医用NiTi合金表面溶胶-凝胶法制备TiO2-SiO2薄膜

采用溶胶－凝胶法在ＮｉＴｉ形状记忆合金表面制备了ＴｉＯ_２－ＳｉＯ_２复合薄膜,在提高医用ＮｉＴｉ合金的抗腐蚀性方面,收到了显著的效果．运用电化学方法对不同组成的ＴｉＯ_２－ＳｉＯ_２薄膜在模拟体液中的腐蚀行为进行了研究,结果表明,随薄膜中 Ｔｉ／Ｓｉ比的增加,ＴｉＯ_２－ＳｉＯ_２薄膜的抗腐蚀性增强．划痕试验表明 ＴｉＯ_２－ＳｉＯ_２（Ｔｉ／Ｓｉ＝４：１）膜与ＮｉＴｉ合金基体具有较高的界面结合强度．用原子力显微镜（ＡＦＭ）对ＴｉＯ_２－ＳｉＯ_２薄膜的表面形貌及表面粗糙度进行观察和分析,解释并讨论了ＴｉＯ_２－ＳｉＯ_２薄膜的配方组成与其抗腐蚀性的关系,ＳｉＯ_２含量较少时,薄膜结构致密,膜层均匀平滑,且膜基结合力好,作为医用ＮｉＴｉ合金的表面保护层,可以使其耐腐蚀性有显著提高．     

Al-Ti-TiO2体系燃烧合成及其反应过程研究

利用Ａｌ－Ｔｉ－ＴｉＯ_２体系放热反应,采用自蔓延高温合成工艺。原位合成了ＴｉＡｌ基体和Ａｌ_２Ｏ_３颗粒,成功制备出ＴｉＡｌ／Ａｌ_２Ｏ_３复合材料．结合差热分析,通过对不同温度下反应产物相组成分析;对Ａｌ－Ｔｉ－ＴｉＯ_２体系燃烧反应过程进行了初步研究．结果表明,铝热还原反应是一个分步过程,先期发生的Ａｌ－Ｔｉ、Ｔｉ－ＴｉＯ_２反应降低了Ａｌ－ＴｉＯ_２还原反应的起始温度．     

原位生成TiC/Ti5Si3纳米复合材料的显微结构研究

研究了原位生成ＴｉＣ／Ｔｉ_５Ｓｉ_３纳米复合材料的显微结构．实验结果表明,以ＳｉＣ和Ｔｉ 为原料,通过反应热压工艺可以原位合成ＴｉＣ／Ｔｉ_５Ｓｉ_３复合材料,其中的大部分ＴｉＣ粒子为纳 米粒子．ＴｉＣ晶粒与Ｔｉ_５Ｓｉ_３晶粒的晶界上存在原子台阶．复合材料还含有少量Ｔｉ_３ＳｉＣ_２相．这 些Ｔｉ_３ＳｉＣ_２相主要呈棒状分布在Ｔｉ_５Ｓｉ_３基体中,另有少量Ｔｉ_３ＳｉＣ_２相位于大的ＴｉＣ晶粒内．     

2219铝合金搅拌摩擦焊接头微观组织对微弧氧化膜生长的影响

采用微弧氧化方法在硅酸盐电解液里在2219铝合金搅拌摩擦焊接头表面均匀生长一层50 μm陶瓷膜, 分析了铝合金基体和焊缝区陶瓷膜的形貌、相组成和显微硬度分布, 探讨了合金显微组织和微弧氧化膜生长过程的相互影响. 结果表明, 铝合金显微组织对微弧氧化膜的生长影响较小, 铝合金基体和焊缝区的微弧氧化膜特性几乎相同, 陶瓷膜都是由α-Al₂O₃、γ-Al₂O₃和莫来石(3Al₂O₃·2SiO₂)相组成; 不同区域膜层的显微硬度相等, 其平均硬度约为HV 1500. 另外, 微弧放电高温过程对膜/基界面附近的铝合金显微组织没有影响.     

