超音速大气等离子喷涂TiB2-SiC涂层的抗氧化性及耐熔盐腐蚀性能

采用超音速大气等离子喷涂制备全包覆TiB₂-SiC涂层,研究了TiB₂-SiC涂层在400和800 ℃的氧化性能,并探究其氧化机理。对TiB₂-SiC涂层在900 ℃下的抗铝熔盐腐蚀性能进行研究,并探讨其耐熔盐腐蚀机理。结果表明,超音速大气等离子喷涂制备的TiB₂-SiC涂层具有良好的抗氧化性,在400 ℃的氧化速率常数为1.92×10^-5 mg²·cm^-4·s^-1,在800 ℃的氧化速率常数为1.82×10^-4 mg²·cm^-4·s^-1。超音速大气等离子喷涂制备的TiB₂-SiC涂层在900 ℃下具有良好的抗熔盐腐蚀性能,熔盐腐蚀后TiB₂-SiC涂层都保持致密结构,未发生涂层的开裂及剥落。     

钛合金表面TiB2涂层与纯铝的高温黏着磨损行为*

航空发动机低压气机机匣内表面 Al 基封严涂层的使用,可以通过其自身的磨耗实现保护 TC4 叶尖的目的,但同时 Al 基封严涂层中以 Al 为主的基体材料易于大量黏着转移至 TC4 叶尖表面,使叶尖长度增加,影响发动机运行稳定性。采用直流脉冲磁控溅射工艺在钛合金表面沉积 TiB₂ 涂层,以期实现抗 Al 黏着磨损目的。具有致密结构的 TiB₂涂层在钛合金表面膜基结合临界载荷(L_C4)达 85.4 N。在高温销-盘摩擦磨损试验机上评价钛合金表面 TiB₂涂层与纯铝销对摩(室温至 450 ℃) 的抗 Al 黏着磨损性能。与 TC4 基体相比较,TiB₂ 涂层可有效抑制 Al 的黏着转移。对摩铝销磨斑具有拖尾特征和剪切舌特征。 铝销向 TiB₂涂层表面的机械涂抹和铝销对 Al 黏着转移层的剪切去除作用相互竞争,共同控制 Al 的黏着转移行为。TiB₂涂层磨痕内保持低表面粗糙度可减小高温软化铝销的机械涂抹倾向。同时 TiB₂涂层与 Al 黏着转移层间优异的化学稳定性可阻碍界面反应进行,降低界面结合强度,进而促进铝销对 Al 黏着转移层的剪切去除作用。钛合金表面 TiB₂ 涂层通过抑制铝销机械涂抹并增强铝销对 Al 黏着转移层的剪切去除而获得优异的抗 Al 黏着磨损性能。     

电流密度对ZK60镁合金表面超疏水涂层的制备及耐腐蚀性的影响

为了提高镁合金的耐腐蚀性能,基于层状双氢氧化物（LDHs）膜在ZK60镁合金表面制备了超疏水（SH）涂层。涂层制备过程中引入电场辅助,研究了工作电流密度对涂层性能的影响。结果表明,工作电流密度显著影响LDHs膜的微观结构,这对SH涂层的疏水性具有重要影响。当工作电流密度为25 mA/cm²时,SH涂层表面呈现均匀的微纳米结构,并表现出超疏水性。超疏水涂层的腐蚀电流密度（I_corr=9×10^-7 A·cm^-2）比ZK60基体的腐蚀电流密度（I_corr=3×10^-5 A·cm^-2）低了2个数量级,表现出优异的耐腐蚀性。     

氩弧熔敷原位合成TiC-TiB2/Ti基复合涂层组织及性能分析

利用氩弧熔敷技术,在TC4合金表面原位合成了TiC-TiB₂增强镍基复合材料涂层,利用SEM和XRD等方法分析了涂层的显微组织并测试了涂层的显微硬度.结果表明,熔敷组织主要由TiC,TiB₂和Ti(Ni,Cr)组成,TiB₂主要以棒状形式存在;在所形成的TiC-TiB₂/Ti复合材料层中,TiC和TiB₂颗粒分布均匀且尺寸细小;熔敷涂层由表及里组织不同;熔敷层与基体呈冶金结合,无气孔、裂纹等缺陷;涂层的显微硬度达到13.8 GPa,较基体提高了4.5倍.     

