铁镀层在集束拉拔法生产金属纤维中的应用

为了减少酸洗过程对环境的污染,并很好地解决铁铬铝及镍基合金纤维制备过程中基体与隔离层高温下相互扩散的问题,采用电镀法在316L不锈钢丝表面沉积镀铁层,经过穿管、拉拔、退火、电解等工序,制备出12μm不锈钢纤维,并与铜镀层制备的同规格纤维进行了对比。结果表明:该纤维化学成分符合GB/T 20878-2007规定,未引入杂质元素;纤维表面质量较差,存在明显的析出物及沟槽;纤维断裂强力与延伸率较小,需要通过对电镀丝进行退火处理及改用带水冷装置的线材连续退火炉进行退火等措施加以改进。     

机械合金化制备纳米级超细晶不锈钢的研究

用机械合金化的方法制备了纳米级超细晶不锈钢粉末,用X射线衍射仪及扫描电镜技术研究了机械合金化过程中粉末颗粒尺寸及晶粒度的变化.结果表明,随着球磨时间的延长,粉末颗粒的尺寸先略微增大,而后一直减小到约几个微米后保持不变;而粉末的晶粒一直减小,球磨时间达到1 844min左右就达到纳米级.     

复合纳米纤维静电纺丝法的制备及其磁性

以聚乙烯吡咯烷酮（PVP）和金属盐为原料,利用静电纺丝法成功制备出了摩尔比为1：1的SrTiO3-SrFe12O19磁电复合纳米纤维。并通过FT-IR,XRD,SEM和VSM等技术对纤维前驱体及其产物的结构、热处理产物的物相、形貌及磁性能进行了表征。结果表明,样品经900℃焙烧2h后,即可得到纯的SrTiO3和SrFe...     

静电纺丝法制备磁性纳米纤维材料的研究进展

磁性纳米纤维材料不但具有普通纳米粒子的特殊效应,而且具有独特的形状各向异性和磁晶各向异性效应,在高密度磁记录、电磁波吸收、催化剂、医学和生物功能材料等领域具有重要应用。静电纺丝技术已被证明是一种制备纳米纤维最简单有效的方法。结合最新文献,重点阐述了以静电纺丝技术为主的磁性纳米纤维制备工艺以及不同工艺对磁性纳米纤维的形貌和性能的影响。简要介绍了磁性纳米纤维的应用,指出了发展新型结构可控磁性纳米纤维材料、研究其定向排布及组装技术、开发其在各领域的实际应用是未来主要的研究方向。     

晶化法制备的纳米晶材料的研究现状

介绍了非晶合金晶化法制备纳米晶材料的各种工艺过程和特点，综述了该法的影响因素、机理等方面的现今研究成果，对该法的发展及应用前景作了展望。     

奥氏体不锈钢纤维/铜复合体磁学性能研究

在304奥氏体不锈钢纤维物理性能研究中,发现奥氏体不锈钢在纤维化过程中出现磁性,并且纤维/铜复合体的饱和磁化强度δs大于对应去除铜层的纤维束,而矫顽力呈现相反的规律,该实验结果在反复测试中具有很好的重现性.XRD、SEM和VSM等测试表明铜在界面处向纤维扩散,不锈钢纤维/铜复合体去除铜界面后,部分亚稳相奥氏体恢复到平衡态;是引起不锈钢纤维/铜复合体磁性异常变化的原因.     

静电纺丝法制备LaMnO3微／纳米纤维

以聚乙烯吡咯烷酮（PVP）为络合剂与Mn（CH3COO）2和La（NO3）3·6H2O反应制得前驱体，用静电纺丝法制备了PVP／Mn（CH3COO）2·La（N03）3纤维，经煅烧得到具有高比表面积的LaMnO3微／纳米纤维。并采用红外光谱（IR）、X射线衍射（XRD）、扫描电镜（SEM）等现代分析手段对所制备的纤维进行了表征。结果表明：焙烧后纤维的直径明显减小，在150-300nm之间：PVP特征吸收峰消失，新生成的M-O吸收峰随着焙烧温度的升高变强；XRD分析出现相应氧化物的特征峰，说明有LaMnO3的生成。     

纳米纤维制备及其应用研究

纳米纤维,在狭义上是指直径为纳米量级的超细纤维,在广义上讲包括纳米尺度而长度较大的线状材料,还包括将纳米颗粒填充到普通纤维中对其进行改性的纤维。本文介绍了狭义范围上纳米纤维的制备方法及其应用,并对纳米纤维应用发展方向进行了展望。一、纳米纤维的制备方法目前,纳米纤维的制备方法有很多,包括拉伸法[1]、模板合成法[2-3]、相分离法[4]、自组装法[5]、分子喷丝板纺丝法[6]、限域合成法[7]、海岛型双组分复     

