三明治型电磁屏蔽功能复合板材的制备及性能研究

以高强涤纶工业丝和不锈钢长丝配伍织制的机织间隔织物为增强体,在间隔织物空间中进行泡沫填充,织物表面进行树脂复合,制备了三明治型功能复合板材。对不锈钢长丝网格配置对板材的电磁屏蔽性能的影响进行了实验分析,并对比分析了不锈钢长丝网格的引入对三明治型复合板材的力学性能的影响。研究表明,面层中添加不锈钢长丝网格后,复合板材具有了电磁屏蔽效能,双面添加不锈钢长丝网格的板材屏蔽效能明显优于只单面添加不锈钢长丝网格的板材,在高频区域屏蔽效能达到了30dB以上。不锈钢网格的添加未对复合板材的整体力学性能造成显著影响。     

不锈钢纤维织物电磁屏蔽效能的研究现状

不锈钢纤维织物具有电磁屏蔽效能良好及防辐射效果持久、透气性好、穿着舒适、加工方便等特点,是当今世界上应用最广泛的高效屏蔽织物.简要描述了不锈钢纤维混纺纱线、不锈钢纤维织物的制备方法及其产品开发现状,重点阐述了不锈钢纤维特性、纱线结构、织物结构及电磁波频率等因素对不锈钢纤维织物电磁屏蔽效能的影响规律.此外,还指出对电磁波屏蔽机理的探索和产品的开发是该材料领域今后的研究重点.     

基于各向异性织物的电磁屏蔽性能仿真计算

为实现电磁织物的屏蔽效能理论预测及其优化设计,本研究对电磁屏蔽织物构建了三维模型,采用CST (Computer simulation technology)微波工作室模拟各向异性织物与电磁波相互作用的机理。计算了在1~18GHz波段内,电磁波入射角和方位角对屏蔽效能的影响。结果表明:x轴和y轴方向介电常数对织物屏蔽效能的影响较为显著,且在各向异性介电常数较小时,屏蔽效能随电磁波入射角的增加呈现先增大后减小的趋势;而当电磁波方位角发生变化时,不同电磁波入射角对其产生的屏蔽效能影响规律不同。本研究结果对各向异性织物具有较好的适用性,为开发高性能电磁屏蔽织物提供理论依据。     

电磁屏蔽织物材料研究进展

目的现代战场电磁环境日益恶化,含有电子元件和电爆装置的高价值、高技术弹药能否在复杂电磁环境中发挥应有效能,已经成为武器装备建设中一个亟须解决的问题。方法利用电磁屏蔽织物材料作为包装内衬或遮蔽篷布,以增强高价值、高技术弹药在复杂电磁环境中的抗电磁干扰能力,对确保弹药的可靠性具有重要意义。结果综述了金属纤维混纺织物、金属化学镀织物、金属真空镀织物和涂层屏蔽织物研究现状,对比分析了各种织物材料制备工艺的优缺点,简要介绍了非晶态合金织物屏蔽效能的研究进展。结论电镀非晶态合金织物是未来电磁屏蔽织物材料发展的重点方向之一。     

非织造基网格型碳纤维复合材料的屏蔽性能分析

在PET非织造基材表面,采用等间距排列连续碳纤维的方式制备网格型单层和双层碳纤维复合材料,测试分析具有不同排列间距、重叠层数和重叠角的复合材料,在30 MHz~1.5GHz频段内的电磁屏蔽性能,从而为制备低成本、高性能的电磁屏蔽复合材料提供一定的理论指导。结果表明:对单层网格型复合材料,在碳纤维排列间距为6mm时,其最优屏蔽效能特征峰值为46.66dB,对应频率1.05GHz;对双层网格型复合材料,以0°-0°角重叠、排列间距为6mm时,其屏蔽效能特征峰值达到51.31dB,对应频率1.15GHz;相比于单层复合材料,双层复合材料的屏蔽性能提高了10%,其有效频宽提高了42%。     

镀银织物双层叠放模式与电磁屏蔽效能增量研究

电磁辐射是四大环境污染之一,通过不同电磁屏蔽体的叠加组合能够有效提高屏蔽效能。研究了镀银织物以紧密叠放、夹空气层和夹角叠放3种模式构造,采用小窗法屏蔽效能测试系统实测了0～18 GHz宽频段内双层织物的电磁屏蔽效能的增量问题。结果表明：镀银织物双层紧密叠加有利于电磁屏蔽效能提升,其屏蔽效能可达70 dB,明显高于单层织物,紧密叠放更有利于双层织物的屏蔽效能;夹空气层双层织物在0～6.5 GHz频段的屏蔽效能有所提高,而在其他频段其屏蔽效能呈下降趋势,尤其不利于高频电磁波的屏蔽;夹角叠放双层织物屏蔽效能均达到60 dB以上,大夹角叠放(90°)时使双层织物的屏蔽效能降低。建立了双层织物电磁屏蔽效能的增量模型,为电磁屏蔽效能分析提供了一个新的视角,通过结构优化方式探索屏蔽体构造的最佳配置,对电磁屏蔽体的设计、生产及使用具有一定的参考价值。     