机械能助渗锌铝渗层的防腐耐磨性能分析

高温高湿高盐雾苛刻环境中螺栓件的腐蚀问题备受广大学者关注。 结合紧固件装配需求,采用机械能助渗技术在 450 ℃温度下制备 Zn-Al 功能渗层。 通过扫描电子显微镜( SEM)、能谱分析(EDS)、显微硬度计、X 射线衍射仪 (XRD)等对锌铝渗层的厚度、物相、硬度和形貌进行表征,采用电化学工作站和摩擦磨损试验机对锌铝渗层的防腐耐磨性能进行研究。 结果表明:机械能助渗制备的锌铝渗层有利于提高基体的防腐耐磨性能。 当锌粉的质量分数为 35%、 铝粉为 15%,保温时间为 4. 5 h,渗炉转速为 7 r/ min 时,涂层呈现出最佳的防腐耐磨性能。 此渗层主要由 Al₂O₃ 、Γ1 相(Fe₁₁Zn₄₀ )和 δ1 相( FeZn_{6. 67}、 FeZn_{8. 87}、 FeZn_{10. 98})组成,其厚度为 91. 12 μm,表面硬度为 413. 2 HV_{0. 05},腐蚀电位为 -0. 9286 V,腐蚀电流密度为 2. 2493 A·cm^-2,低频区阻抗模值为 2284 Ω·cm²,平均摩擦因数为 0. 3887,磨痕宽度为 734. 66 μm,磨痕深度为 21. 7 μm,磨损体积为 16. 75×10^-3mm³。     

超疏水涂层的制备及其对Mg-Li合金的防腐蚀性能

以正硅酸乙酯(TEOS)为原料,采用溶胶-凝胶法合成纳米 SiO₂ ,并用乙烯基三甲氧基硅烷(VTMS)进行表面改性,在高化学活性的镁锂(Mg-Li)合金表面制备了超疏水防腐蚀涂层。 利用红外光谱(FTIR)分析 SiO2 和改性 SiO₂ 的化学结构,通过扫描电子显微镜(SEM)观察不同氨水含量下制备的超疏水涂层的表面形貌。 采用接触角(CA) 测试超疏水涂层的疏水性,通过电化学阻抗谱(EIS)和动电位极化曲线分析超疏水涂层的防腐蚀性能,采用 X 射线光电子能谱 (XPS)分析 Mg-Li 合金表面的化学成分变化情况。 结果表明,当所用氨水与 TEOS 的质量比达到 1 ∶1时,制备的超疏水涂层表面表现出良好的粗糙度,接触角达到 151°,滚动角只有 5°。 超疏水纳米 SiO₂ 涂层对 Mg-Li 合金具有良好的防腐蚀性能,阻抗值达到 10⁵ Ω,腐蚀电流密度仅为 6. 19×10^-8 A/ cm² 。     

TiO2纳米管沉积NiMo合金纳米阵列制备高效HER催化剂

制备高效稳定的非贵金属催化剂对于电解水生产高纯度氢气的发展至关重要。本实验通过简单的阳极氧化法和电沉积方法制备NiMo/TNAs复合催化剂,将NiMo合金颗粒通过电沉积方法稳固包覆于TNAs独特的弯曲有序界面上,当沉积电流和电解液Mo离子浓度变化时,NiMo的沉积状态和催化能力也随之改变,经过研究表明,在沉积电流密度15mA.cm_^-2,Mo离子浓度4g.L_^-1条件下沉积1min制备的样品具有更高的HER催化性能。通过更大活性表面积,更便捷的离子传输通道和增强的结构稳定性,获得了优异的催化活性的NiMo/TNAs电催化剂。NiMo/TNAs催化剂的起始过电位仅为50mV,分别在110mV和227mV低过电势下获得10mA.cm_^-2和100mA.cm_^-2的电流密度。因此得到结论,将NiMo合金颗粒沉积在TNAs纳米阵列,制备NiMo/TNAs催化剂为制备廉价高效电催化剂提供了新途径。     

