学性能。结果表明:直流电弧等离子体技术制备的碳包覆氧化镍纳米颗粒具有典型的核壳结构,内核为面心立方结构的氧化镍纳米颗粒,外壳为碳层。颗粒形貌主要为立方体结构,粒度均匀,分散性良好,粒径分布在30～70 nm范围,平均粒径为50 nm,外壳碳层的厚度为5 nm。碳包覆氧化镍纳米颗粒具有较高的比容量和良好的电化学活性。     

介孔CeO2的化学沉淀法合成及表征

以硝酸铈(Ce(NO3)3.6H2O)、碳酸铵((NH4)2CO3.H2O)为原料,十六烷基三甲基溴化铵(CTAB)为模板剂,采用化学沉淀法合成了一系列具有不同孔径的介孔CeO2粉末,使用X射线衍射(XRD)、差示/热重(DSC/TG)、BET孔性能测试、透射电镜(TEM)及红外光谱(IR)分析等手段对合成产物进行了分析和表征,探讨了CTAB与Ce的摩尔比、反应温度、焙烧温度和时间对孔径大小和比表面积的影响。在CTAB与Ce的摩尔比为1∶1、反应温度为80℃、焙烧温度为300℃、焙烧时间为1 h条件下,制得了比表面积为132 m2/g的介孔CeO2。     

电泳沉积耦合电化学还原法制备柔性石墨烯自支撑薄膜电极超级电容器(英文)

通过电泳沉积和电化学还原相耦合的方法制备柔性的石墨烯自支撑薄膜电极。首先,通过电沉积的方法在石墨基底上制备氧化石墨烯薄膜,然后通过对氧化石墨烯薄膜进行电化学还原,得到电容性能优异的石墨烯薄膜电极材料。通过SEM、XRD、FT-IR和电化学测试对石墨烯的表面形貌、结构和电容性能进行表征。结果表明:制备的石墨烯电容性能良好,在1 mol/L的硫酸电解液中,循环伏安扫速为10 mV/s时,比电容为254 F/g;当电流密度为83.3 A/g时,比电容能保持在132 F/g;最大功率密度可达39.1 kW/kg,能量密度为11.8 W·h/kg;充放电循环1000次后,电容能保持97.02%,表明该石墨烯薄膜电极材料具有优异的循环稳定性能。     

Electrochemical Nucleation of Titanium on Platinum

ＥｌｅｃｔｒｏｃｈｅｍｉｃａｌＮｕｃｌｅａｔｉｏｎｏｆＴｉｔａｎｉｕｍｏｎＰｌａｔｉｎｕｍＺｈａｏＢａｏｄｏｎｇ（赵保东）ＢｒａｎｃｈＣａｍｐｕｓｏｆＢｅｉｊｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１０００８３，ＣｈｉｎａＲｅｃｅｉｖｅｄ１７Ｆｅｂ...     

溶剂热合成纳米氮化钛粉体的研究

将质量比为1：4的TiCl4和NaN。放入不锈钢反应釜内，以二甲苯为溶剂，填充率为60％，用溶剂热方法，在温度340℃，保温24h，制得粉体。粉体分别经二甲苯，无水乙醇、蒸馏水洗涤，105℃干燥和直接经700℃煅烧2h，XRD测试表明：制备出的氮化钛粉体为纳米立方相粉体，晶格常数a=0．4241nm，平均粒径为11．04nm，700℃煅烧后全部转化为TiO2和Ti的混合物；IR测试表明在619cm^-1的吸收峰归属为Ti—N键，表面吸附了一些有机溶剂，有C=C弯曲振动峰；SEM测试表明其晶粒有立方状、圆粒状，长柱状和内部有中孔的圆环状晶粒，表面存在毛绒状的细小晶须，形成网状包裹在晶粒表面。     

