酸刻蚀处理对IrO2-Ta2O5/Ti阳极寿命的影响

通过改变腐蚀方法,研究了使用H₂C₂O₄和H₂SO₄进行钛基体表面刻蚀对金属氧化物钛阳极电化学性能和表面形貌的影响。采用扫描电子显微镜、X射线衍射仪和光电子能谱等测试方法对样品进行了结构分析。然后利用电化学工作站测试了样品的电催化活性,利用加速寿命测试研究了样品的电化学稳定性。结果表明,通过H₂C₂O₄和H₂SO₄分步腐蚀可以获得更加均匀致密的表面形貌和更好的催化稳定性。在此基础上,进一步研究了预处理对钛阳极寿命的影响原因。IrO₂-Ta₂O₅/Ti阳极的催化活性和稳定性与酸刻蚀处理的先后顺序及表面结构密切相关,并建立了预处理方法与阳极性能之间的关系。分步腐蚀使钛表面具有合适的粗糙度,因而提升了涂层附着力。在热分解过程中,经分步腐蚀形成的氢化钛在不改变表面形貌的情况下转变为金红石结构的氧化钛,有利于电子输运,从而增强涂层附着力并延长加速寿命。     

Mn掺杂提高IrO2-Ta2O5 电极在硫酸溶液中析氧的电催化活性

制备了不同 Mn 含量的IrO₂-Ta₂O₅-MnO_x电极。揭示了Mn含量对该类电极的物理和电化学特性的影响。结果表明,涂??覆的IrO₂-Ta₂O₅-MnO_x层由于其凹凸不平的多孔结构而具有较大的比表面积。少量Mn的加入抑制了活性成分IrO₂的结晶,并将其转化为Ir³⁺。适当地用 Mn 代替Ir可以显著提高 IrO₂-Ta₂O₅-MnO_x 电极的电催化性能。高的电催化活性、长的寿命和低的成本得益于 Mn 掺杂的电极具有更大的活性表面积,从而促进了硫酸溶液中氧的析出。     

激光辅助热喷涂NiCoCrAlYTa/ZrO2/BaF2·CaF2涂层的组织及性能∗

高温耐磨涂层是航空发动机关键摩擦副可靠使用的重要保障,鉴于其服役环境日益严苛复杂,进一步提高涂层的高温耐磨性能是十分必要的。利用激光辅助热喷涂技术制备 NiCoCrAlYTa / ZrO₂ / BaF₂·CaF₂ 高温耐磨涂层,利用 SEM、EDS 分析高温耐磨涂层的横截面微观组织及化学成分,研究 ZrO₂ / BaF₂·CaF₂质量分数、激光功率及扫描速度对耐磨涂层微观组织、力学性能及高温耐磨性能的影响。结果表明：激光辅助处理可以诱导耐磨涂层表面形成具有树枝状结构的 ZrO₂陶瓷层; 当激光功率为 80 W,扫描速度为 8 mm / s,喷涂粉末为 75 wt.% NiCoCrAlYTa+25 wt.% ZrO₂ / BaF₂·CaF₂时,制备涂层的微观组织、综合力学性能及高温耐磨性能达到最好;在此工艺参数下,涂层顶部的 ZrO₂ 陶瓷层最为致密均匀,其平均纳米硬度为 13.6 GPa,平均弹性模量为 182.5 GPa,800 ℃时的磨损率为 2.7×10^?5 mm³ ·N^?1 ·m^?1 。将高温耐磨涂层的组分设计与激光辅助热喷涂工艺相结合,可为提高涂层综合性能的提供解决途径。     

NiMoO4/g-C3N4的制备及电化学性能研究

超级电容器具有比电容高、循环寿命长和绿色无污染的特点,其优异的电化学性能备受关注。本文水热合成了NiMoO₄/g-C₃N₄复合粉体,并将粉体涂覆在泡沫镍上制备了NiMoO₄/g-C₃N₄电极材料。结果表明,NiMoO₄/g-C₃N₄粉体形貌主要为NiMoO₄纳米棒和团状g-C₃N₄,且NiMoO₄纳米棒生长在g-C₃N₄纳米片上。在NiMoO₄中加入30at%的g-C₃N₄能降低电容体系的等效串联电阻和扩散阻抗,有利于氧化还原反应的进行。相比于其他g-C₃N₄含量的电极材料,g-C₃N₄含量为30at%的NiMoO₄/g-C₃N₄电极材料具有更高的比电容(584.3F/g)和更好的倍率特性。     

