温度梯度下XLPE同轴和平板结构试样空间电荷行为对比性研究

直流电场下,电缆绝缘中的温度梯度效应导致绝缘材料空间电荷行为复杂,影响电缆系统长期运行的可靠性.目前,温度梯度下电缆绝缘空间电荷特性的研究多集中于平板结构的切片试样,但平板结构切片试样的空间电荷测量能否反映真实电缆绝缘中的空间电荷特性尚缺乏有力证明.该研究测量并分析了温度梯度场下2种不同结构(同轴结构、平板结构)10 kV交联聚乙烯(cross-linked polyethylene,XLPE)试样的空间电荷演变特性以及电场分布行为,基于去压状态下的空间电荷行为,计算了XLPE同轴电缆和切片试样的载流子迁移率以及陷阱深度分布,并对2种结构XLPE试样的空间电荷行为和电荷特性参数进行了对比性研究.该研究结果表明同轴结构和温度梯度效应均会加剧XLPE电缆外半导电层附近的空间电荷积聚,除了结构因素的影响,温度梯度场下XLPE同轴电缆和平板切片试样的空间电荷演变规律以及电荷特性参数均呈现出等效规律.     

船舶钢板激光弯曲成形的实验研究

在对船舶钢板激光弯曲成形过程进行实验研究中，采用CO2激光器研究了激光功率、扫描速度、扫描次数以及钢板厚度对船舶钢板激光弯曲成形的影响规律。实验中实时测量了船舶钢板激光弯曲成形过程钢板弯曲角度和温度的变化。结果表明：钢板弯曲角度随激光功率的增加而增加，随激光束扫描速度的增加而减小，而且随着钢板厚度的增加，弯曲角度减小；激光工艺参数和钢板厚度都对钢板激光多次扫描成形产生影响，钢板的弯曲角度随着激光扫描次数的增加而增加。对于较薄的船舶钢板，钢板弯曲角度随扫描次数增加近似呈线性增加，而较厚的钢板，随扫描次数的增加，钢板弯曲角度的增加逐渐减小。     

Evaluation of the superplastic formability of SP-inconel 718 superalloy

The superplastic formability of SP- lnconel 718 superalloy was evaluated using the argon blowing method. Relationships among superplastic forming parameters (forming temperature, argon pressure, and forming time) and specific dome height (dome height/workpiece diameter) were investigated, as were changes in material properties after superplastic forming. Experimental results showed the optimum forming temperature range for SP- lnconel 718 to be between 975 and 995 °C. During the superplastic forming process, 5- phase precipitates formed at grain boundaries and limited the grain growth, which is considered beneficial for superplastic deformation. On the other hand, increasing the forming deformation also increased the formation of cavities, which can be attributed to the existence of niobium- rich inclusions. This degraded the superplasticity of the superalloy. Electrochemical tests showed that the corrosion resistance of SP- lnconel 718 after superplastic forming worsened because of the existence of both S- phase precipitates and niobium- rich inclusions.     

Effects of phosphorus addition on the magnetic properties of sintered Fe-50 wt.% Ni alloys

Phosphorus was added to Fe-50 wt.% Ni in the form of a coated composite powder via an electroless plating process. Addition of phosphorus to Fe-50 wt.% Ni facilitated increases in density and grain size, both of which were beneficial to magnetic performance. Because of the homogeneous distribution of phosphorus in the powder, the optimal phosphorus addition was much lower than for those using Fe₃P as the phosphorus precursor. The optimal phosphorus addition was close to its maximum solubility in Fe-50 wt.% Ni (about 0.5 wt.%), above which precipitation of excessive phosphorus in the form of iron nickel phosphide, (Fe,Ni)₃P, effectively degraded the magnetic properties of Fe-50 wt.% Ni. Without the addition of phosphorus, good magnetic properties could be achieved only when the sintering temperature was high enough (>1200 °C) to result in a high sintered density and large grains in the sintered structure.     

铝元素的添加对锆基合金非晶形成能力影响的电子结构模型

通过构建非晶合金的团簇模型，利用离散变分法从电子层次研究了Al元素对Zr-Cu非晶合金中团簇稳定性的影响。结果表明，Al原子的引入提高了团簇中原子间的亲和力，并且随着Al原子数的增加，亲和力增大，导致新的团簇产生，从而破坏了非晶的团簇结构，Al含量对Zr-Al-Ni非晶合金的稳定性的影响可通过Fermi能级处的态密度大小来反映。     

Densification and Phase Development of Spodumene–Cordierite Glass Powder Mixtures

The sintering and crystallization of spodumene-cordierite glass-ceramics that are made from mixtures of Li₂O-Al₂O₃-SiO₂ (LAS) and MgO-Al₂O₃-SiO₂(MAS) glass powders were investigated. Pure LAS and MAS powders have good sinterability. However, the densification of LAS was drastically reduced when small amounts of MAS were added. When larger amounts of MAS were added, the amount of densification further increased. The decrease in the Li₂O content in the LAS glass promoted the densification of the mixed glass samples. The above-mentioned results can be explained by examining the crystallization temperature, which is influenced by the interactions between the LAS and MAS glass particles. The lower the temperature of crystallization, the less sintering occurred. For the sintered samples, the phase that crystallized from the MAS glass was alpha-cordierite, and that which crystallized from the LAS glass was ß-spodumene or high-quartz solid solution, depending on the Li₂O content in the LAS glass.     

