Ba掺杂对Pb(Zr,Ti,Sb)O_3压电陶瓷Curie温度与压电性能的影响

用传统固相法制备了组成为0.98Pb1.0–xBaxTi0.48Zr0.52O3–0.02PbSbO3(x=0.18～0.24)的Ba掺杂Pb(Zr,Ti,Sb)O3(PSZT)压电陶瓷。通过X射线衍射和Raman光谱研究了Ba掺杂PSZT陶瓷的结构,并测量和分析了Ba掺杂对PSZT压电陶瓷的Curie温度和压电性能的影响。结果表明:Ba掺杂影响PSZT陶瓷中四方相和三方相的转化过程、两相比例、晶粒大小并导致四方相的晶格畸变。随Ba含量(x)从0.18增加到0.24,PSZT陶瓷的Curie温度从189℃几乎线性下降到141℃;当Ba掺杂量为0.22时,PSZT陶瓷的Curie温度为156℃,压电应变常数d33为578pC/N,机电耦合系数Kp为0.63,机械品质因数Qm为37.3。     

磨辊堆焊材料C-Cr-Si-Mn合金体系中合金成分对使用性能的影响

为研究C-Cr-Si-Mn合金体系堆焊层的耐磨性和磨辊抗剥离能力,进行了不同合金堆焊材料的耐磨性(即磨痕深度)和抗剥离能力的试验。结果表明,(1)合金元素C、Cr含量对堆焊层的耐磨性及抗剥离能力影响大(;2)C-Cr-Si-Mn合金体系的合金元素最佳范围为:w(C)=5.0%～5.5%,w(Cr)=23.5%～29%,w(Mn)3.0%,w(Si)1.5%(;3)工艺对堆焊层的耐磨性及抗剥离性有影响,堆焊修复时需要选择合适的焊接工艺。     

HPLC-UV同时测定皮革中三种含氯苯酚

建立并验证了用HPLC-UV测定皮革中含氯苯酚的方法;以丙酮为溶剂,采用超声波提取法提取皮革中含氯苯酚,以相对保留时间定性,峰面积进行定量;该方法平均回收率为97.20%~103.11%,RSD为1.094%~1.377%,检测限(S/N=3)分别为2,3,5,6-四氯苯酚:0.014 mg/L,五氯苯酚:0.002 mg/L,2,4,6-三氯苯酚:0.004 mg/L;本方法具有方便快捷、灵敏度高、回收率高、精密度好的特点,且避免了大量化学试剂的使用,减少了环境污染。     

轴向柱塞泵关键摩擦副材料匹配的磨损实验研究

论文选用38Cr Mo Al A和LZQT500-7作为轴向柱塞泵关键摩擦副配对材料,然后分五组,对两种材料进行不同的表面处理,对五组试样进行摩擦磨损实验,最后得出38Cr Mo Al A采用氮化＋等离子喷涂二硫化钼、LZQT500-7采用氮化的配对处理工艺是最好的方式。     

The effect of SnO2 on enhancing electrocatalytic property of palladium toward formic acid oxidation

Although palladium (Pd) based materials are considered the best catalyst for formic acid oxidation reaction (FAOR), they are still confronted with a lot of barriers, such as the growth/sintering of Pd nanoparticles (NPs) and the accumulation of adsorbed poisoning intermediates. Herein, tin dioxide (SnO₂) decorated carbon black was utilized as the catalyst carrier to synthesize Pd/SnO₂/C for FAOR. The introduction of SnO₂ significantly reduced the particle size of Pd NPs and forming the Pd–O–Sn structure. Compared with Pd/C, Pd/SnO₂/C owned higher concentration of O_ads and less adsorption amount of poisoning intermediates. The oxygen atoms adsorbed on Pd surface were rapidly transferred to SnO₂ due to the spillover effect. The FAOR reaction kinetic results showed that the introduction of SnO₂ accelerated the diffusion rate of formic acid on the electrode surface. Pd/SnO₂/C exhibited high specific activity (5.97 mA cm⁻²), excellent durability, and high anti-CO poisoning ability toward FAOR due to the introduction of SnO₂.     