AISI430铁素体不锈钢表面制备MnCo2O4涂层特性及内应力研究

为了探究MnCo₂O₄尖晶石涂层作为固体氧化物燃料电池的金属连接体表面涂层的性能,使用溶胶-凝胶法制备出纯净的前驱体粉末,再使用电泳沉积方法制备出致密的MnCo₂O₄尖晶石涂层,利用SEM、EDS和XRD等表征手段观察分析MnCo₂O₄尖晶石涂层的相结构和微观组织形貌。采用“四探针法”测量MnCo₂O₄尖晶石涂层800℃氧化200h前后的面比电阻使用拉拔法完成不同界面粗糙度下的涂层结合强度测试,并用有限元仿真加以验证。结果显示,MnCo₂O₄尖晶石涂层结构均匀,致密度较好。相较于AISI430不锈钢基体来说,在800℃空气中氧化200h,抗氧化性提高了接近3倍。且中温面比电阻小于SOFC金属连接体规定的极限值。此外,基体表面粗糙度可以有效的增加涂层与基体的机械咬合作用,但同时也会导致应力集中,出现缺陷,从而降低了结合强度。     

喷丸处理对45钢表面Al+注入层抗高温氧化性的影响

为改善45钢的抗高温氧化性能，在其表面制备单一Al⁺注入层和喷丸+Al⁺注入层。检测表征改性层的表面粗糙度、显微硬度、微观形貌、以及铝元素含量，并进行600℃、200 h下的抗高温氧化性能试验。研究结果表明：喷丸处理45钢表面呈现出凹坑、丘陵状、具有近似等轴状纳米晶结构，Al⁺注入使纳米晶进一步细化。喷丸处理使45钢的表面粗糙度Ra从0.42 μm增至1.15 μm，显微硬度、注入铝元素含量及氧化增重分别从单一Al⁺注入层的257 HV_0.05增至喷丸+Al⁺注入层的最高505 HV_0.05，从3.7%增至4.2%和从14.8 mg·cm^-2降至8.3 mg·cm^-2。即喷丸处理有效增强了45钢表面Al⁺注入层的抗高温氧化性能。     

298 K下离子液体BMIMPF6 中电沉积制备镧金属薄膜

以无水硝酸镧、1-丁基-3-甲基咪唑六氟磷酸（BMIMPF₆）和助溶剂丙酮为电解液,在室温（298 K）下电沉积制得镧金属薄膜。电解液BMIMPF₆的电化学窗口为-2.5~1.5 V vs. Pt,La³⁺还原为La²⁺发生于-1.7 V vs. Pt,La²⁺还原为La⁰发生于-2.1 V vs. Pt。BMIMPF₆的低吸湿性有利于在空气气氛下电沉积镧。使用扫描电子显微镜和光学显微镜观察到所制备的薄膜织构致密,经能量色散谱和X射线光电子能谱对沉积薄膜进行了表征,确定了薄膜中含有大量镧元素。通过探究电压扫描速率和硝酸镧浓度对La³⁺的电化学行为的影响,证明La³⁺的还原反应是一个受物质扩散控制的不可逆过程,La³⁺在BMIMPF₆中的扩散系数为1.47×10^-9 cm²·s^-1。本研究为获得金属镧薄膜和镧氧化物薄膜提供了一种简便的方法,并且有望用于电沉积制备其它镧系元素薄膜。     

改进型镁扩散法制备高临界电流密度MgB2超导体性能研究

本文采用一种改进型镁扩散法成功制备出密度达到1.95g/cm₃的MgB₂超导块材。论文研究了不同的热处理条件对MgB₂块材的超导转变温度(T_c)和临界电流密度(J_c)性能的影响。采用最佳热处理条件制备的MgB₂超导体T_c和J_c分别达到了38.1K和0.53MA/cm₂(10K,自场)。为了改进镁扩散法MgB₂超导体中弱的高场磁通钉扎性能,本文还研究了nano-Pr₆O₁₁和C掺杂对MgB₂超导体的临界电流密度和不可逆场(H_irr)的影响。结果表明C掺杂的MgB₂超导体临界电流密度在10K,6T下达到了10₄A/cm₂,该结果比未掺杂MgB₂超导体在同样条件下性能提高了两个量级,甚至比固态反应法制备的nano-C掺杂MgB₂超导体性能更好。利用该方法制备的nano-Pr₆O₁₁掺杂的MgB₂超导体在10K,2T下也比未掺杂样品J_c提高达9.4倍。根据大量的实验结果和理论分析我们提出基于改进型镁扩散法和化学掺杂,包括纳米粒子和C掺杂,很有可能是一种制备高性能MgB₂超导体非常有效的途径。     