多层金属纤维混纺织物的电磁屏蔽效能

金属纤维混纺织物由于具有较好的电磁屏蔽性能得到了广泛应用,但其屏蔽效能受纺织工艺等诸多因素影响,难以建立精确的计算模型。在分析介质平板屏蔽体屏蔽效能的基础上提出等效算法,将金属纤维混纺织物等效为均匀介质平板,以计算多层织物材料的电磁屏蔽效能。通过测试单、双层金属纤维混纺织物的电磁屏蔽效能,验证了等效方法的正确性和可行性,可用于指导复合材料的设计。     

单向取向碳基气凝胶的制备及电磁屏蔽性能研究

碳基气凝胶具有自支撑的三维导电网络,是开发新型高性能电磁屏蔽及吸波材料的研究热点。通过单向冷冻干燥法制备了具有单向取向结构的碳纳米管/壳聚糖(CNT/CS)气凝胶,考察了不同CNT/CS浓度及配比对气凝胶冷冻速率、线性收缩率、微观结构、电导率和电磁屏蔽效能的影响,研究了取向方向对气凝胶导电性能和电磁屏蔽效能的影响。结果表明：CNT/CS气凝胶具有显著的各向异性,取向方向上的电导率最高可达14.34S/m,是垂直于取向方向上的1.5～3.0倍。CNT/CS气凝胶具有优良的电磁屏蔽效能,在12GHz的频率下屏蔽效能最高可达20.3dB。气凝胶在垂直于取向方向上的电磁屏蔽效能高于取向方向。     

电磁屏蔽材料的研究进展

简单介绍了电磁辐射的危害性及发展电磁屏蔽材料的意义,阐述了电磁屏蔽材料的屏蔽原理,较为详细地介绍了表层导电型、填充复合型、导电纤维、导电织物等电磁屏蔽材料及各种材料在工艺上的优缺点;同时阐述了各种电磁屏蔽材料的研究进展和发展前景,预测了电磁屏蔽材料的发展方向.     

电磁屏蔽泡沫混凝土的性能研究

研究了不同密度泡沫混凝土的电磁屏蔽性能,结果表明孔径较大时泡沫混凝土具有电磁屏蔽能。在泡沫混凝土制备过程中加入石墨和碳纤维,改善了泡沫混凝土的电磁屏蔽能。研究了石墨和碳纤维掺量对泡沫混凝土电磁屏蔽能的影响。结果表明,石墨不能增加泡沫混凝土电磁屏蔽能;碳纤维泡沫混凝土在0~100MHz频率范围内,屏蔽效能SE随着频率增加而迅速降低,在100~1500MHz频率范围内,屏蔽效能SE随着频率增加而增加,在100MHz附近,碳纤维电磁屏蔽砂浆的SE最小。     

医用不锈钢的研究与发展

不锈钢由于具有优异的力学性能、耐蚀性能和加工性能而被广泛应用于各种医疗器械及手术工具的制造。概述了医用不锈钢的特点和临床应用,以及存在的主要问题,并以高氮无镍奥氏体不锈钢、不锈钢表面改性、抗菌不锈钢为重点,介绍了医用不锈钢近年来在国内外的主要研究进展。表明医用不锈钢的研究与发展,进一步提高或改善了不锈钢的生物安全性、力学性能、耐蚀性能,甚至带来了一些生物功能化,为医用不锈钢的临床应用带来了新的机遇。     

Unexpected Corrosion Problems by Organic Fat Charged in Loading Tanks of a Cargo Ship

A failure analysis has been conducted on board a cargo ship to assess the extent of corrosion damage. The damage was classified as unusual by the ship owner since the material, an organic fat (namely tallow), was usually loaded into stainless steels on board tanks without any noticeable corrosion problems. The corrosion phenomenon was classified, by the technical crew, as pitting on the bottom of two tanks, particularly the 6p (port tank) and the 6s (starboard tank). The pitting was defined as anomalous since only two tanks were affected and a total of five tanks were made of same stainless steels and loaded with same organic fat mixture. Corrosion pits were found during final inspection by the captain, following load discharge and tanks cleaning operations. The initial inspection was carried out while the cargo ship was harboured at Algeciras (Spain). Because of the observations, the ship remained in harbour for 3 days awaiting inspection by qualified technicians to evaluate the possibility of resuming navigation. The cargo ship was then inspected by one of the authors in collaboration with two metallurgists acting as consultants to the ship owner. The purpose of the inspection was to investigate on damage phenomena, to evaluate the integrity of cargo structures and to decide on two possible options: resuming navigation or immediately ordering a very expensive stop for urgent maintenance. This paper was structured to show documentation (some details have been omitted for propriety reasons) and visual inspection results used to establish failure mechanisms and probable failure-root causes. These results enabled a decision for the cargo ship to resume travel to next dockyard for maintenance operations.