50Ti/HA生物材料的组织结构与体外生物活性

通过热压烧结的方法制备出５０Ｔｉ／ＨＡ生物复合材料,对其组织结构及其在模拟体液中的生物活性进行了研究．ＸＲＤ结果表明,在１２００℃烧结时,原始材料中的Ｔｉ与ＨＡ之间发生了复杂的化学反应,反应产物为Ｔｉ_２Ｏ、ＣａＴｉＯ_３、ＣａＯ以及一种类ＴｉＰ相．将复合材料浸入模拟体液一天后,其表面就形成一层连续的磷灰石膜,随着浸泡时间的延长,磷灰石膜逐渐增厚．这种膜沿［００１］方向具有明显的择优取向,其形成主要与复合材料中生成的Ｔｉ_２Ｏ有关．     

以正钛酸为原料制备纳米TiO2光催化剂

以正钛酸为原料,通过直接水解法制备纳米ＴｉＯ_２;并对样品分别进行了差热分析、Ｘ射线衍射分析和透射电子显微镜分析．结果表明,样品粒子为混晶型纳米ＴｉＯ_２,单分散性良好,粒径分布范围狭窄．当它应用于阴离子表面活性剂十二烷基苯磺酸钠的光催化降解时,与Ｐ－２５光催化剂相比,具有较好的催化活性．同时,我们用Ａｌ_２Ｏ_３陶瓷膜回收纳米ＴｉＯ_２循环再利用;这为纳米ＴｉＯ_２在环保方面的大规模应用创造了条件．     

热分解氧化反应对TiO2电容压敏电阻器性能的影响

研究了具有热分解氧化反应的ＣｕＯ、ＭｎＯ_２等的一类氧化物对ＴｉＯ_２压敏电阻器性能的影响,采用Ｃ—Ｖ分析、Ｉ—Ｖ测量和介电测量等实验手段,分析了它们的作用机理．结果发现,在晶界处发生的热分解氧化反应能增加界面态密度,提高晶界势垒高度,从而改善ＴｉＯ_２电容压敏电阻器的非线性性能．     

La2O3在MgO-Al2O3-SiO2-TiO2微晶玻璃中的作用

在ＭｇＯ－Ａｌ_２Ｏ_３－ＳｉＯ_２－ＴｉＯ_２玻璃中添加不同数量的氧化镧,采用差热分析、Ｘ射线衍射及电子显微镜等技术研究了氧化镧对玻璃析晶过程与力学性能的影响．氧化镧的加入使玻璃中析出α－堇青石相的温度降低;同时避免了高膨胀方石英相的析出．随着氧化镧加入量的增加,玻璃整体析晶能力下降,微晶玻璃中晶相含量减少,晶粒尺寸增大,微晶玻璃的弹性模量与硬度减小,断裂韧性增加,体现出大尺寸长柱状金红石晶粒的增韧作用．     

Na0.5Bi0.5TiO3-BaTiO3陶瓷的介电和压电性能研究

研究了Ｎａ_０．５Ｂｉ_０．５ＴｉＯ_３和（Ｎａ_０．５Ｂｉ_０．５）_０．９４Ｂａ_０．０６ＴｉＯ_３陶瓷的电滞回线、压电性能和热滞现象·得到（Ｎａ_０．５Ｂｉ_０．５）_０．９４Ｂａ_０．０６ＴｉＯ_３陶瓷的剩余极化Ｐ_ｒ＝１９ｕＣ／ｃｍ^２、矫顽场Ｅ_ｃ＝４．７ｋＶ／ｍｍ．发现用适量的Ｂａ^２＋取代（Ｎａ_０．５Ｂｉ_０．５）^２＋尽管压电性能有所提高,但同时使得材料的温度稳定性大大降低．     

聚乙烯醇(PVA)对无支撑氧化铝膜微观结构的影响

聚乙烯醇（ＰＶＡ）能够避免溶胶－凝胶法制备的Ａｌ_２Ｏ_３膜在干燥阶段产生微裂纹,同时也对Ａｌ_２Ｏ_３膜的微观结构产生影响．利用ＸＲＤ、ＤＴＡ、ＴＧＡ、ＦＴ－ＩＲ及Ｎ_２吸附等手段研究掺杂ＰＶＡ对Ａｌ_２Ｏ_３膜的物相组成、热稳定性以及比表面积、孔径分布、孔表面分形性等微观结构的影响．研究表明,经过４００℃煅烧ＰＶＡ完全排除．与纯Ａｌ_２Ｏ_３膜相比,添加ＰＶＡ的Ａｌ_２Ｏ_３膜吸附量较大,比表面积有所增大,但并不随着ＰＶＡ含量的增多而增加．ＰＶＡ有利于 Ａｌ_２Ｏ_３膜孔径的调整,使孔径分布更狭窄,孔体积也有较大程度的增加．随着 ＰＶＡ的加入,Ａｌ_２Ｏ_３膜的孔表面分形维数降低．     