电容式土壤水分传感器的电导变异性试验研究

为评估电容式土壤水分传感器受土壤电导率的影响及其对农田土壤电导率变化范围的适用性,配制了一系列土壤等效含水率为40.6%、电导率为0~1.91dS/m的土壤等效介电溶液,分别对激励信号频率为40,50,60,70,80,90,100MHz的7种传感器进行了电导变异性试验,并且配制了相同含水率但电导率分别为0,0.31,0.46和0.61dS/m的4种土样进行了验证试验。试验结果表明:1)土样中的测试结果基本上与介电溶液吻合,可采用等效介电溶液评估传感器的电导变异性;2)传感器的电导变异率随待测介质电导率的升高而近似线性增大,相同电导率下,传感器激励信号频率越高其电导变异率越小;3)在农田土壤电导率基本变化区域0.239~0.650 dS/m内,当传感器激励信号频率从不低于80MHz时,其最大电导变异率为9.2%,能满足工程上的实际应用要求。     

锐钛型TiO2对尿素热解过程的影响

通过实验的方法收集了不同温度下纯尿素和尿素/TiO₂混合物热解后的固体残留物，使用红外光谱（IR）及气相色谱质谱联机（GC-MS）方法对这些热解残留物进行成分分析；使用热重-红外联机（TG-FTIR）技术研究尿素及三聚氰酸在有无催化剂TiO₂的情况下的热解特性及气体产物的生成规律；根据Coats-Renfern方法对尿素热解第一阶段的非等温热失重率曲线的数据进行动力学研究，建立动力学方程。结果表明，100~250℃的尿素热解残留物中主要为尿素和缩二脲，300~400℃的尿素热解残留物中主要为三聚氰酸等含氮杂环有机化合物；锐钛型TiO₂能促进尿素和三聚氰酸的热解反应，缩短其反应进程，HNCO与水蒸气在TiO₂表面易发生反应；尿素第一阶段热解的反应级数为2，单独热解时活化能为113.25kJ/mol，指前因子A为2.01×10¹¹min^-1，在催化剂TiO₂的作用下，活化能E为77.42kJ/mol，指前因子A为4.82×10⁷min^-1。     

Evaluation of wastewater reclamation processes in a high-tech industrial park

The objectives of this research were to evaluate two different processes using for wastewater reclamation in a hightech industrial park area in Taiwan. The major units of the first AC-RO-IE system included sand filter, an activated carbon (AC) bed, microfiltration module, a reverse osmosis (RO) membrane and ionic-exchange (IE) columns. The second DAF-AC-RO system was comprised of coagulation/flocculation, dissolved air flotation (DAF), an activated carbon bed, microfiltration module and reverse osmosis membrane units. This study was carried out at a pilot-scale plant in situ that operated for approximately 1 year. According to the long-term experimental results, both the AC-RO-IE and the DAF-AC-RO processes illustrated excellent performances on inorganic and organic contaminant removal. Comparing the removal efficiency of the filtration-AC units in the AC-RO-IE system with the coagulation-DAF-AC units in the DAF-AC-RO system, the removal efficiency of TDS, SiO₂ and COD increased by 19.8%, 70.1% and 44.4% in the latter system, respectively. In addition, the combination of PAC-coagulation and DAF units could improve hardness removal, modify the form of dissolved silica, and reduce the SDI and MFI values. It showed good potential as a pretreatment unit in wastewater reclamation processes. Therefore, based on the reclaimed wastewater quality and process operational stability, the DAF-AC-RO system was suggested as a potential process for further application.     

石墨粉镀银新工艺研究

研究了镀液中硝酸银浓度、石墨粉加入量和阴极电流密度等工艺条件对镀银石墨粉含银量和电镀效果的影响。用扫描电镜对镀银石墨粉的微观形貌和镀覆效果进行分析，通过X射线衍射仪对镀银石墨粉高温灼烧后的剩余物进行分析测试并计算镀银石墨粉的含银量。研究结果表明：采用惰性电极作为电镀阳极，在化学镀预处理过的石墨粉表面可成功镀覆一层银，其含银量达76%。