镁合金微弧氧化绿色陶瓷膜的制备

为了开发更多颜色的微弧氧化陶瓷膜层,通过试验在AZ91D镁合金表面制备出了绿色陶瓷膜层,分别研究了着色盐K2Cr2O7添加量为0.2,0.4,0.6,0.8,1.0,1.2,1.4g/L时和微弧氧化时间为5,10,20,30,40 min时对陶瓷膜的影响规律.结果表明:在10 g/L NaAlO2、1 g/L K2Cr2O7、少量NaOH和H2O2的电解液中进行微弧氧化着色反应,可以得到颜色均匀、致密性较好的绿色陶瓷膜层;陶瓷膜颜色的深浅可以通过微孤氧化时间来控制,微弧氧化时间越长,所得到的膜层颜色越深.绿色氧化膜的成分主要由MgO、Al2O3和MgCr2O4组成,其中MgCr2O4是使膜层产生颜色的物质.     

氧化处理时间对Ti6Al4V微弧氧化陶瓷膜的影响

采用交流微弧氧化法于：Na：SiO3-KOH-(NaPO3)6溶液中在％6A14V表面形成了氧化物陶瓷膜．利用扫描电镜、电子探针及X射线衍射研究了陶瓷膜的组织形貌、元素的分布和相组成．研究表明：在恒定的微弧氧化电参数(U =500V,U-=100V和f=600Hz)下,随氧化时间延长,电流密度逐渐降低,膜层厚度不断增加;相对致密均匀的膜分为3层：过渡层、致密层与疏松层．膜层主要由TiO2(锐钛矿和金红石)相组成,延长处理时间,锐钛矿相及金红石相的相对含量发生变化,金红石相TiO2逐渐增多,而锐钛矿相TiO2减小．膜层相的形成过程可分为两个阶段。     

不同基体材料微弧氧化生成陶瓷膜的研究

1　前　言微弧氧化是一种表面处理新技术[1～ 2 ] ,它直接在Ａｌ、Ｍｇ和Ｔｉ等金属表面原位生长的致密陶瓷氧化层 ,可改善材料自身的防蚀、耐磨和电绝缘的特性。陶瓷氧化膜的厚度可通过工艺条件加以调整 ,可达 30 0 μｍ ,最高显微硬度达ＨＶ 2 5 0 0 ,绝缘电阻大于10 0ＭΩ ,与基体的结合力强 ,工件尺寸变化小。陶瓷材料以其特有的绝缘性、高硬度、高强度、耐磨、耐磨蚀、耐高温等优异性能成为继钢铁、铝材以后的第三代工程材料。但由传统烧结工艺制备的陶瓷材料脆性较大 ,可加工性差 ,一直束缚其广泛应用。而微弧氧化技术能在加工成形的…     

黑色微弧氧化陶瓷膜的制备及其性能研究

用微弧氧化的方法在LYl2铝合金基体上获得黑色陶瓷膜,分别研究了添加剂浓度对陶瓷膜的成膜速度、表面粗糙度、硬度和耐磨性的影响。结果表明：所采用的添加剂浓度增大,陶瓷膜的黑度加深;在其浓度较低条件下,陶瓷膜显微硬度几乎保持不变,成膜速度、表面粗糙度和耐磨性等性能均得到一定程度的改善;其浓度过高时,陶瓷膜显微硬度、耐磨性和成膜速度均会下降,表面粗糙度却增大,陶瓷膜性能逐渐恶化。实验证明,当添加剂浓度为5g／L时,黑色微弧氧化膜表现了优异的综合性能。     

TC4钛合金微弧氧化因素对生物陶瓷膜中Ca,P相对含量的影响

为了提高钛合金陶瓷膜的生物相容性,采用微弧氧化技术在TC4钛合金表面制备了一层富含Ca,P的生物活性陶瓷膜。采用SEM,EDS,XRD研究了电流密度、溶液中Ca,P摩尔比、添加剂EDTA.2Na浓度对膜层中Ca,P相对含量(原子分数)及Ca,P摩尔比的影响及微弧氧化生物陶瓷膜层的形貌及组成。结果表明:随着电流密度的增大,膜层中的Ca,P相对含量增加,Ca,P摩尔比也逐渐增加;增大溶液中Ca,P摩尔比,膜层中Ca相对含量有所增加,Ca,P摩尔比也逐渐增加;当加入添加剂EDTA.2Na时,膜层中的Ca相对含量显著增加,从而使膜层中Ca,P摩尔比显著增加;氧化膜由致密的内膜层和多孔的外膜层构成,主要由Ca,P,O,Ti,V元素组成,其相成分主要为金红石和板钛矿型TiO2,并含有一定量的非晶相Ca,P化合物。     

工艺条件对镁合金微弧氧化的影响

在含有Na2SiO3、NaF、甘油及KOH的电解液中以恒电流方式对AZ31B镁合金进行微弧氧化处理,研究了电解液组分、浓度、电流密度及氧化处理时间等对微弧氧化过程及膜层性能的影响．研究表明：随着电解质浓度的增加,起火时间、起火电压基本呈下降趋势,氧化膜厚度呈增长趋势;过量的NaF会抑制放电;甘油的存在可稳定电解液,抑制尖端放电,使膜层的厚度降低;电流密度的增加可以降低起火时间,增加氧化膜的厚度,对放电电压没有明显影响;随着氧化处理时间的延长,氧化膜的厚度不断增长．     

铝合金微弧氧化着色处理

研究了LY12铝合金微弧氧化陶瓷膜的着色技术,分析了各种参数对膜层色度的影响以及实验过程中所出现的问题以及解决方法,并通过用不同的电解液和添加剂而获得了色彩不同的膜层.     

