等离子喷涂La2Zr2O7热障涂层高温烧结的硬化行为

热障涂层在高温服役过程中发生烧结和硬化,是引发涂层开裂和剥离失效的主要因素,因此掌握涂层烧结规律是进行涂层设计制备、寿命预测和工艺优化的前提。 文中采用等离子喷涂技术制备 La₂ Zr₂ O₇热障涂层,在 1250 ℃ 条件下进行涂层高温热暴露试验,表征了涂层高温烧结过程中力学性能的变化规律,从孔隙结构的角度揭示了涂层高温烧结硬化机理。 研究结果表明,喷涂态 La₂ Zr₂ O₇ 涂层为典型的层状结构,硬度为(405±20) HV_0.3 ,高温热暴露后涂层呈现先快后慢的硬化趋势,热暴露 200 h 后涂层硬度提高了 80%。 涂层结构分析表明,涂层物相保持不变,但涂层孔隙率呈现出先快后慢的下降规律。 坐标轴变换处理后发现,硬度和孔隙率均呈现以 10 h 为临界的双阶段特性。 通过对涂层孔隙结构的高温准原位观察,发现涂层孔隙初期多点桥接超快愈合、后期以边界推进方式缓慢烧结的双阶段烧结现象, 从而揭示了 La₂ Zr₂ O₇ 热障涂层分阶段硬化的烧结机理,从而为发展抗烧结高性能热障涂层提供了新的理论依据。     

基于基团贡献法估算(富锂)锂离子电池正极材料Li1+ xM 1- x O2 的热力学性质

富锂Li_1+xM_1-xO₂材料的研究主要集中在其结构和电化学性能上,而很少关注其热力学性能。开发具有高能量密度和容量的新型富锂材料取决于这种材料的结构、热力学性质和电化学性质之间的固有关系。对富锂材料Li_1+xM_1-xO₂的热力学性质了解不足,使得新型Li_1+xM_1-xO₂材料的开发和利用受到限制。鉴于Li_1+xM_1-xO₂材料缺乏热力学数据,根据基团贡献方法的原理对LiAlO₂进行拆分。基于热力学原理,提出了用于估计LiAlO₂的ΔG^θ_f,298、ΔH^θ_f,298和C_p的数学模型。采用基团贡献法估算了56种固体无机化合物的ΔG^θ_f,298和ΔH^θ_f,298以及54种固体无机化合物的C_p,298,以检验该模型的可靠性和适用性。利用基团贡献法估算了固体无机化合物的数学模型。利用基团贡献法拟合的基团参数选择的实验数据准确可靠。在结果令人满意的基础上,建立了用于估算3种类型的Li_1+xM_1-xO₂材料的ΔG^θ_f,298,ΔH^θ_f,298和C_p的数学模型,并估算了63种常见Li_1+xM_1-xO₂材料的ΔG^θ_f,298、ΔH^θ_f,298和C_p,298。     

基于第一性原理的石榴石型Li_7La_3Zr_2O_(12)固态电解质的设计与合成（英文）

基于密度泛函理论(DFT)的第一原理方法计算了四方相和立方相中2种不同的Li_7La_3Zr_2O_(12)(LLZO)固体电解质材料的能带结构,晶格参数,态密度和成键特性。基于理论计算结果,通过电子结构特性解释了四面体相的离子电导率低于立方相的离子电导率的原因。基于LLZO的第一性原理计算,设计了2种晶体结构的LLZO材料,并通过高温固相法制备并分析了不同烧结时间的LLZO颗粒的性能。探索了合成工艺参数对Li_7La_3Zr_2O_(12)性能的影响。立方晶Li_7La_3Zr_2O_(12)(C-LLZO)的平均晶格大小为a=b=c=1.302 246 nm,而四方Li_7La_3Zr_2O_(12)(T-LLZO)的平均晶格大小为a=b=1.313 064 nm,c=1.266 024 nm。在1000℃下烧结12 h的C-LLZO为纯立方相,在室温(25℃)下最大离子电导率为9.8×10-5 S·cm-1。T-LLZO在室温(25℃)下的离子电导率为5.96×10-8 S·cm-1,在800℃下烧结6 h具有纯的四方相结构,与计算结果基本吻合。     

