钛合金表面K2Ti6O13w涂层的制备及其生物活性

K2Ti6O13晶须不仅具有优越的力学性能和良好的生物学特性,而且具有与常规Ti合金相近的膨胀系数。本研究尝试选用K2Ti6O13晶须（K2Fi6O13w）作为生物活性涂层材料,利用BCC方法（混合-包埋-煅烧）在Ti合金基体上成功制备了K2Ti6O13w涂层,并对涂层的表面形态、结合强度和生物活性进行了研究。结果表明,涂层由K2Ti6O13晶须和少量的TiO2和K2Ti6O9组成,其表面粗糙多孔。由于膨胀系数的良好匹配,涂层与基体之间具有较高的结合强度,达24MPa。模拟体液培养后,涂层表面沉积了一层多孔的骨状羟基磷灰石,它由平均直径20nm,长200nm的羟基磷灰石纳米线组成,这表明钛酸钾涂层具有良好的生物活性。涂层较高的生物活性与其独特的生化特性和组分密切相关。     

钛酸钾晶须水热合成多形体TiO2及结构演变

从不同种类的钛酸钾晶须(K2Ti6O13,K2Ti4O9和K2Ti8O17)出发,通过水热条件下转晶得到了多形体TiO2晶粒,其中K2Ti6.O13晶须通过酸性条件下水热反应得到形貌规整的孪晶金红石TiO2.并借助XRI)、SEM和TEM等手段,考察了水热反应过程中的晶体结构演变,证明了前驱物中的弱结合晶面是发生晶体结构转变的关键因素,K2Ti6O13.通过{100}和{201-}晶面上的原子重排,生成孪晶金红石型TiO2.     

Ti3SiC2陶瓷材料的制备及抗烧蚀行为

以固溶少量Al的Ti3SiC2粉体为原料,采用热压烧结工艺制备出致密度大于99％的Ti3SiC2陶瓷块体材料,其硬度、抗弯强度和断裂韧度分别为775HV,520.46 MPa和7.62 MPa·m1/2.对Ti3SiC2块体在无冷却条件下进行抗氧乙炔焰烧蚀实验,结果表明:烧蚀10 s内Ti3SiC2陶瓷保持表面平整,烧蚀25 s内样品未出现宏观裂纹.SEM和XRD观察分析表明,Ti3SiC2陶瓷在高温乙炔焰和氧气的高热流冲击作用下,表面发生分解和氧化,Si和C被氧化为Si-O化物和C-O化物气体逸出,Ti元素被氧化成高温稳定的TiO2金红石相覆盖在表面;氧化层呈3层结构分布,最外层为结构疏松的TiO2,次表层则为TiO2和Al2TiO5组成的致密复合层,内氧化层为致密Al2O3富集层,Al2O3来源于固溶在原料Ti3SiC2中Al元素的氧化,并在高温下与TiO2反应生成了Al2 TiO5.具有高黏度和高熔点的Al2O3富集层可以有效阻碍O2和热流向基体的扩散,从而降低基体的氧化速率,提高Ti3SiC2材料的抗烧蚀性能.     

Mo6+掺杂TiO2纳米材料的表面性能及氧敏特性

以TiCl3为钛源, 采用溶胶-凝胶法制备Mo6+掺杂TiO2基纳米粉体,表明在400℃下低温烧结,即可得到金红石相为主晶相的TiO2基敏感材料.在低温工作条件(145℃)及1×10-4 O2下,Mo6+掺杂TiO2厚膜型气敏元件的氧敏特性比纯TiO2的好,并结合Zeta电位特性测量,其氧敏特性的增强在于表面电荷密度的提高.     

纳米K2Ti6O13W合成中的形态演化和生长机理

以纳米TiO2为原料,通过煅烧反应制备了纳米K2Ti6O13晶须,对晶须合成中温度和时间诱导的相变、形态演化和生长机理等进行了原位研究.结果表明:纳米TiO2作原料可显著降低晶须合成温度,适宜的煅烧温度为900～1100℃.形态演化观察和高温XRD分析表明:K2Ti6O13晶须的相变及生长对温度极为敏感,形态演化是基于初期爆发式的相变和随后串并联式的长大.K2Ti6O13晶须的生长遵守本研究提出的串并联机制,晶须轴向的生长台阶是串并联生长的直接结果.     

磷酸钙钛生物陶瓷膜诱导HAp沉积的研究

为了提高磷酸钙钛(CaTi4(PO4)6,简称CTP)陶瓷膜的生物活性,采用碱液对其进行了处理.研究了碱液的浓度、温度及处理时间时CTP诱导沉积HAp的影响.采用XRD、SEM检测其物相组成和表面形貌.实验结果表明:碱处理液的浓度、处理温度及时间对CTP陶瓷膜表面成分结构和诱导HAp沉积的能力有较大影响;陶瓷膜经浓度为1.0mol/L、温度为80℃的碱溶液处理2h,在仿生溶液中浸泡4d后有明显HAp沉积.说明碱处理对CTP陶瓷膜起到了生物活化改性的作用,有助于诱导HAp沉积,达到了提高生物活性的目的.     