Gas-Phase Production of Titanium Nitride and Carbide Powders

The Bureau of Mines investigated a procedure to produce fine-sized titanium nitride, carbide, and carbonitride powders. These powders, because of their high hardness and abrasion resistance, can be substituted for tungsten carbide in some cutting tool applications. Titanium nitride and carbide powders can be cemented together with nickel. The investigated approach produces titanium nitride by reducing titanium tetrachloride with magnesium or sodium vapor in a nitrogen atmosphere at temperatures between 750 and 1,050°C (1,382 and 1,922°F). Titanium carbide and titanium carbonitride can be formed by adding methane to the nitrogen atmosphere. Titanium tetrachloride reduction efficiencies as high as 98% are achieved. X-ray diffraction analyses showed that the powders contain no major impurities. Because the reactions occur in the gas phase, powders finer than 1 μm are produced.     

氮化钛涂层刀具的镀制及应用

扼要介绍空心阳极真空离子镀膜技术的原理,具体分析利用DKYL-1000型真空离子镀膜机进行TiN镀制的几个主要工艺参数,并对利用该设备镀制的刀具在生产上的应用情况作了总结。     

氮化硅陶瓷刀具表面涂覆高硬耐磨氮化钛涂层研究

用高能量密度脉冲等离子体于室温下在氮化硅陶瓷刀具上成功沉积了高硬耐磨的氮化钛涂层。薄膜厚度用光学显微镜和俄歇电子能谱仪测定，薄膜元素和相组成与分布分别用俄歇电子能谱仪、X光电子能谱以及X光衍射仪测定，薄膜微观结构用扫描电镜观察，薄膜表面粗糙度用光学显微镜测定，薄膜力学性能由纳米压痕实验和纳米划痕实验确定，薄膜的磨损性能用上业条件下的切削实验评价。实验结果表明，在最优化条件下，涂层与基体的结合力很好，纳米划痕实验临界载荷达80mN以上；氮化钛涂层具有很高的硬度和杨氏模量，分别达28GPa和350GPa以上。涂层刀具用于HB达2200MPa—2300MPa的HT250钢切削实验表明，刀具耐磨损能力增强，寿命明显提高。     

Electrochemical behavior of the Ti6Al4V alloy implanted by nitrogen PIII

Plasma surface treatments have been used very often to enhance the surface properties of metallic materials. In this work, Ti6Al4V titanium alloy was treated by nitrogen plasma immersion ion implantation (NPIII) in order to obtain improvements in its surface properties, such as corrosion resistance evaluated here. The microstructure and corrosion behavior of the implanted and unimplanted samples were evaluated, using, XRD, GDOES and potentiodynamic polarization and impedance electrochemical spectroscopy tests in 0.6 M NaCl solution. It was verified that the NPIII created resistant layers to corrosive attacks. In corrosion tests by polarization, the implanted samples showed corrosion current density reduction of about 10 times compared to the Ti6Al4V alloy without treatment. Besides that, it was also observed a reduction of the passive current density of one order of the magnitude. In all the studied cases, the polarization curves were shifted to more positive values of potentials, indicating a lower tendency of these PIII treated surfaces to corrosion. The implantation process produced a thin TiN surface layer followed by Ti₂N and then a layer with nitrogen in solid solution, all detected by GDOES combined with X-ray diffraction. These layers promoted an excellent polarization resistance of the Ti6Al4V surfaces on impedance spectroscopy tests also. This better performance in these tests can be correlated with the formation of continuous nitride layer, which could retard chloride ions ingress into the substrate.     

Comparison of electrochemical porosity test methods for TiN-coated stainless steel

Porosity is virtually unavoidable in thin coatings deposited on metal surfaces. This work compares various electrochemical porosity test techniques for TiN-coated stainless steels. The corrosivity of test process, which represents the degree of corrosion of stainless steel after a particular electrochemical test process, is used as the basis for comparison. Three electrochemical techniques are examined for porosity measurement in H₂SO₄ solutions containing KSCN: the anodic current ratio, a coulometric method and a porosity calculation from E_corr and R_p measurement. The common characteristic of test results is that porosity indexes obtained by various methods decrease with decreasing corrosivity of the test process_, and approach constant values. These constant values of porosity indexes, which are obtained at test conditions that cause little damage to TiN coatings, are close to each other and should represent the accurate porosity value of this TiN-coated sample. This work reveals that different electrochemical porosity test techniques can achieve a similar result for porosity measurements on TiN-coated stainless steels.     