SNDC/La2Mo2O9复合电解质材料的制备及性能表征

本文采用甘氨酸-硝酸盐法(GNP)和溶胶凝胶法分别合成了Sm_0.1Nd_0.1Ce_0.8O_1.9(SNDC) 和La₂Mo₂O₉(LAMOX)粉末,并用常压烧结的方法制备了不同比例的SNDC和LAMOX的复合材料,通过XRD和SEM等手段表征了不同复合比例样品的物相和表面形貌并测试了烧结样品的电导率。结果表明,复合样品的电导率在相变点前后随着复合量增加变化趋势相反,其中LAMOX含量为20mol%的样品在550℃时的电导率能达到0.01S/cm,高于同温度下SNDC电导率。     

La2O3掺杂AgSnO2电接触材料的制备及性能研究

以Ag、Sn、La₂O₃粉为原料,采用机械合金法制备复合粉体。结合氧化法与粉末冶金工艺,对复合粉体进行氧化、压制、烧结。采用扫描电镜(SEM)和能谱仪、硬度计、金相显微镜、金属电导率测量仪等对复合粉体氧化前后的形貌以及电接触材料烧结前后的性能进行表征。结果表明：烧结后,电接触材料硬度较于烧结前明显下降。同时电接触材料随Sn含量增大,电阻率升高,密度反而下降。在一定的La₂O₃(0wt.%、0.75wt.%、1.5wt.%、2.25wt.%、3wt.%)含量范围内,La₂O₃掺杂量越高,密度越低。同时电接触材料经烧结后,随La₂O₃含量增加,其电阻率先降后升,在La₂O₃含量为0.75wt.%时,电接触材料的电阻率最低。     

0.74BiFe1- x Ga x O3-0.26BaTiO3 高温无铅压电陶瓷的相变行为及电性能

准同型相界（MPB）对提升压电陶瓷的压电性能具有重要的作用。BiFeO₃-BaTiO₃体系的准同型相界通常位于0.70BiFeO₃-0.30BaTiO₃组分附近。然而，对于BiFeO₃-BaTiO₃体系，BaTiO₃含量越高其居里温度越低。因此，在较低的BaTiO₃含量组分附近构建准同型相界是使其同时获得良好的压电活性和高居里温度的有效策略。采用固相法制备了0.74BiFe_1-xGa_xO₃-0.26BaTiO₃（x=0~0.05）系列无铅压电陶瓷，研究了Ga含量对其物相结构与电性能的影响。结果表明：随着Ga含量的增加，陶瓷样品从三方相逐渐向赝立方相转变。当x≤0.01，陶瓷样品为三方相结构；而当0.04≤x≤0.05，陶瓷样品为赝立方结构，在0.02≤x≤0.03形成了准同型相界（三方-赝立方）。另外，由于容忍因子的升高，该系列陶瓷的居里温度随着Ga含量的增加而略有降低。位于准同型附近的陶瓷样品表现出良好的压电活性和较高的居里温度。     

空气气氛下碳热还原筛分法制备Magnéli相Ti n O2 n -1

介绍了一种在空气气氛中通过碳热还原筛分法制备Magnéli相（Ti_nO_2n-1，4＜n＜10）低价钛氧化物的方法，研究了还原温度和还原时间对还原产物的物相、电阻率的影响。结果表明，提高还原温度和延长还原时间有利于将TiO₂还原为Magnéli相Ti_nO_2n-1。将Magnéli相Ti_nO_2n-1 (n=4，5) 粉末在1350 ℃下干燥20 min，通过扫描电子显微镜观察，其粒径为0.5~8 μm。在还原温度为1350 ℃时，还原产物的电阻率随还原时间的延长而显著降低。在1350 ℃下还原50 min的产物的电阻率最小，为79.3 Ω?cm，其物相组成几乎全部为Ti₃O₅。     

