Effect of Nb2O5 content and sintering temperature on the microstructure and bending strength of porous Ni-YSZ cermets

Porous Ni-YSZ cermets are prepared by reducing NiO-YSZ composites upon exposure to (Ar+6% H₂) gas. The porous cermets are prepared by the addition of carbon black (0.123 mol) to mixed NiO-YSZ powders and the conversion of NiO to Ni in the NiO-YSZ composites. The microstructure and bending strength of porous Ni-YSZ cermets as functions of sintering temperature and Nb₂O₅ content are discussed. The Ni-YSZ cermets consist of uniformly distributed Ni and YSZ grains as well as pores. Both higher sintering temperature and higher Nb₂O₅ content yield lower porosity, thus increasing the bending strength. The bending strength of 0.00470 mol% Nb₂O₅–containing Ni-YSZ cermets sintered at 1400 °C (111 MPa) is about two times higher than that of Nb₂O₅–free Ni-YSZ cermets sintered at 1400 °C (59 MPa).     

Synthesis and luminescence properties of CeF3：Tb3＋ nanodisks via ultrasound assisted ionic liquid method

CeF3 and CeF3：Tb3＋ nanocrystals were successfully synthesized by the ultrasound assisted ionic liquid （IL） method at room temperature. X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, selected area electron diffraction （SAED）, high-resolution transmission electron micrographs （HRTEM） and photoluminescence （PL） spectra were employed to characterize the nanocrystals. The results of XRD indicated that the obtained samples crystallized well with a hexagonal phase crystal structure. SEM and TEM images demonstrated that the obtained CeF3：Tb3＋ nanocrystals had a discoid shapein the presence of ultrasound and IL, whereas only granular nanoparticles were obtained by magnetic stirring. The possible formation mechanisms of the crystal growth were proposed. The PL spectra of the CeF3：Tb3＋ nanodisks exhibited a strong green emission when excited at 254 nm. Furthermore, the photoluminescence intensity of CeF3：Tb3＋ of the discoid particles was largely improved com-pared with that of the granular nanoparticles.     

Study on the gaseous and electrochemical hydrogen storage properties of as-milled CeMgNi-based alloys

For gaining further insight into the involvement of the gaseous and electrochemical hydrogen storage properties of CeMg₁₂-type alloys, partial substitution and ball milling were both used to synthesize the nanocrystalline and amorphous CeMg₁₁Ni + x wt.% Ni (x = 100, 200) samples. This research aims at elucidating the functional roles of Ni content and milling time on samples' structure and hydrogen storage performance. X-Ray diffraction and high-resolution transmission electron microscope were used to reveal the micro constructions of alloys. To determine the gaseous hydrogen storage property, Sievert's apparatus and a thermal gravity analysis bonded with a H₂ probe were adopted. The dehydrogenation activation energy was computed in the Kissinger method. The electrochemical performances of the as-milled samples were measured through a constant current system. Further researches showed that the electrochemical performance of as-milled samples had been dramatically improved by increasing Ni content. With milling duration lengthens, the gaseous hydrogen absorption capacity, gaseous hydriding rate and high rate discharge capability of samples reached the maximal values, but electrochemical discharge capacity and gaseous dehydriding rate always increased. The dehydrogenation activation energy decrease resulted by improving Ni percent and milling duration was deemed as the cause of the excellent gaseous kinetics of samples.     

Poly(N-vinyl-2-pyrrolidone)-stabilized ruthenium supported on bamboo leaf-derived porous carbon for NH3BH3 hydrolysis

In this work, poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium nanoparticles (NPs) supported on bamboo leaf-derived porous carbon (Ru/BC) has been synthesized via a one-step procedure. The structure and morphology of the as-synthesized samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). As a catalyst for hydrogen generation from the hydrolysis of ammonia-borane (AB, NH₃BH₃) at room temperature, Ru/BC stabilized with 1 mg of PVP exhibited high activity (TOF = 718 mol_H2·mol_Ru⁻¹·min⁻¹) and low activation energy (E_a = 22.8 kJ mol⁻¹). In addition, the catalyst could be easily recovered and showed fairly good recyclability with 55.6% of the initial catalytic activity retained after ten experimental cycles, which confirmed that PVP could stabilize the Ru NPs and prevent their agglomeration on BC surface. Our results suggest that PVP-stabilized Ru/BC is a highly efficient catalyst for the hydrolysis of AB.     

