添加型防静电涂料的研究进展

对添加型防静电涂料的组成、导电机理、导电填料的研究状况进行了综述,重点论述了导电填料的研究重点和发展方向.白色和浅色导电填料是未来添加型防静电涂料的重点研究对象.     

惰性气体中电爆丝爆炸激励冲击波的理论分析

建立了惰性气体中电爆丝爆炸激励的冲击波模型。对于冲击波马赫数与光辐射强度的关系、惰性气体种类对冲击波强度的影响以及电爆丝根数对冲击波强度的影响,进行了理论计算与分析,所得结论对红外脉冲强光辐射源的研究有重要作用。     

惰性填料对SiCf/Si-O-C陶瓷材料的性能影响

以聚硅氧烷为先驱体,采用先驱体转化法制备了SiCf/S i-O-C陶瓷复合材料.研究了惰性填料(SiC、SiO2及SiO2空心微珠)对材料的力学性能及热性能的影响.微观结构的分析表明,填料引起的界面结构与密度的变化是影响SiCf /Si-O-C复合材料性能的主要原因.     

油罐惰化置换时间的数学计算与模拟实验

基于对油罐惰化置换过程的假设和简化,得到惰化置换时间的计算公式,然后通过对计算公式的修正,完成了对油罐惰化置换时间的计算。最后通过对3次不同流量条件下模拟实验数据的非线性拟合,分别计算出3次实验气体扩散系数的取值,得到O2体积分数与置换时间之间的完整表达式。数学计算和实验的方法与结论将为进一步研究油罐油气的惰化置换规律提供有价值的参考。     

活性填料在聚碳硅烷先驱体转化陶瓷中的应用

比较了铝 (Al)、铬 (Cr)、二氢化钛 (TiH2 )和锆 (Zr)等活性填料在聚碳硅烷 (PCS)先驱体转化陶瓷中的应用。研究表明 ,在先驱体中加入活性填料能有效降低陶瓷素坯的气孔率 ,可与PCS气态裂解产物、游离碳和 (或 )N2 气氛反应生成新的化合物 ,提高PCS的陶瓷产率。活性填料的种类与含量对陶瓷烧成体的线收缩有较大的影响 ,Al、Cr能抑制烧成体的线收缩 ,其含量越高 ,线收缩越小。但是TiH2和Zr并不能抑制陶瓷烧成体的线收缩 ,其含量越高 ,线收缩越大。此外 ,活性填料的种类及含量对陶瓷烧成体的三点弯曲强度也有较大的影响。Al、Zr的含量越高 ,材料的强度也越大。但Cr和TiH2 的加入却使材料强度下降。认为Al是较好的活性填料。用X -衍射法 (XRD)分析了烧成产物的物相组成 ,扫描电子显微镜 (SEM)观察了陶瓷烧成体的断口形貌。     

惰性气体灭火系统减压孔板设计计算方法研究

选择DN40及其三种规格孔径的IG100惰性气体灭火系统减压孔板为研究对象,采用fluent数值计算软件进行计算,得到压比-流量特性曲线及计算公式,在设计计算时可直接根据压比-流量特性曲线选择合理的减压装置,为此类设计提出了一种新的计算研究手段。     

Investigation on the process parameters of TIG-welded aluminum alloy through mechanical and microstructural characterization

Multi-pass TIG welding was conducted on plates (15×300×180 mm3) of aluminum alloy Al-5083 that usually serves as the component material in structural applications such as cryogenics and chemical processing industries. Porosity formation and solidification cracking are the most common defects when TIG welding Al-5083 alloy, which is sensitive to the welding heat input. In the experiment, the heat input was varied from 0.89 kJ/mm to 5 kJ/mm designed by the combination of welding torch travel speed and welding current. Tensile, micro-Vicker hardness and Charpy impact tests were executed to witness the impetus response of heat input on the mechanical properties of the joints. Radiographic inspection was performed to assess the joint's quality and welding defects. The results show that all the specimens displayed inferior mechanical properties as compared to the base alloy. It was established that porosity was progressively abridged by the increase of heat input. The results also clinched that the use of me-dium heat input (1-2 kJ/mm) offered the best mechanical properties by eradicating welding defects, in which only about 18.26% of strength was lost. The yield strength of all the welded specimens remained unaffected indicated no influence of heat input. Partially melted zone (PMZ) width also affected by heat input, which became widened with the increase of heat input. The grain size of PMZ was found to be coarser than the respective grain size in the fusion zone. Charpy impact testing revealed that the absorbed energy by low heat input specimen (welded at high speed) was greater than that of high heat input (welded at low speed) because of low porosity and the formation of equiaxed grains which induce better impact toughness. Cryogenic (-196 C) impact testing was also performed and the results corroborate that impact properties under the cryogenic environment revealed no appreciable change after welding at designated heat input. Finally, Macro and micro fractured surfaces of tensile and impact specimens were analyzed using Stereo and Scanning Electron Microscopy (SEM), which have supported the experimental findings.     

进气口位置和进气体积流量对油罐油气惰化置换效率的影响

采用机械通风方式对油罐油气进行处理,具有安全性差、通风时间长和效率低下的缺点;利用燃惰气对油罐油气进行处理,可较好地克服上述缺点。在前期研究的基础上,设计模拟实验台架,以燃惰气为介质,实验研究进气口位置和进气体积流量对燃惰气惰化置换油罐油气的影响。     

谈英语教学中学生创造思维的培养

目前，我国外语教学普遍存在费时较多、收效较低的现象，特别是精读课教学，向来只注重给学生注入语言知识，而轻视学生创造思维能力的培养。要解决这一问题，外语教学工作者必须改变教学观念，避免在外语课教学中只重识记而轻思维这一现象。     

油罐油气惰化置换过程数值模拟研究

基于对油罐惰气置换原理的分析,建立了油气惰化置换过程的紊流模型,采用压力和速度耦合场的PISO算法,完成了油罐惰气置换过程的数值模拟研究。用原型实验数据对模型进行了验证,经验证对比表明模型与实验结果吻合较好。进一步研究表明,对于3 000 m^3的油罐,约整个置换过程的前9 600 s,罐内气体处于爆炸燃烧范围,置换约9 600 s后油罐已处于安全状态;＂置换死角＂出现在靠近燃惰气进口两侧的中央偏下位置;罐内各气体组分除在靠近燃惰气进口一侧的较小空间内对流扩散速度较大外,其他大部分位置各气体组分对流扩散速度较小。这些结论将为油气惰化置换过程的进一步优化提供一定的参考依据。