铝合金表面MoS2/Al2O3复合涂层制备及减摩性能研究

铝合金表面减摩涂层设计和制备是改善铝合金构件摩擦性能的关键技术之一。对于目前铝合金结构件易磨损的问题,本研究采用微弧氧化一步法在6063铝合金表面原位合成纳米MoS2,制备具有减摩作用的MoS2/Al2O3复合陶瓷涂层;讨论了硫盐浓度对涂层成分、形貌及摩擦性能的影响,分析了涂层减摩机理。结果表明：通过微弧氧化在6063铝合金表面成功制备出了含有MoS2的自润滑复合陶瓷涂层;涂层的摩擦系数随着硫盐浓度的升高呈现先下降后上升的趋势,当电解液中硫盐浓度为15g/L时涂层的摩擦系数为0.15,较常规微弧氧化涂层降低了76%。涂层中的MoS2分布在涂层的表面和内部,在与摩擦副接触与挤压的作用下形成均匀分布的MoS2润滑膜,表现出良好的减摩性能。     

Ba(Mg1/3Ta2/3)O3热障涂层的制备及抗热震性能研究

本文以BaCO₃、MgO、Ta₂O₅为原料,采用固相反应法合成了Ba(Mg_1/3Ta_2/3)O₃(简称BMT)陶瓷粉末,利用大气等离子喷涂技术制备了BMT/YSZ双层陶瓷涂层。利用XRD、SEM和金相显微镜检测了BMT粉体及涂层的物相组成和显微结构。采用水淬法考核了涂层的抗热震性能。结果表明：1450℃下煅烧4h可合成出具有复合钙钛矿结构的BMT粉末,粉末具有良好的高温相结构稳定性。等离子喷涂制备的BMT/YSZ涂层组织致密,涂层系统中各界面结合紧密。涂层在室温至1150℃间热震9次后发生片状剥落,剥落位置位于BMT层间,BMT材料低的断裂韧性和第二相Ba₃Ta₅O₁₅的存在是导致涂层失效的主要原因。     

La掺杂对Ti/Sb-SnO2电极改性机制的研究：电化学分析

为研究稀土掺杂对Ti/Sb-SnO_2催化电极的改性机理,采用溶胶凝胶法制备了La掺杂Ti/Sb-SnO_2电极,以苯酚为目标有机物,考察了电极的电化学性能。极化曲线和Mott-Schottky分析表明:La改性Ti/Sb-SnO_2电极的析氧电位先增大后减小,且在2.0 V电位下Sn:Sb:La(摩尔比)为100:10:1.5时电极交换电流密度值最大;改性后电极的平带电势负移,Mott-Schottky拟合直线斜率从2.96降为1.66,活性表面积增大,载流子浓度提升。循环伏安和交流阻抗分析表明:掺杂后电极电化学反应电阻减小,活性电荷由14.1μF提升至322μF;苯酚直接氧化峰电流增大,峰电位减小。以上结果解释了电极电催化活性提升的内在原因。     

不同酸处理对钛基体性能的影响

本研究在保持酸度和温度一致的条件下分别用草酸、硫酸及盐酸对TA2钛基体进行刻蚀处理,研究不同种类酸处理对钛基体及后续电极性能的影响。研究表明:钛基体在草酸和硫酸中的质量损失率要大于在盐酸中的损失率。金相及SEM观察表明:草酸对钛基体刻蚀效果最好,刻痕细致均匀。强化寿命测试结果显示:经草酸处理后的Sn-Sb氧化物涂层钛基电极强化寿命最长。循环伏安测试结果表明:3种酸刻蚀过后的Sn-Sb氧化物涂层电极的析氧电位基本相同,表明酸刻蚀对于该电极的析氧电位影响不大。     

Ni2Cr(BO3)O2涂层的制备及其红外发射性能

通过喷雾造粒和高温焙烧制备Ni_2Cr(BO_3)O_2粉末后利用等离子喷涂得到一种高红外发射涂层,并研究了该种涂层的红外发射性能。SEM观察涂层的表面、断面形貌,发现涂层与基体结合紧密、无脱落;XRD对焙烧后的粉末物相组成进行了表征,主要以Ni_2Cr(BO_3)O_2为主。对涂层红外波段发射率的测试表明,在0.76~2.5μm波段的发射率为0.896、2.5~14μm波段发射率为0.925,具有优异的红外发射性能。Ni_2Cr(BO_3)O_2晶胞内的畸变、非对称性以及电子转移跃迁是导致Ni_2Cr(BO_3)O_2这种材料具有高红外发射率的主要原因。Ni_2Cr(BO_3)O_2涂层能够经受37次"900℃~水冷"热震循环。该种涂层由于其高红外发射性能、优异的耐热震性能和热稳定性能而具有较高的实用价值。     