复合半导体光催化材料ZnFe2O4-TiO2/SiO2结构与光响应性能研究

采用溶胶．凝胶法制备了负载型复合半导体光催化材料ZnFe2O4-TiO2／SiO2，并通过DTA-TG、XRD、XPS、Raman、TPR及UV-Vis DRS等实验技术对复合材料的晶体结构、表面组成及光响应性能进行了表征和评价．结果表明：ZnFe2O4晶相以高分散状态存在于光催化材料的表面；ZnFe2O4与TiO2复合可使部分Fe^3＋进入体相TiO2的晶格中，促进其由锐钛矿向金红石的相转变，同时表面剩余的少量Zn计聚集形成ZnO物相；TiO2的相变由体相开始，随着ZnFe2O4含量的增加逐渐向表面扩展；SiO2的加入使活性组分更加分散，TiO2平均粒径〈10nm；ZnFe2O4的加入明显拓宽了TiO2的吸光域，并增强了对可见光的吸收．     

Pb2+改性TiO2薄膜性能的研究

以玻璃为载体,采用溶凝胶胶法制备Pb2 -TiO2薄膜.采用AFM、XRD等技术,考察Pb2 掺杂后对TiO 2晶型结构和光催化活性的影响,结果表明,在相同制备条件下掺杂后使TiO2晶型由锐钛型向金红石型转变温度降低,经AFM分析,掺杂后使TiO2粒径增大,苯酚水溶液的光催化氧化分解反应结果表明,掺杂后TiO2的光催化活性有所提高.     

微等离子体氧化法TiO2、TiO2(W)薄膜的制备及性能

利用微等离子体氧化方法,在纯Ti金属表面制备TiO2、TiO2(W)薄膜,并用X射线衍射(XRD)、扫描电镜(SEM)初步研究了薄膜的组织结构和表面形貌.在不同的条件下,得到3种不同类型结构组成的薄膜:单一TiO2的锐钛型结构、单一TiO2金红石结构及TiO2(W)薄膜;同时对薄膜的催化特性进行了初步的研究.     

微等离子体氧化法TiO2、TiO2(W)薄膜的制备及性能

利用微等离子体氧化方法,在纯Ti金属表面制备TiO2、TiO2(W)薄膜,并用X射线衍射(XRD)、扫描电镜(SEM)初步研究了薄膜的组织结构和表面形貌.在不同的条件下,得到3种不同类型结构组成的薄膜单一TiO2的锐钛型结构、单一TiO2金红石结构及TiO2(W)薄膜;同时对薄膜的催化特性进行了初步的研究.     

Bond lengths in the ternary compounds Ti3SiC2, Ti3GeC2 and Ti2GeC

The interatomic distances in the ternary compounds Ti3SiC2, Ti3GeC2 and Ti2GeC have been determined precisely by comparing the lattice parameters of Ti3GeC2 and Ti2GeC, on the one hand, and Ti3GeC2 and Ti3SiC2, on the other. The assumptions made were that the Ti–Ge and Ti–C distances in the Ge-containing phases were identical, and that the differences in the Ti–Si and Ti–Ge distances in Ti3SiC2 and Ti3GeC2 phases were equal to the differences in the covalent radii of Si and Ge. While the results clearly show that the TiC octahedra in the ternary phases are distorted, the extent of that distortion is smaller than previously reported. The extent of the distortion was found to depend on the type of atoms surrounding the TiC6 octahedrons; the deformation is larger in the Ge-containing than in the Si-containing compounds. However, the Ti–C–Ti distances appear to be insensitive to the nature of the compound.     

Half-Metallicity and Tetragonal Deformation of Ti2RhAl,Ti2RhGa,and Ti2RhIn: A First-Principle Study

Plane-wave pseudo-potential methods based on density functional theory are used to study the electronic structures, magnetic properties, and half-metallicity of new predicted Ti₂-based full Heusler alloys Ti₂RhZ (Z = Al, Ga, In). The CuHg₂Ti-type structure is observed to be more favorable than the AlCu₂Mn-type structure for these alloys. They are half-metallic ferrimagnets with total magnetic moment of 2.00 μ _B per formula unit and follow the Slater-Pauling rule. Also, results show that these Ti₂RhZ (Z = Al, Ga, In) alloys have an indirect band gap with values of 0.577, 0.696, and 0.616 eV, respectively, in the minority spin channel. Two types of structural changes are used to test the sensitivity of half-metallicity. Moreover, the whole alloys investigated in the current work have a negative formation energy, which means they are thermodynamically stable.     