废旧锂离子电池中Li, Fe和V的回收及xLiFePO4-yLi3V2(PO4)3的制备

由于LiFePO_4和Li_3V_2(PO_4)_3材料的特征相近,制备方法类似,提供了一种从废旧LiFePO_4和Li_3V_2(PO_4)_3混合电池中回收Li、Fe和V,再制备xLiFePO_4-yLi_3V_2(PO_4)_3的方法。在空气气氛中600℃热处理1h后,去除粘结剂PVDF使活性物质与集流体分离。调节Li、Fe、V和P摩尔比,球磨、锻烧,配制不同比例的xLiFePO_4-yLi_3V_2(PO_4)_3(x:y=5:1,7:1,9:1)复合电极材料。表征了其形貌、结构和电化学性能,结果表明,回收制备的复合材料将同时具备LiFePO_4和Li_3V_2(PO_4)_3两种材料的电化学性能,能显著改善LiFePO_4的倍率性能。     

Improved capacity and rate capability of Ru-doped and carbon-coated Li4Ti5O12 anode material

Pure Li₄Ti₅O₁₂, modified Li₄Ti₅O₁₂/C, Li₄Ru_0.01Ti_4.99O₁₂ and Li₄Ru_0.01Ti_4.99O₁₂/C were successfully prepared by a modified solid-state method and its electrochemical properties were investigated. From the XRD patterns, the added sugar or doped Ru did not affect the spinel structure. The results of electrochemical properties revealed that Li₄Ru_0.01Ti_4.99O₁₂/C showed 120 and 110 mAh/g at 5 and 10 C rate after 100 charge/discharge cycles. Li₄Ru_0.01Ti_4.99O₁₂/C exhibited the best rate capability and the highest capacity at 5 and 10 C charge/discharge rate owing to the increase of electronic conductivity and the reduction of interface resistance between particles of Li₄Ti₅O₁₂.It is expected that the Li₄Ru_0.01Ti_4.99O₁₂/C will be a promising anode material to be used in high-rate lithium ion battery.     

Preparation and characteristic of spherical Li3V2(PO4)3

Spherical Li₃V₂(PO₄)₃ was synthesized by using N₂H₄ as reducer. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that single-phase, spherical and well-dispersed Li₃V₂(PO₄)₃ has been successfully synthesized in our experimental process. Electrochemical behaviors have been characterized by charge/discharge measurements. The initial discharge capacities of Li₃V₂(PO₄)₃ were 123 mAh g⁻¹ in the voltage range of 3.0–4.3 V and 132 mAh g⁻¹ in the voltage range of 3.0–4.8 V.     

Alloyed W–(Co,Ni,Fe)–C phases for reaction sintering of hardmetals

It has been shown that W–Co–C phases could dissolve a substantial amount of metals such as V, Cr and Ta, which are known to positively influence the microstructure of hardmetals with respect to uniform grain size distribution and fine grain size. This offers a tool to circumvent the conventional doping of hardmetals with individual carbides. In the present study we used double- and triple-alloyed κ-W₉Co₃C₄ (i.e. κ-(W,V,Cr)₉Co₃C₄ and κ-(W,V,Cr,Ta)₉Co₃C₄) and applied a variety of sintering experiments to obtain WC–Co, WC–(Ti,Ta,Nb)C–Co and WC–(Ti,Ta,Nb)(C,N)–Co hardmetals. We also prepared κ-W₉Fe₃C₄, alloyed κ-W₉Ni₃C₄, and κ-W₉(Fe/Ni)₃C₄, and used the latter for sintering.     