SnO2 增强相对AgCuOIn2O3 电触头材料显微组织与性能的影响

采用反应合成法结合塑性变形工艺制备了不同SnO₂含量的AgCuOIn₂O₃SnO₂电触头材料,利用扫描电镜和金相显微镜表征了材料的微观形貌及显微组织,分析对比了不同SnO₂含量的材料金相组织及其增强相的分布均匀性,并利用X射线衍射分析了材料的物相结构。测量了材料的抗拉伸强度、硬度、电阻等性能。结果表明：添加适量的SnO₂能使组织中的孔隙尺寸缩小、其他缺陷明显减少。氧化物弥散分布在银基体中,极大地改善了AgCuOIn₂O₃电触头材料的显微组织均匀性。在SnO₂含量不变时,材料的电阻率随塑性变形程度增加而有所降低;随着SnO₂含量增多,电阻率呈现先降低后升高的趋势,最后趋于定值,约为2.4 μΩ·cm。添加SnO₂后各试样材料的硬度均显著升高,SnO₂含量为1%（质量分数）的材料具有最优的抗拉伸强度和延伸率。     

Ti/IrO2+MnO2电极在酸性溶液中的析氧反应动力学研究

采用涂覆热分解法制备Ti/IrO₂+MnO₂复合电极,利用慢速线性电位扫描伏安法测试Ti/IrO₂+MnO₂电极的准稳态极化曲线并深入地研究析氧反应动力学,得到了相关动力学参数、反应历程及速度控制步骤。通过分析经欧姆电压降修正的Tafel曲线,较好地解释了Tafel直线区域的双斜率现象,基于此提出析氧反应动力学方程并进行数学推导,较好地符合实验结果。实验所得氢离子反应级数约为零,低电位区与高电位区的表观活化能分别为30.31和13.64 kJ/mol,进一步证明该数学模型的正确性。     

Degradation mechanism of long service life Ti/IrO2-Ta2O5 oxide anodes in sulphuric acid

Ageing performances of long service life Ti/70%IrO₂-30%Ta₂O₅ (at mole fraction) anodes prepared at 450 °C over the whole electrolysis time in H₂SO₄ solution have been investigated. It is showed that, the whole electrolysis processes of these anodes can be divided into three stages consisting of `active', `stable' and `de-active' regions. In the first two stages, the dissolution of coated oxides is dominated (with IrO<sub>2</sub> component preferential loss) which results in decreasing of apparent current for oxygen evolution and voltammetric charge. It is found that, in these two stages, the preferential orientations of (1 1 0) and (1 0 1) planes in IrO<sub>2</sub> rutile decreases with electrolysis time, and that of (0 0 2) plane increases, while the preferential orientations remain to be stabilized in the `de-active' region. Therefore, the loss mechanism of catalyst coatings in this region is changed. Electrochemical impedance spectroscopy measurement shows a slight increase in reaction resistance (R_ct) of oxide catalysts for oxygen evolution in the `de-active' region, while a sharp rise in totally physical impedance of the whole anode. According to the experimental results, a degradation mechanism of the Ti based anodes has been proposed by degradation of Ti/catalyst layer interface resulting from the dissolution and anodic oxidation of metal base alternatively.     

成分配比对Ti/IrO2-Ta2O5电极电容性能影响

摘要：采用低温热分解法制备了Ti基IrO2-Ta2O5氧化物涂层电极。通过X射线衍射(XRD),循环伏安曲线,交流阻抗谱,恒流充放电等测试方法分析了Ta含量对IrO2-Ta2O5氧化物涂层组织结构及电容性能的影响。结果表明,Ta2O5可抑制IrO2的晶化程度。随涂层中Ta含量增加,晶化度降低。当Ta含量为60mol%时,IrO2-Ta2O5电极的结晶度为6.4%,具有较小的电荷转移电阻和最高的比电容（239.2F/g）,比IrO2电极比电容(54.1F/g)提高了近4倍。     