电弧喷涂铝层的微弧氧化

介绍了在低碳钢表面进行电弧喷涂层，然后采用微弧氧化获得陶瓷膜的方法。分析了不同喷涂工艺参数的电弧喷涂铝层的微弧氧化，观察了复合膜层的断面形貌，进行了X－射线衍射分析，并研究了陶瓷层厚度随电流密度和强度时间的变化情况。     

TA2工业纯Ti微弧氧化陶瓷膜生长规律及电容效应

对TA2工业纯Ti微弧氧化陶瓷膜的生长规律进行了实验研究,分析了陶瓷膜表面形貌、厚度、相结构等不同生长阶段的实验现象及结果。模拟微弧氧化工艺反应过程,运用多种理论建立并分析了氧化陶瓷膜生长模型及等效电路。模型及电路分析结果证明,陶瓷膜在形成时呈现先离散分布后连接成片的生长特点,成膜后TiO2陶瓷膜具有交流耦合电容效应。模型及等效电路分析与实验结果是吻合的,为改善TA2工业纯Ti微弧氧化工艺并提高陶瓷膜性能提供了实验与理论基础。     

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。     

K2Ti6O13 Nanoparticle-Loaded Porous rGO Crumples for Supercapacitors

One-dimensional alkali metal titanates containing potassium,sodium,and lithium are of great concern owing to their high ion mobility and high specific surface area.When those titanates are combined with conductive materials such as graphene,carbon nanotube,and carbon nanofiber,they are able to be employed as efficient electrode materials for supercapacitors.Potassium hexa-titanate(K2Ti6O13,KTO),in particular,has shown superior electrochemical properties compared to other alkali metal titanates because of their large lattice parameters induced by the large radius of potassium ions.Here,we present porous rGO crumples(PGC)decorated with KTO nanoparticles(NPs)for application to supercapacitors.The KTO NP/PGC composites were synthesized by aerosol spray pyrolysis and post-heat treatment.KTO NPs less than 10 nm in diameter were loaded onto PGCs ranging from 3 to 5μm.Enhanced porous structure of the composites was obtained by the activation of rGO by adding an excessive amount of KOH to the composites.The KTO NP/PGC composite electrodes fabricated at the GO/KOH/TiO2 ratio of 1:3:0.25 showed the highest performance(275 F g−1)in capacitance with different KOH concentrations and cycling stability(83%)after 2000 cycles at a current density of 1 A g−1.     

Interfacial reactions in K2Ti6O13(w)/Al2O3/Al composite

Abstract

A pure Al matrix composite, reinforced by potassium titanate whiskers coated with sol–gel alumina, was fabricated by squeeze casting. Good interface bonding was achieved in the coated composite. Interfacial reactions in the composite were found to be less severe than those in an uncoated composite, owing to the barrier effect of sol–gel -Al₂O₃ coating. After the composite was thermally exposed at 530°C for 30 h, the alumina coating still restrained the decomposition of the whisker structure, and thus prevented a decrease in the strength of the composite. However, after a thermal exposure at 700°C for 10 h, the coating was no longer held on whisker surfaces. Mechanical testing showed that tensile fracturing of the coated composite tended to occur at the coating/matrix interface where the interfacial bonding is weaker than at the coating/whisker interface.     

Molten salt synthesis of single-crystalline K2Ti6O13 annular nanostructures

Single-crystalline K2Ti6O13 ring-like structures have been synthesized via a simple molten salt method without any templates and surfactants. The annular structures have several different types, such as nanoring, wheel-like and diskette-like ring. Each type of rings was characterized individually by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). These annular structures are formed by the loop-by-loop self-coiling of K2Ti6O13 nanobelts in the ring plane. The driving force of self-coiling is suggested to minimize the local electrostatic energy introduced by spontaneous polarization.     

Environmentally friendly growth of single-crystalline K2Ti6O13 nanoribbons from KCl flux

Single-crystalline K₂Ti₆O₁₃ nanoribbons with typical width ranging from one hundred nanometers to a few hundred nanometers and length up to tens of microns were prepared from KCl flux. The nanoribbons were characterized by a range of methods including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, selected area electron diffraction and high-resolution transmission electron microscopy. Ultraviolet–visible experiments showed that the K₂Ti₆O₁₃ nanoribbons were wide-band semiconductors with a band width E_g = 3.4 eV. The mechanism of one-dimensional growth of the nanoribbons was attributed to the oriented attachment mechanism.     

水热法制备BaO-Nd_2O_3-TiO_2系纳米粉体

采用水热法制备了BaO-Nd2O3-TiO2(BNT)系纳米粉体。在KOH碱性溶液中,以TiCl4,BaCl2和Nd(NO3)3为反应物,先制备出BaO-Nd2O3-TiO2(BNT)凝胶前驱体,再经低温水热处理,得到BNT系纳米粉体。产物通过XRD、IR、TEM等手段进行测试分析,结果表明:该法获得的BNT系纳米粉体为立方相结构,稀土元素掺杂均匀,产物粒径小,分散度高。讨论了BNT系纳米粉体的形成机理,发现凝胶前驱体的存在有利于BNT系纳米粉体的成功制备。     

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.