纳米柱状多孔WO3- x /TiO2 薄膜的电致变色性能

采用反应磁控溅射在掠射角度α=0°和α=80°的条件下制备氧化钨（WO_3-x）薄膜,然后在其表面沉积二氧化钛（TiO₂）。利用X射线衍射仪（XRD）、场发射扫描电镜（FE-SEM）和X射线光电子能谱仪（XPS）对WO_3-x/TiO₂薄膜的晶体结构、表面/断面形貌以及表面化学成分进行表征。在三电极体系1 mol/L LiClO₄/PC溶液中,采用电化学工作站和紫外-可见分光光度计测试了WO_3-x/TiO₂薄膜的电致变色性能。XRD结果表明,WO_3-x/TiO₂薄膜为非晶态结构,与掠射角度无关。当掠射角度为80°时,获得了纳米柱状多孔薄膜。从 W 4f和Ti 2p的XPS谱图确认氧化钨为亚化学计量比的WO_3-x,而氧化钛为满足化学计量比的TiO₂。与致密薄膜相比,纳米柱状多孔薄膜需要较低的驱动电压且具有较快的响应速度。纳米柱状多孔薄膜的电荷容量为83.78 mC,是致密薄膜电荷容量30.83 mC的2倍以上。在±1.2 V驱动电压下,注入和脱出离子扩散速率分别为D_in=5.69×10^-10 cm²/s和D_de= 5.08×10^-10 cm²/s。与纯WO₃薄膜相比,WO_3-x/TiO₂薄膜的电致变色循环稳定性更好。纳米柱状多孔薄膜在可见光范围内具有较大的光调制幅度,因此其光密度变化（ΔOD）大于致密薄膜。     

网孔结构La2Sn2O7粉体的制备及其在Ag-电接触材料的制备及性能研究

以五水四氯化锡和硝酸镧为原料,采用化学共沉淀法在烧结温度920℃条件下合成了锡酸镧粉体。通过高能球磨法+成型烧结工艺制得Ag-La₂Sn₂O₇电接触复合材料。重点考察了胶凝剂浓度、烧结工艺对La₂Sn₂O₇粉体形貌及物相的影响,并对Ag- La₂Sn₂O₇电接触材料的物理性能进行了分析。研究结果表明：以碳酸氢铵为胶凝剂,于烧结温度920℃,2h条件下获得具有网孔结构的La₂Sn₂O₇粉体;于成型压力1200MPa,烧结温度900℃,6h条件下制得的Ag-La₂Sn₂O₇电接触材料表现出较佳的电阻率和硬度值。经过热挤压工艺,Ag-La₂Sn₂O₇电接触材料发生了大塑性变形,颗粒在热挤压过程中发生流动变形,形成类纤维状结构的排列分布状态,表现出更低的电阻率。     