Nanofiber-based Sm0.5Sr0.5Co0.2Fe0.8O3-δ/N-MWCNT composites as an efficient bifunctional electrocatalyst towards OER/ORR

It is of significance to search non-noble metal OER/ORR catalysts with perfect performance. The introduction of carbon into perovskite can significantly enhance oxygen electrocatalytic activity. Herein, nanofiber-based Sm_0.5Sr_0.5Co_0.2Fe_0.8O_3-δ/rGO (SSCF28/rGO) and Sm_0.5Sr_0.5Co_0.2Fe_0.8O_3-δ/N-MWCNT (SSCF28/N-MWCNT) hybrids with various mass ratios were synthesized successfully by a facile ultrasonic mixing method and their oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) properties were compared and studied. In 0.1 M KOH, SSCF28/N-MWCNT = 1.3 with optimal mass ratio shows better OER/OER bifuntional catalytic activity than SSCF28/rGO = 2:1. After 1000 CV cycles, SSCF28/N-MWCNT = 1.3 remains stable. Compared to SSCF28/rGO = 2:1, SSCF28/N-MWCNT = 1:3 shows promising practical applicability in metal-air batteries. The excellent OER/ORR activity of SSCF28/N-MWCNT = 1:3 can be attributed to the component optimization of perovskite and carbon and the synergistic effect between nanofiber-structured SSCF28 and N-functionalized MWCNT (N-MWCNT).     

Accelerated transfer and separation of charge carriers during the photocatalytic production of hydrogen over Au/ZrO2–TiO2 structures by interfacial energy states

Energy states and surface plasmon resonance (SPR) play an important role in photocatalytic processes and power generation energy, for they improve the separation, transport, and mobility of charge carriers. The creation of Au/semiconductor heterostructures with different amounts of Au forms energy states that can modulate surface plasmon excitation, interfacial charge transport and photocatalytic activity to generate hydrogen. However, the Au loading effect on the interfacial charge transport and photocatalysis of plasmonic Au/semiconductors is unclear. For this reason, in this study, Au/ZrO₂–TiO₂ materials with different Au loadings were synthesized and evaluated in the photocatalytic production of hydrogen. The results confirmed boosted photoactivity with increased gold loading up to 5 wt.%, obtaining four times more hydrogen production than with the base material. The (photo) electrochemical measurements revealed that the Au inclusion provoked the adjustment of Fermi level values associated with the variation of surface energy states at the Au/ZrO₂–TiO₂ interface, which can be related to the modulation of SPR. This phenomenon can be explained by two simultaneous effects: i) the creation of energy states at the Au/ZrO₂–TiO₂ interface that modify the Fermi level to more negative potentials with respect to the base material, in order to have photogenerated electrons with higher reducing power to catalyze the hydrogen production; and ii) the Au metallic nanoparticles with SPR act as electronic reservoirs that extend the life time of photogenerated electron-hole pairs, thus enhancing the separation of charge carriers and the mobility of photogenerated electrons.     

基于VMD的Volterra模型奇异值熵的转子故障诊断方法

针对转子故障信号的非平稳性以及敏感故障特征无法有效提取的问题,将变分模态分解(variational mode decomposition,VMD)的Volterra模型和奇异值熵相结合,提出一种故障诊断方法。对影响VMD分解准确性的参数选取方法进行了深入研究,给出了相关问题的解决策略。首先,对不同工况下转子实测信号进行VMD分解,利用能量熵增量选取对故障特征敏感的固有模态函数(intrinsic mode function,IMF)进行相空间重构,以建立Volterra自适应预测模型,将模型参数作为初始特征向量矩阵。然后,对初始特征向量进行奇异值分解以获取奇异值熵和奇异值特征向量矩阵,用于描述转子的故障特征。最后,采用模糊C均值(fuzzy c-means,FCM)算法对转子工作状态和故障类型进行识别。试验结果表明,所提方法可有效实现转子故障的特征提取及类型识别。通过同经集合经验模态分解(ensemble empirical mode decomposition,EEMD)相比,证明了该方法具有更有效的故障特征提取性能,是一种可行的方法。     

舒展原理及应用

在一个完美的生产过程中，很少会需要舒展，纸幅会保持均匀平直。现实情况非常不同，绝大多数的成幅材料在处理过程中需要舒展，以防止或去除折皱，扩展幅面或在复卷分切过程中分开。成形网和干网的舒展是属于较少的无端材料的舒展情况。笔者在工作过程中发现国内纸厂的工程师和纸机操作人员普遍对它的机理不太了解甚至误解，这样不利于它的选型、操作和维护。因此基于工作的便利组织了此文。本文旨在介绍相关知识，启发思维，提高生产力。     

合理改进压力筛内部结构,提升设备运行效率

昆山钞票纸厂抄二车间有3台20世纪50~60年代从法国进口的压力筛,由于设备运行时间久远,其使用效率已逐渐降低,故障发生率较高,基本上1~2个月需维修1次。压力筛发生的故障主要是顶部的密封不好,导致漏水漏浆进而影响顶部轴承的使用寿命;其次是底部轴承经常性损坏。经过对故障产生原因的分析,对这2部分结构进行了技术改造,改造后的压力筛运行周期明显延长,一年只维修1~2次,大大提高我厂生产效率。