Nickel-free austenitic stainless steels for medical applications

Abstract

The adverse effects of nickel ions being released into the human body have prompted the development of high-nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also much improves steel properties. Here we review the harmful effects associated with nickel in medical stainless steels, the advantages of nitrogen in stainless steels, and emphatically, the development of high-nitrogen nickel-free stainless steels for medical applications. By combining the benefits of stable austenitic structure, high strength and good plasticity, better corrosion and wear resistances, and superior biocompatibility compared to the currently used 316L stainless steel, the newly developed high-nitrogen nickel-free stainless steel is a reliable substitute for the conventional medical stainless steels.     

0Cr13Ni5Mo/Q345C马氏体不锈钢复合板的焊接性

分析了 0Cr13Ni5Mo/Q345C马氏体不锈钢复合板的焊接性。通过抗裂性试验、复合板补焊及复合板对接焊、焊接工艺评定 ,提出了该复合板配套的焊接材料及可行的焊接工艺 ,按此工艺焊接的 0Cr13Ni5Mo/Q345C复合钢板接头的力学性能满足技术指标的要求。     

Factors affecting the oxidation mode of stainless steels

Abstract

Studies have been made to investigate what effect different factors have on oxide formation on stainless steels at 600–1,000°C in air. The factors include the effect of microstructure, airflow rate, surface preparations, residual oxides and variations of the dew point of the air. Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES) and light optical microscope (LOM) were used to characterise the oxides.     

不锈钢中15个元素的ED—XRF分析

不锈钢是应用十分广泛的合金钢,成份的含量对性能有重要影响,湿式化学法材料消耗多,慢,采用ED—XRF同时分析其中15个元素,速度快,效率高,能满足分析要求。     

超低碳含铜铸造不锈钢的组织与腐蚀行为

采用金相显微镜、Ｘ射线衍射、透射电镜、电子探针显微分析手段和多种腐蚀试验方法研究了超低碳含铜铸造不锈钢的析出相种类、成分、结构、形貌、分布及其腐蚀行为。结果表明，含Ｃｕ为２．０％的００Ｃｒ２０Ｎｉ２５Ｍｏ５钢经１１５０℃固溶处理可得到单相奥氏体组织，并具有优良的耐全面腐蚀、晶间腐蚀、点蚀和电化学腐蚀性能。     

不锈钢真空钎焊

简述了不锈钢真空钎焊技术的应用、原理、工艺及设备情况,并概述了不锈钢真空钎焊技术的发展趋势.     

Ferritic stainless steel — A coinage material

General economic and metallurgical requirements, and processing methods for coinage materials are reviewed. The Indian effort at the development of ferritic stainless steels for coinage is discussed. The results of several trials at the Salem Steel Plant towards establishing the appropriate composition and processing route are presented and evaluated.     

Carbon deposition on stainless steel in oxidising environments

Abstract

The formation of low-density carbon deposits onto metallic heat transfer surfaces in industrial environments of high carbon activity can have a deleterious effect on thermal efficiency. Often this deposition occurs under reducing conditions and involves carbide (typically of iron) formation as part of the process. It is possible, however, for filamentous carbon deposits to form at much higher oxygen potentials where carbide formation is not favoured thermodynamically. This study considers one such situation by examining the behaviour of a 20Cr25Ni austenitic steel used as fuel cladding in Advanced Gas-cooled nuclear reactors (AGRs). Carbon deposition has been produced in laboratory by exposure at 550°C to CO₂ containing 1%CO and 1000 vppm C₂H₄; the dissociation of the latter additive generates carbon activities much greater than unity. The oxygen potential of this gas is sufficient to oxidise iron and chromium, of the major alloy constituents, but not nickel. The deposition takes place onto substrates that are prepared as electron microscope samples which are subsequently examined by SEM and HREM (high resolution electron microscopy) techniques. The deposits formed consist of solid carbon filaments, approximately 30 nm in diameter, with turbostratic atomic layering. Each filament contains a 10–20 nm metallic nickel particle near its tip. It is argued, and supported by HREM evidence, that such particles are produced as a direct result of the oxidation of the alloy and that prior oxidation is necessary to produce the observed carbon deposition. It is also shown that inhibition of carbon deposition occurs when the oxygen potential of the depositing gas is increased sufficiently to oxidise nickel.