Ar/N2-Ar共溅射Ti掺杂对Ta2O5 涂层光学和力学性能的影响

为了探索Ar/N₂-Ar共溅射Ti掺杂对Ta₂O₅涂层光学性能和力学性能的影响,采用射频和直流磁控共溅射技术在玻璃基底表面制备了Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、原子力显微镜（AFM）表征了Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层的微观结构和表面形貌;通过紫外可见分光光度计测试了涂层的光学参数;采用纳米压痕仪测试了涂层的硬度和杨氏模量。XRD测试结果表明,Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层主要以Ta₂O₅为主体的非晶相结构组成。SEM和AFM结果显示,沉积在玻璃基底上的涂层未出现大面积空隙,溅射粒子在基底表面均匀堆积生长,并且涂层沉积厚度基本一致,厚度误差在5%以内。分别引入N₂和Ti及N₂-Ti共掺杂,均可降低Ta₂O₅涂层的粗糙度。光学测试结果表明,分别引入N₂和Ti元素,可以提高Ta₂O₅涂层的平均透射率至81%以上,而N₂-Ti共掺杂制备的N₂-Ti-Ta₂O₅涂层平均透射率降低。力学测试结果显示,与Ta₂O₅涂层对比,N₂-Ta₂O₅和N₂-Ti-Ta₂O₅涂层的硬度显著增大,Ti-Ta₂O₅涂层硬度基本一致。弹性指数（H/E）和塑性指数（H³/E²）表明,N₂-Ta₂O₅涂层和N₂-Ti-Ta₂O₅涂层具备更好的断裂韧性和抗塑性变形能力。在玻璃表面制备Ta₂O₅掺杂N₂和Ti元素的涂层,可以实现以N₂-Ta₂O₅涂层和N₂-Ti-Ta₂O₅涂层为代表的、同时具备优异光学性能和力学性能的多功能涂层。     

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.     

Sinterability and dielectric properties of Ba0.55Sr0.4Ca0.05TiO3-CaTiSiO5-Mg2TiO4 composite ceramics

The composite ceramics of Ba_0.55Sr_0.4Ca_0.05TiO₃-CaTiSiO₅-Mg₂TiO₄ (BSCT-CTS-MT) were prepared by the conventional solid-state route. The sintering performance, phase structures, morphologies, and dielectric properties of the composite ceramics were investigated. The BSCT-CTS-MT ceramics were sintered at 1100 °C and possessed dense microstructure. The dielectric constant was tailored from 1196 to 141 as the amount of Mg₂TiO₄ increased from 0 to 50 wt%. The dielectric constant and dielectric loss of 40 wt% Ba_0.55Sr_0.4Ca_0.05TiO₃-10 wt% CaTiSiO₅-50 wt% Mg₂TiO₄ was 141 and 0.0020, respectively, and the tunability was 8.64% under a DC electric field of 8.0 kV/cm. The Curie peaks were broadened and depressed after the addition of CaTiSiO₅. The optimistic dielectric properties made it a promising candidate for the application of tunable capacitors and phase shifters.     

Low temperature sintering and microwave dielectric properties of (Mg0.7Zn0.3)0.95Co0.05TiO3 ceramics with BaCu(B2O5) additions

The effects of BaCu(B₂O₅) additives on the sintering temperature and microwave dielectric properties of (Mg_0.7Zn_0.3)_0.95Co_0.05TiO₃ ceramics were investigated. The (Mg_0.7Zn_0.3)_0.95Co_0.05TiO₃ ceramics were not able to be sintered below 1000 °C. However, when BaCu(B₂O₅) were added, they were sintered below 1000 °C and had the good microwave dielectric properties. It was suggested that a liquid phase with the composition of BaCu(B₂O₅) was formed during the sintering and assisted the densification of the (Mg_0.7Zn_0.3)_0.95Co_0.05TiO₃ ceramics at low temperature. BaCu(B₂O₅) powders were produced and used to reduce the sintering temperature of the (Mg_0.7Zn_0.3)_0.95Co_0.05TiO₃ ceramics. Good microwave dielectric properties of Q × f = 35,000 GHz, ?_r = 18.5.0 and τ_f = −51 ppm/°C were obtained for the (Mg_0.7Zn_0.3)_0.95Co_0.05TiO₃ ceramics containing 7 wt.% mol% BaCu(B₂O₅) sintered at 950 °C for 4 h.     

Sol-gel synthesis of Bi3.25La0.75Ti3O12 nanotubes

Ferroelectric Bi_3.25La_0.75Ti₃O₁₂ (BLT) nanotubes were synthesized by sol-gel technique using nanochannel porous anodic aluminum oxide (AAO) templates, and were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). BLT nanotubes with diameter of around 240 nm and the wall thickness of about 25 nm exhibited a single orthorhombic perovskite structure and highly preferential crystal growth along the [1 1 7] orientation, which have smooth wall morphologies and well-defined diameters corresponding to the diameter of the applied template. The formation mechanism of BLT nanotubes was discussed.     

