Hydrothermal Synthesis of Acicular Lead Titanate Fine Powders

A pure, acicular lead titanate (PbTiO₃) fine powder with a white color has been prepared by hydrothermal synthesis. It is a new phase of PbTiO₃ with I 4 symmetry, cell parameters of a = 12.358 Å and b = 14.541 Å, and a density of 6.80 g.cm⁻³. The influences of pH (12.5 to 14.4), Pb/Ti ratio (1.0 to 1.6) in the feedstock, reaction temperature (130° to 230°C), time (0.25 to 4 h), starting materials, and additives on the formation of acicular PbTiO₃ under hydrothermal conditions have been investigated. The acicular PbTiO₃ with I 4 symmetry, referred to as the PX phase, can be converted to the perovskite-type (PE phase) of PbTiO₃ at about 605°C while its acicular morphology is essentially unchanged. The preferable conditions for preparing pure acicular PX-phase PbTiO₃ are that the pH is 13.0 to 14.0, Pb/Ti ratio is >1.3, reaction temperature is 170° to 200°C, time is 0.5 to 1.0 h, titanium butoxide (Ti[O(CH₂)₃CH₃]₄) is the starting material, and poly(vinyl alcohol) is an additive. The acicular grain of the PX phase is usually less than 100 nm in diameter and more than 1000 nm in length.     

Antiferroelectric lead zirconate thin films derived from acetate precursors

Antiferroelectric lead zirconate (PbZrO₃) films derived from acetate precursors have been fabricated on Pt/Ti-coated silicon wafers and fused silica at 700 °C with an automatic dip-coating process. Films formed directly on the metallized silicon wafer showed the coexistence of perovskite and pyrochlore phases. A pre-coated titania layer of about 10 nm facilitated the formation of the desired perovskite phase. Films deposited on fused silica exhibited interactions between lead and silica which inhibited the crystallization of the films. In this case, a pre-coated titania layer in the range 50–75 nm acted as a diffusion barrier layer, allowing the formation of the perovskite phase. Antiferroelectricity in the films was confirmed by X-ray superstructure, dielectric double hysteresis loops and d.c. bias behaviour at room temperature. The corresponding transverse electro-optic properties were also measured for films deposited on fused silica.     

无约束淬火机目标温度神经网络预报

淬火、控制冷却的冷却速度和目标温度是关系到钢板性能的关键因素 ,但由于冷却过程的水量、水温、辊道速度等对冷却目标温度的影响属多变量非线性过程 ,用简单的解析模型通常精度较低 ,难以达到精确控制的要求。采用人工神经网络技术对无约束淬火机目标温度进行快速预报 ,结果表明 ,预测精度高 ,快速准确     

催柴加氢装置分馏系统空冷改造方案的探讨

对催柴加氢装置分馏系统空冷存在的问题进行了剖析,认为两塔回流温度不能同时满足工艺需要的主要原因是2台空冷共用风机造成的,并对改造方案进行了比较。     

一种新型同位素示踪剂载体及应用

同位素沾污、低注井同位素示踪剂因沉降造成的上返速度慢或无法上返、大孔道地层同位素示踪剂失踪等是影响注水开发油田后期吸水剖面测井资料质量的主要问题。同位素示踪剂载体的物理参数，尤其是其密度，是产生上述问题的重要因素。通过对同位素示踪剂载体技术指标优选而生产的一种新型同位素示踪剂，可以解决低注井同位素上返速度慢的问题，并能有效识别大孔道地层，减少同位素沾污。这种同位素示踪剂载体已在河南油田吸水剖面测井中应用，并见到了很好的效果。     

旧工业建筑的再利用

旧工业建筑与其他旧建筑物相比,具有建筑主体结构坚固,空间高大灵活;体量大,拆除或新建对环境造成的影响大;具有其独特的设计理念和美学价值等特点,从而成为旧建筑再利用过程中一种重要的建筑类型。 本文通过对101厂房再利用案例设计过程的分析,对旧工业建筑再利用的目标、更新程序、方式、策略等方面进行具有可操作性和推广性的探索。     

风冷冷水机组室内安装方案的探讨

结合实际工程，介绍风冷冷水机组在工程应用中置于建筑转换层或建筑内的设计，并对风冷冷水机组室内安装的设计进行探讨。     

振动采油工艺在稠油区的实验研究与应用

在天然地震的影响下,油井产量发生波动,使人们受到启示,从而引进了振动采油工艺技术。本文对振动增产的机理进行了探讨,指出振动增油机理在于加快地层中流体的流速;改变储集层内油、气、水的重新分布;改变岩石表面润湿性,有利于清除油层堵塞,提高渗透率。通过分析两个试验区的振动采油效果,总结出在不同扰动力、不同激振频率、不同振动周期下的增产效果和规律,对振动采油的实施具有一定的指导意义。     

调整煤源结构优化炼焦煤质量管理

介绍了湘钢在调整煤源结构、优化炼焦煤质量管理方面所做的一些工作。近年来 ,湘钢依靠科技进步 ,坚持精料方针 ,不断强化企业管理 ,使焦炭质量有了较大的提高 ,为降低高炉焦比 ,提高高炉的利用系数做出了应有的贡献