Inducing Macrophages M2 Polarization by Dexamethasone Laden Mesoporous Silica Nanoparticles from Titanium Implant Surface for Enhanced Osteogenesis

The study conveys an idea to enhance the osseointegration of titanium implant(Ti) through modulating macrophages M2 polarization. The ～ 100 nm spherical mesoporous silica nanoparticles(MSN) that compromised of ～ 4-nm-diameter nanotunnels were synthesized by the conventional sol–gel method, into which the dexamethasone(DEX) was loaded(DEX@MSN). The DEX@MSN could consistently release DEX and showed favorable cytocompatibility in RAW264.7 cells. The arginase-1 expression, a specific marker for macrophages M2 polarization, was also enhanced by DEX@MSN treatment. Then, the Ti was pre-treated with anodization under 5 V to generate the titania nanotubes with ～ 30 nm diameter(NT-30) and the DEX@MSN was introduced onto NT-30 surface via electrophoretic deposition, with the aid of chitosan. After optimizing the deposition parameters, the supernatants of RAW264.7 from the decorated implant surface could significantly promote the osteogenic differentiation of murine primary bone marrow mesenchymal stem cells. These findings demonstrate that delivery of DEX from implant surface can modulate the macrophages M2 polarization and result in favorable osteogenesis.     

钛合金表面微弧氧化／水热处理复合陶瓷层的性能研究

对微弧氧化后的Ti6Al4V合金表面进行了水热处理,对处理后涂层的成分、形貌及其在Hank's模拟体液中的腐蚀性能进行了研究.试验结果表明:水热处理后,微弧氧化层中以无定形态钙磷酸盐存在的Ca、P元素转化为针状羟基磷灰石,厚度约为5μm,并在微弧氧化膜微孔边缘和底部优先生长.与微弧氧化层相比,水热处理后涂层的粗糙度明显下降,同时显微硬度下降约1/3.电化学腐蚀试验表明:微弧氧化显著改善了钛合金在模拟体液中的耐腐蚀性能;水热处理钛合金自腐蚀电位低于纯钛合金,但当处于人体电位0.4～0.6V(vs.SCE)范围时,微弧氧化/水热处理钛合金的腐蚀电流比纯钛合金低1个数量级.     

W、Mo离子注入对离子镀TiN薄膜表面结构和性能的影响

目的进一步改善氮化钛薄膜的摩擦学性能。方法利用金属蒸汽真空弧源(MEVVA)在离子镀TiN薄膜表面进行等剂量W、Mo离子注入。采用扫描俄歇系统、光学三维形貌仪、X射线衍射仪和纳米压痕仪,分别分析了TiN薄膜的离子注入深度、表面形貌及粗糙度、相结构和不同压入深度的薄膜硬度。在球盘滑动摩擦磨损试验机上考察了TiN薄膜的摩擦学性能,并利用扫描电子显微镜和三维形貌仪对其磨损形貌进行分析。结果等剂量离子注入后,TiN表面注入层中W离子的含量明显大于Mo离子,两种离子注入对TiN薄膜的表面形貌和硬度的影响较小。XRD结果表明,W离子和Mo离子注入后均发现了Ti_2N硬质相。两种离子注入均可以不同程度地降低TiN薄膜的摩擦系数和磨损率。结论 W、Mo离子注入均可显著改善TiN薄膜的摩擦学性能,但Mo离子更有利于其摩擦系数的降低,而W离子注入更有利于TiN薄膜磨损率的降低。