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.     

FRICTION WELDING OF Zr55Al10Ni5Cu30 BULK METALLIC GLASS

采用摩擦焊对Zr₅₅Al₁₀Ni₅Cu₃₀块体金属玻璃进行了焊接, 当焊机主轴转速为4.0×10³---5.0×10³ r/min, 摩擦压力为80---100 MPa, 摩擦时间为0.2---0.4 s, 顶锻压力和保压时间分别为200 MPa和2 s时, 能够成功实施Zr₅₅Al₁₀Ni₅Cu₃₀金属玻璃的焊接. 用SEM, XRD和TEM观察分析未检测到晶化相, 焊缝处金属仍保持非晶状态. 金属玻璃的塑性在玻璃转变点T_g附近随温度变化很大, 在T_g以上具有良好的塑性变形能力, 这是实施摩擦焊焊接的重要基础.     

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。     

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。     

二维ZnO/ Bi3.9Zn0.4V1.7O10.5纳米异质结构的制备及其可见光催化活性

表面建造是提高半导体光催化活性的一种有效方法。本文利用Zn5(CO3)2(OH)6纳米片为基底沉积了BiVO4再通过煅烧成功制备了二维ZnO/Bi3.9Zn0.4V1.7O10.5复合纳米片。通过X射线衍射,透射电镜和元素映像技术表征了所制样品。结果显示随着锌与铋的原子比的上升,ZnO多孔片状的表面逐渐变成Bi3.9Zn0.4V1.7O10.5物质。但其比例高于1:0.02时,在片状Bi3.9Zn0.4V1.7O10.5的区域表面又生长出BiVO4纳米颗粒。漫反射光谱测试显示出ZnO/Bi3.9Zn0.4V1.7O10.5复合物随着锌与铋的原子比的上升其在400~600 nm可见光区的吸收逐渐增强。所制样品在可见光（波长大于420 nm）进行了光催化降解罗丹明B的测试,结果表明在所制样品中,锌与铋的原子比为1:0.0133的ZnO/Bi3.9Zn0.4V1.7O10.5纳米片虽然其可见光的吸收并没有明显增强但却表现出最佳的光催化活性。荧光与电化学测试得出了低含量BZVO的ZnO纳米片可见光催化活性的提高主要是因为表面ZnO/Bi3.9Zn0.4V1.7O10.5异质结构提高了光生载流子的分离与传送。这种二维材料的表面建造有利于光催化的进行。因此,此法可应用于其它二维纳米材料的建造以提高光催化活性。     

Synthesis and characterization of Y3Al5O12 and ZrO2-Y2O3 thermal barrier coatings by combustion spray pyrolysis

Y₃Al₅O₁₂ and ZrO₂-Y₂O₃ (8 mol% YSZ) coatings for potential application as thermal barrier coatings were prepared by combustion spray pyrolysis. Thermal cycling of as deposited coatings on stainless steel and FeCrAlY bond coat substrates was carried out at 1000 °C and 1200 °C to determine the thermal fatigue response. Structural and morphological studies on Y₃Al₅O₁₂ and 8 mol% YSZ coatings before and after thermal cycling have been carried out. It has been noted that the coatings on FeCrAlY substrates remain intact after 50 cycles between room temperature and 1200 °C, whereas the coatings on stainless steel show some minor damage such as peeling off near the periphery after 50 cycles at 1000 °C. Thermal diffusivity values of Y₃Al₅O₁₂ and 8 mol% YSZ films were measured by using photo thermal deflection spectroscopy and the values are lower than those of coatings produced by conventional techniques such as EBPVD and APS.