纯钛表面微弧氧化膜纳米压入法研究

微弧氧化是一项较新的等离子体化学-电化学成膜技术，硬度和弹性模量是膜的基本微区力学性能。采用交流微弧氧化方法的铝酸盐溶液中在TA2纯钛表面制备出较厚的氧化膜，利用纳米压入法测定了膜的硬度和弹性膜量，并探讨了微弧放电对氧化膜相组成和性能的影响。研究结果表明：膜的显微硬度和弹性模量分布有相似的变化规律，从膜表层到膜内部，硬度和弹性模量逐渐增加，并在内层膜达到最大值，分别为9.78GPa和176GPa，比钛基体高的多；膜不同浓度处TiO2金红石和TiAl2O5相的相对含量变化决定了硬度和弹性模量的分布。     

微弧氧化处理对钛铌合金力学及摩擦磨损性能的影响

采用微弧氧化的方法于磷酸盐电解液中在二元β型TiNbx(x=5,10,15,20,25)合金表面制备了微弧氧化涂层。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)表征各合金表面微弧氧化涂层的物相组成和微观形貌。采用纳米压痕仪、球-盘摩擦磨损实验仪分析了微弧氧化处理对钛铌合金力学性能、耐磨性的影响。结果表明,通过微弧氧化处理可以有效的在各基体表面制备出氧化涂层,表面微孔数目及大小无明显差别,拥有相似的致密度,氧化涂层主要由TiO₂相组成。随着基体Nb含量的增加,各基体表面微弧氧化涂层的硬度值与弹性模量表现出相同的变化趋势,Ti-15Nb合金表面微弧氧化涂层的硬度值和弹性模量值最大。经过微弧氧化处理后,Ti-5Nb和Ti-15Nb表面摩擦系数与基体相近,并无减摩效果;Ti-10Nb、Ti-20Nb和Ti-25Nb表面摩擦系数下降了55%以上,主要磨损机制由磨粒磨损变为粘着磨损,改善了合金的耐磨性能。     

DLC膜厚度对镁基表面DLC/MAO复合膜层性能的影响

采用线性离子束沉积技术于AZ80镁合金微弧氧化(MAO)陶瓷层表面沉积不同厚度的类金刚石碳(DLC)膜,形成DLC/MAO复合膜层。对比研究4种膜基系统的表面结构特征、力学性能以及摩擦学性能差异。结果表明:随DLC膜厚度增加,复合膜层表面微孔数量减少,孔径减小,但凹凸不平趋势增加,且DLC膜表面颗粒特征更加明显,表现为DLC-80min/MAO/AZ80膜基系统具有最小的表面粗糙度,最大的硬度H、弹性模量E及H/E值;不同厚度DLC/MAO/AZ80膜基系统平均摩擦因数较MAO/AZ80显著降低;DLC膜厚度增加导致3种复合膜基系统的表面微观结构改变,使得摩擦因数与磨痕形貌存在差异;各膜基系统表面磨痕处均形成了Fe的转移层,由于表层DLC膜"裸露"的大量C对磨损界面具有很好的润滑作用,而使得镁合金基体获得有效保护。     

Microstructure and properties of ceramic coatings produced on 2024 aluminum alloy by microarc oxidation

The microstructures of the microarc oxidation coatings and 2024 aluminum alloy substrate were observed using the scanning electron microscope (SEM) and the phase composition of the coatings was analyzed by X-ray diffraction (XRD). Furthermore, the profiles of the nanohardness, H, and elastic modulus, E, along the coating depth were first determined using the mechanical properties microprobe. The microarc oxidation coatings consist of two layers—a loose layer and a compact layer. The H and E in the compact layer are about 18–32 GPa, 280–390 GPa, respectively. The H and E profiles are similar, and both of them exhibit a maximum value at a same depth of the coatings. The distribution of -Al₂O₃ phase content determines the H and E profiles in the coatings. The changes of -Al₂O₃ and -Al₂O₃ contents result from the different cooling rates of the molten alumina in the microarc discharge channel at the different depths of the coatings. After the microarc oxidation treatment, the microstructure of the alloy substrate, even near the Al/Al₂O₃ interface, has not been changed.     

Effect of Negatively Charged Ions on the Formation of Microarc Oxidation Coating on 2024 Aluminium Alloy

The present study deals with the effect of negatively charged ions on the ceramic coating formation on 2024 aluminium alloy during microarc oxidation (MAO) process. On the basis of the experimental results, two steps (the formation of an incipient film without arc presence and the growth of a ceramic coating with arc discharge) of MAO process have been observed. For comparison, four different negatively charged ions studied. It is proved that negatively charged ions strongly participated in the formation of an incipient film with high impedance value at the first step. The growth of ceramic coating depends on the combination between Al of the substrate and O from the electrolyte, and the negatively charged ions are little consumed. As an anodic oxide coating is prepared on the sample surface instead of the incipient film, the first step occurs easily and the growth of ceramic coating is accelerated. Furthermore, the mechanism of negatively charged ions in the formation of the MAO coating has been proposed.     