Effects of K2O-Li2O doping on surface and catalytic properties of Fe2O3/Cr2O3 system

The effects of K₂O and Li₂O-doping (0.5, 0.75 and 1.5 mol%) of Fe₂O₃/Cr₂O₃ system on its surface and the catalytic properties were investigated. Pure and differently doped solids were calcined in air at 400-600 °C. The formula of the un-doped calcined solid was 0.85Fe₂O₃:0.15Cr₂O₃. The techniques employed were TGA, DTA, XRD, N₂ adsorption at −196 °C and catalytic oxidation of CO oxidation by O₂ at 200-300 °C. The results revealed that DTA curves of pure mixed solids consisted of one endothermic peak and two exothermic peaks. Pure and doped mixed solids calcined at 400 °C are amorphous in nature and turned to α-Fe₂O₃ upon heating at 500 and 600 °C. K₂O and Li₂O doping conducted at 500 or 600 °C modified the degree of crystallinity and crystallite size of all phases present which consisted of a mixture of nanocrystalline α- and γ-Fe₂O₃ together with K₂FeO₄ and LiFe₅O₈ phases. However, the heavily Li₂O-doped sample consisted only of LiFe₅O₈ phase. The specific surface area of the system investigated decreased to an extent proportional to the amount of K₂O and Li₂O added. On the other hand, the catalytic activity was found to increase by increasing the amount of K₂O and Li₂O added. The maximum increase in the catalytic activity, expressed as the reaction rate constant (k) measured at 200 °C, attained 30.8% and 26.5% for K₂O and Li₂O doping, respectively. The doping process did not modify the activation energy of the catalyzed reaction but rather increased the concentration of the active sites without changing their energetic nature.     

Growth of HT-LiCoO2 thin films on Pt-metalized silicon substrates

Layered LiCoO2 （HT-LiCoO2） films were grown on Pt-metalized silicon （PMS） substrates and polished bulk nickel （PBN） substrates by pulsed laser deposition. The effects of substrate temperature, oxygen pressure, and substrate surface roughness on the microstructure of LiCoO2 films were investigated. It has been found that a higher substrate temperature and a higher oxygen pressure favor the formation of better crystallized and less lithium-deficient HT-LiCoO2 films. The HT-LiCoO2 film deposited on PBN substrates consists of large randomly orientated equiaxial grains, whereas on PMS substrate, it is made up of loosely packed highly [001] preferential orientated triangular shaped grains with the average grain size less than 100 nm. Electrochemical measurements show that the highly [001] preferentially orientated nanostructured HT-LiCoO2 thin film grown on PMS substrate has good structural stability upon lithium insertion/extraction and can deliver an initial discharge capacity of approximately 45μA·h·cm^-2·μm^-1 with a cycling efficiency of above 99% at the charge/discharge rate of 0.5 C.     

Production of MgB2 superconducting coatings by electrophoresis on metal substrates

Production of MgB₂ coatings on various metallic substrates was achieved by means of the direct electrophoretic deposition technique. An inexpensive simple heat treatment in evacuated quartz tubes was developed as an alternative to inert gas flow during the process. The films were characterized by XRD, SEM and SQUID. It resulted that the procedure led to the production of uniform, dense and well-adhesive superconducting films. Stainless steel proved to be the best substrate among the investigated metals.     

Microstructure and mechanical properties of Al2O3-Cr2O3 composite coatings produced by atmospheric plasma spraying

Al₂O₃, Al₂O₃-Cr₂O₃ and Cr₂O₃ coatings were deposited by atmospheric plasma spraying. Phase composition of powders and as-sprayed coatings was determined by X-ray diffraction. Electron probe microanalyzer was employed to investigate the polished and fractured surface morphologies of the coatings. Mechanical properties including microhardness, fracture toughness and bending strength were evaluated. The results indicate that the addition of Cr₂O₃ is conducive to the stabilization of α-Al₂O₃. Compared with the pure Al₂O₃ and Cr₂O₃ coatings, Al₂O₃-Cr₂O₃ composite coatings show lower porosities and denser structures. Heterogeneous nucleation of α-Al₂O₃ occurs over the isostructural Cr₂O₃ lamellae and partial solid solution of Al₂O₃ and Cr₂O₃ might be occurring as well. Furthermore, grain refining and solid solution strengthening facilitate the mechanical property enhancement of Al₂O₃-Cr₂O₃ composite coatings.