First-principles studies of typical long-period superstructures Al5Ti3, h-Al2Ti and r-Al2Ti in Al-rich TiAl alloys

First-principles calculations are performed to study the structural stabilities, electronic and elastic properties of typical long-period superstructures Al₅Ti₃, h-Al₂Ti and r-Al₂Ti in Al-rich TiAl alloys together with γ-TiAl. The obtained lattice parameters by relaxation of crystalline cells are in good agreement with the experimental data. The calculated formation enthalpies show that r-Al₂Ti has the highest structure stability from energetic point of view, and then followed by h-Al₂Ti, Al₅Ti₃ and γ-TiAl. The electronic density of states and charge density distribution indicate that due to strong hybridization between Al-2p and Ti-3d, there is a strong directional bonding between Ti and Al atoms. The elastic constants are calculated, suggesting that these structures are mechanically stable. Bulk modulus B, shear modulus G, Young’s modulus E and Poison’s ratio ν of polycrystalline materials are derived from the elastic constants. By several criteria, elastic anisotropies are analyzed, showing that these structures possess different degree of anisotropies.     

燃烧温度对燃烧合成Ti3AlC2和Ti2AlC的影响

以钛、铝和碳黑单质粉末为反应物原料,在保持Ti：Al：C=2：1：1(摩尔比)不变的情况下。分别添加具有稀释剂作用的TiC,燃烧产物主晶相由Ti2AlC2变为Ti2AlC相。随着燃烧温度的降低。Ti2AlC相的含量逐渐增多。从热力学上考虑,生成Ti2AlC2的温度上限比生成Ti2AlC的温度上限宽。当燃烧反应温度超过1600℃时,Ti2AlC难以生成,而Ti3AlC2仍可生成。     

Preparation of Ti3SiC2

Phase relations in the Ti-C-SiC system are studied with the aim of optimizing Ti₃SiC₂ synthesis. The optimal starting-mixture compositions for the synthesis of phase-pure Ti₃SiC₂ powder can be represented by the formula 3Ti + (1 ? z)C + (1 + z)SiC, where z = 0.2–0.6. In the temperature range 1630–1670 K under dynamic vacuum, the excess silicon vaporizes from the sample. The processes leading to the formation of impurity phases are discussed.     

From Ti–Al- to Ti–Al–N-sputtered 2D materials

This paper reviews thin films constituted by elements based on the Ti–Al–N system, bearing in mind the role of the condensed phases in the development of structural components and functional devices. In recent decades, the Ti–Al, Ti–N and Al–N nanocrystalline binary systems have rapidly attracted research and industry interest. These systems have revealed a great performance via atomic-level structural control, making it possible to tailor new atomic structures and morphologies suitable in different applications as protective and hard coatings and as thermal/diffusion barriers. The binary phases based on nitrogen were the first to exhibit a wealth of interesting mechanical and electrochemical behaviours. However, more recently the Ti-Al and, particularly, the Ti_{1 − x} Al _x N thin films have been applied with success in the industry. The purpose of this paper is to compile the master results concerning the production and characterisation of binary and ternary thin films of the Ti–Al–N system using similar deposition strategies. These materials form a good base to analyse the correlation between the chemical composition and the atomic structure, the preferred orientations and the morphology of 2D monolithic materials. The deposition strategies adopted and the thin films’ chemical compositions determine the as-deposited structures and, consequently, the mechanical behaviour of the thin films produced, particularly the hardness. In general, an intermediary amorphous stage is observed, i.e., the thin films exhibit a loss of crystallinity in the transition from a saturated solid solution to a new compound.     

On the mechanism of mechanochemical synthesis of Ti2SC from Ti/FeS2/C mixture

In this study, the synthesis of Ti₂SC MAX phase by high energy ball milling, and the effects of heat treatment on ball milled powder was investigated. To this aim, a mixture of Ti, FeS₂ (as sulfur source), and C according to Ti₂SC stoichiometry, were ball milled by a planetary ball mill for different milling periods up to 10 h. The structural evolution, and the morphology of the products was studied by x-ray diffraction (XRD), and scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), respectively. The results showed that after 10 h of ball milling, the raw materials reacted together and resulted in the formation of Ti₂SiC and TiC phases. The ball milled powder was then compacted and heat treated at 1000 and 1200 °C. Heat treatment caused the progressing of synthesis reactions, and led to increasing the purity of Ti₂SC phase. The heat-treated powder was leached in 1 M HCl for 2 h to remove iron from the product. The XRD results confirmed successful iron removal by leaching. SEM micrographs of the final product revealed the specific lamellar structure of MAX phases. Elemental mapping confirmed the homogeneous distribution of Ti, S and C elements.     

Fabrication of Monolithic Ti3SiC2 Ceramic Through Reactive Sintering of Ti/Si/2TiC

Fabrication of monolithic Ti₃SiC₂ has been investigated through the route of reactive sintering of Ti/Si/2TiC mixtures. Significant phase differences existed between the surface and the interior of as-synthesized products due to the evaporation of Si during the reaction process. The use of a 3Ti/SiC/C mixture as a powder bed could control the evaporation of Si and develop monolithic Ti₃SiC₂. A reaction model for the formation of Ti₃SiC₂ in the Ti/Si/2TiC system is discussed.On leave from