A simple non-destructive method to indicate the spallation and damage degree of the double-ceramic-layer thermal barrier coating of La2(Zr0.7Ce0.3)2O7 and 8YSZ:Eu

Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La₂(Zr_0.7Ce_0.3)₂O₇ (LZ7C3) and Eu³⁺-doped zirconia, which was partially stabilised by 8 wt% yttria (8YSZ:Eu), were prepared by atmospheric plasma spraying. A thermal cycling test was carried out. The 8YSZ:Eu sublayer exposed during thermal cycling could produce visible luminescence under ultraviolet (UV) illumination, providing an indication of the spallation and damage degree of the coating. The result shows that the application of a Eu³⁺-doped luminescence sublayer can be a very simple and useful non-destructive technique to indicate the spallation and damage degree of DCL coatings.     

A new partially-gelatinized granular starch prepared by industry-scale microfluidization treatment of pea starch

Pea starch was subjected to industry-scale microfluidization (ISM) treatment at selected pressures (30, 60, 90 and 120 MPa) for one pass, and changes in structure were studied by the analysis of morphology, granule size, damaged starch, internal ordered structure and thermal properties. Also, pasting and rheological properties of ISM-treated PeaS were investigated. ISM treatment caused starch granules swell to a larger size, but retained the granular integrity. In combination with the disrupted long-range crystalline, the disturbed short-range ordered structure and the reduced gelatinization enthalpy of pea starch, it was inferred that ISM-treated PeaS was analogue to partially-gelatinized granular starch. RVA determination indicated that pasting viscosity of ISM-treated PeaS was enhanced, which was attributed to the loosened internal structure of intact granular starch. Viscoelastic modulus and tan δ value of ISM-treated PeaS were respectively increased and diminished, and the extreme values were obtained for ISM-60 PeaS. Additionally, ISM-treated PeaS behaved lower in-shear recovery values, which may be the reason that the reinforced gel network structure of ISM-treated PeaS was more difficult to recover their original state. Considering the simple operation and efficient modification of this technique, ISM could be a good option to applied in producing partially-gelatinized granular pea starch for industrial applications.     

1,3,5-苯三甲酸衍生物类新型成核剂的合成及应用研究

合成了新型成核剂1,3,5-苯三甲酸三（环己胺）（BTCA-TCHA）,研究了该成核剂对等规聚丙烯力学性能、结晶行为和熔融行为的影响。结果表明,成核剂BTCA-TCHA可明显改善等规聚丙烯的力学性能和光学性能,并可以大幅度提高结晶峰温度。当BTCA-TCHA添加量为0.2 %时,等规聚丙烯的拉伸强度和弯曲模量可分别提高9.72 %和12.4 %,雾度降低53.5 %。当降温速率为20 ℃/min时,添加BTCA-TCHA的等规聚丙烯的结晶峰温度可从空白样的114.6 ℃提高到126.8 ℃。BTCA-TCHA的性能与传统的山梨醇类成核剂Millad 3988基本接近。     

含导电聚苯胺类锂离子电池复合材料的现状及发展趋势

导电聚苯胺（PANI）是近十年来研究最多的导电聚合物,具有比容量高、氧化还原可逆性好、电导率高、合成方法简单、成本低等特点,在化学电源和超级电容器中的应用最为广泛。导电聚苯胺复合材料的合成方法主要分为：原位复合法、共混法、自组装和电化学复合法等。导电聚苯胺复合材料可作为高能物质用于研发电极材料,但目前利用导电聚苯胺对锂离子电池三元正极材料进行修饰改性的研究较少。综述了导电聚苯胺及其复合材料的热电化学性能,重点对导电聚苯胺/锂离子电池复合正极材料的性能进行了阐述。最后对导电聚苯胺复合材料的应用和研究方向进行了总结,并简述了导电聚苯胺包覆改性LiNi_1-x-yCo_xMn_yO₂复合材料的应用和展望。     

香叶循环煮制对肉汤挥发性风味的影响研究

采用感官评价、电子鼻和气相质谱联用仪(gas chromatography-mass spectrometry,GC-MS)研究香叶循环煮制过程(5次)对猪里脊肉汤挥发性风味的影响。感官评价结果发现煮制1、2、3次的样品香气之间存在明显差异,煮制3、4、5次样品间香气无明显差异。电子鼻结果表明煮制2、3、4次的样品可能具有相似的气味轮廓。GC-MS测出香叶组肉汤中共有45种挥发性化合物,相对于空白组,主要增加的化合物有桉油醇、(-)-4-萜品醇、α-松油醇、桉油烯醇、雪松醇、丁香油酚、4,6-二叔丁基间甲酚、乙酸松油酯等。煮制1次时,香叶组肉汤中挥发性化合物种类和总含量最多,且均随煮制次数的增加而减少。醇类、醚类、酚类、酯类四类化合物在煮制2次后含量骤减。综合分析,肉汤样品中挥发性风味成分的增加多源于香叶的直接引入,且在煮制2次后,肉汤整体气味轮廓和挥发性化合物的种类及含量均变化较大,在第2次循环时香叶的补充量约为初始量的63%,第3次循环时补充量约为初始量的72%。