Effects of Mo and Al Additions on the Sulfidation Behavior of 310 Stainless Steel

The high-temperature sulfidation behavior of 310stainless steel (310SS) with Mo and Al additions (up to10 at.%) was studied over the temperature range700-900°C in pure-sulfur vapor over the range of 10^-3 to 10^-1 atm. Thecorrosion kinetics followed the parabolic rate law inall cases and the sulfidation rates increased withincreasing temperature and sulfur pressure. Thesulfidation rates decreased with increasing Mo and Al contents and it wasfound that the addition of 10 at.% Mo resulted in themost pronounced reduction among the alloys studied. Thescales formed on 310SS with Mo additions were complex, consisting of an outer layer of ironsulfide (with dissolved Cr), (Fe,Ni)₉S₈, andCr₂S₃/Cr₃S₄(with dissolved Fe), and an inner heterophasic layer ofFe_1-xS,Cr₂S₃/Cr₃S₄,NiCr₂S₄,Fe_1.25Mo₆S_7.7, FeMo₂S₄, andMoS₂. The scales formed on 310SS with Mo andAl additions had a similar mixture as above, except thatAl_0.55Mo₂S₄ was alsoobserved in the inner layer. The formation ofMoS₂ andAl_0.55Mo₂S₄ partly blocked the transport of cations throughthe inner scale, resulting in the reduction of thesulfidation rates compared to 310SS.     

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.     

The high-temperature corrosion behavior of Nb-Al alloys in a H2/H2S/H2O gas mixture

The corrosion behavior of pure Nb and three Nb Al alloys containing 12.5, 25, and 75 at.% Al was studied over the temperature range of 800–1000°C in a H₂/H₂S/H₂O gas mixture. Except for the Nb-12.5Al alloy consisting of a two phase structure of -Nb and Nb₃Al, other alloys studied were single phase. The corrosion kinetics followed the parabolic rate law in all cases, regardless of temperature and alloy composition. The parabolic rate constants increased with increasing temperature, but fluctuated with increasing Al content. The Nb-75Al alloy exhibited the best corrosion resistance among all alloys studied, whose corrosion rates are 1.6–2.2 orders of magnitude lower than those of pure-Nb (depending on temperature). An exclusive NbO₂ layer was formed on pure Nb, while heterophasic scales were observed on Nb-Al alloys whose compositions and amounts strongly depended on Al content and temperature. The scales formed on Nb-12.5Al consisted of mostly NbO₂ and minor amounts of Nb₂O₅, NbS2, and -Al₂O₃, while the scales formed on Nb-25Al consisted of mostly Nb₂O₅ and some -Al₂O₃. The scales formed on Nb-75Al consisted of mostly -Al₂O₃ and Nb₃S₄ atT 900°C, and mostly -Al₂O₃ , Nb₃S₄ and some AlNbO₄ at 1000°C. The formation of -Al₂O₃ and Nb₃S₄ resulted in a significant reduction of the corrosion rates.     

固相-水热法制备LiFePO4-Li3V2（PO4）3复合材料及其电化学性能（英文）

分别采用固相-水热法和球磨法制备磷酸亚铁锂-磷酸钒锂复合正极材料(LiFePO4-Li3V2(PO4)3)。电化学性能测试表明,LiFePO4-Li3V2(PO4)3复合正极材料的电化学性能远远高于 LiFePO4和 Li3V2(PO4)3单独作为正极材料的性能,并且以固相-水热法制备的复合材料性能优于以球磨法制得的复合材料。研究发现 LiFePO4-Li3V2(PO4)3复合材料有 4 个氧化还原峰,相当于 LiFePO4 和 Li3V2(PO4)3 氧化还原峰的叠加。采用固相-水热法制备的LiFePO4-Li3V2(PO4)3 复合材料形貌较为规则,且有新相物质产生,这是导致其电化学性能较好的原因。     

Synthesis of lanthanum carbonate nanoparticles via sonochemical method for preparation of lanthanum hydroxide and lanthanum oxide nanoparticles

Lanthanum carbonate nanoparticles were synthesized from the reaction of lanthanum acetate and Na₂CO₃ under sonication via sonochemical method. Lanthanum hydroxide nanoparticles were prepared by facial hydrothermal processing from the resulted product at 110 °C for 24 h. The role of surfactant, calcination temperature and sonication time were investigated on the morphology and particle size of the products. Products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), and Fourier transform infrared (FT-IR) spectra. La₂O₃ nanoparticles were obtained by calcinations of the nanoparticles of lanthanum carbonate at 600 °C.