SiC纳米颗粒对TC4钛合金微弧氧化涂层组织结构及耐蚀性能的影响

在基础电解液中加入SiC纳米颗粒,利用微弧氧化技术在TC4钛合金表面制备微弧氧化陶瓷涂层,研究纳米颗粒的添加对微弧氧化涂层组织结构及耐蚀性能的影响。结果表明:550,600V及650V条件下,基础电解液中SiC的加入,使TC4微弧氧化涂层的厚度由9.2,12.8μm和12.4μm分别增大到12.0,14.9μm和20.0μm。随着电压的升高,微弧氧化涂层的表面粗糙度逐渐增大,分别为2.65, 3.34μm和3.61μm。SiC的加入有效抑制微弧氧化涂层表面裂纹的产生,增加涂层厚度从而降低涂层的阳极电流密度,提高微弧氧化涂层的耐蚀性能。微弧氧化涂层增加了TC4的开路电位及自腐蚀电位。     

Ti35Nb7Zr-xHA生物复合材料的微观组织与性能研究

为了改善Ti-Nb-Zr合金的生物活性,采用放电等离子烧结(SPS)技术制备了不同羟基磷灰石(HA)含量的Ti35Nb7Zr-xHA(x=0、5、10、20(质量分数,%))生物复合材料,研究了HA含量对复合材料微观组织、力学性能及体外生物活性的影响。结果表明,复合材料主要由β-Ti、α-Ti、HA及陶瓷相(Ti_xP_y、CaTiO_3、Ti_2O、CaO)组成;HA含量增加会导致β-Ti减少而α-Ti和陶瓷相明显增多;与Ti-35Nb-7Zr合金(E:45GPa,σ:1 736 MPa)相比,HA含量为5%和10%时,复合材料的抗压强度分别为1 662MPa和1 593MPa,弹性模量分别为48GPa和49GPa,综合力学性能与Ti-35Nb-7Zr合金接近,展现出良好的力学性能,而过高的HA含量(20%)会导致复合材料弹性模量明显升高(E:55GPa)、抗压强度急剧下降(σ:958 MPa),复合材料的力学性能降低;体外生物活性实验表明,加入10%HA的复合材料在人工模拟体液(SBF)中浸泡7d后表面生成了大量的类骨磷灰石层,与Ti-35Nb-7Zr合金相比,其显示出更优异的体外生物活性。     

Structure, mechanical and tribological properties of diamond-like carbon films on aluminum alloy by arc ion plating

The low hardness and poor tribological performance of aluminum alloys restrict their engineering applications. However, protective hard films deposited on aluminum alloys are believed to be effective for overcoming their poor wear properties. In this paper, diamond-like carbon (DLC) films as hard protective film were deposited on 2024 aluminum alloy by arc ion plating. The dependence of the chemical state and microstructure of the films on substrate bias voltage was analyzed by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical and tribological properties of the DLC films deposited on aluminum alloy were investigated by nanoindentation and ball-on-disk tribotester, respectively. The results show that the deposited DLC films were very well-adhered to the aluminum alloy substrate, with no cracks or delamination being observed. A maximum sp³ content of about 37% was obtained at −100 V substrate bias, resulting in a hardness of 30 GPa and elastic modulus of 280 GPa. Thus, the surface hardness and wear resistance of 2024 aluminum alloy can be significantly improved by applying a protective DLC film coating. The DLC-coated aluminum alloy showed a stable and relatively low friction coefficient, as well as narrower and shallower wear tracks in comparison with the uncoated aluminum alloy.     

Influence of oxygen content on microstructure and mechanical properties of Ti–Nb–Ta–Zr alloy

The influence of oxygen content on microstructure and mechanical properties of Ti–22.5Nb–0.7Ta–2Zr (at.%) alloy was investigated in this work. According to experiments, the grains were refined apparently when the oxygen content was between 1.5% and 2.0%. The ultimate tensile strength (UTS) increased and elongation decreased with increasing oxygen content. But at the content of 1.0%, the elongation was nearly the same to that of the original alloy (about 16%). The elastic modulus remained comparatively low (<65 GPa) when the content was lower than 1.5%, and then increased dramatically. Therefore, there existed the best oxygen content-1.0%, at which fine grains were obtained, as well as UTS of 750 MPa, elongation of 16% and elastic modulus of 65 GPa. The Ti–22.5Nb–0.7Ta–2Zr–1.0O alloy maintained typical ductile fracture characteristics of beta titanium alloy, and had a little superelasticity.