催化剂对乙醇催化燃烧法制备碳纳米纤维的影响

分别以硝酸铁、硝酸钴、硝酸镍以及氯化铁、氯化钴、氯化镍作为催化剂先体，利用乙醇催化燃烧法制备了碳纳米纤维。利用扫描电子显微术、透射电子显微术和X射线能量分散谱术对样品进行了表征。讨论了不同种类的催化剂先体对产物形貌和生长机制的影响。     

乳液共混法制备PANI/PAN复合纳米纤维

采用乳液共混法,在N,N二甲基甲酰胺( DMF)中进行聚苯胺(PANI)的乳液聚合,并将该乳液与聚丙烯腈(PAN)的DMF溶液共混形成PANI/PAN复合分散体系;通过静电纺丝技术制备PANI/PAN复合纳米纤维.利用傅里叶红外测试仪(FT-IR)、紫外可见分光光度计(UV-vis)对乳液聚合产物进行了鉴定;利用数显电...     

碳纤维复合材料空间反射镜制造技术研究进展

碳纤维复合材料(CFRP)具有比刚度高、热稳定性好,可设计性强等特点,成为轻量化反射镜制造的新型理想材料,特别适合大口径、高分辨率空间反射镜的制造。简单介绍空间光学反射镜的国内外研究应用的现状。根据反射镜的特点介绍了碳纤维复合材料的材料选择要求,以及国外常用碳纤维复合材料预浸料体系。碳纤维复合材料反射镜制造方法与传统光学材料反射镜的制造不同,一般采用高效、快速、制造成本低的复制工艺来实现。总结了碳纤维复合材料反射镜的复制工艺和反射镜复制精度的影响因素,影响因素包括复制模具、预浸料铺层、反射镜变形、纤维印痕现象、尺寸稳定性以及反射镜尺寸等,并对前五项影响因素提出相应的控制措施来减小影响程度。重点阐述了反射镜纤维印痕现象的成因和解决方法,以及控制尺寸稳定性的关键。     

Direct laser fabrication of three dimensional components using SC420 stainless steel

Direct Laser Fabrication (DLF) has been used in the fabrication of three-dimensional (3D) near net-shape metallic parts using stainless steel SC420 powder. The mechanical properties and microstructure of the as-deposited SC420 and of hot isostatically pressed DLF builds were investigated as a function of deposition direction and sample size using tensile testing, scanning electron microscopy and X-ray diffraction. The influence of the build geometry and orientation on the microstructure and the mechanical properties was also assessed. From this work, it was evident that the DLF process can produce three dimensional parts with good mechanical properties (yield strength > 1000 MPa, tensile strength > 1400 MPa, elongation > 5%), which approach the properties of wrought products.     

316L不锈钢表面沉积Pd／Fe磁性薄膜的研究

采用真空电弧离子镀技术在316L不锈钢表面沉积Pd／Fe薄膜，通过XRD衍射、SEM电镜及EDS分析了薄膜的组织结构、磁性能及电化学行为。结果显示：沉积态Pd／Fe薄膜经过500℃×15min真空扩散热处理后，薄膜由无序的fcc结构相转变成具有铁磁性的L10型fct结构的有序Pd／Fe舍金相，表面光滑均匀且致密，结合强度高，充磁后表面剩磁值达到12Gs，并且提高了材料的耐腐蚀性能。     

Employment of fiber laser technology to weld austenitic stainless steel 304 l with aluminum alloy 5083 using pre-placed activating flux

The overlapping welding was carried out in keyhole mode between austenitic stainless steel 304 l and aluminum alloy 5083 using a low power fiber laser in continuous irradiation. The significant content of magnesium as the alloying element with low boiling point and high vapor pressure inside the AA 5083 matrix can induce the spatter formation and depression on surface of the weld beads upon laser beam absorption and temperature growth which can deteriorate the mechanical properties and appearance of the joints. To reduce these defects, a variety of single and multi-components activating fluxes including oxide-based TiO₂ and halide-based CaF₂ flux powders were pre-placed on the surface of welding material prior to laser welding. The EDX and XRD analyses in addition to microhardness and shear tests were carried out to characterize the joints. The obtained results showed that, the oxide and halide activating fluxes can significantly improve the joints' strength up to 1.48 and 1.85 times in average respectively compared with autogenous joint. It was deduced that the simultaneous effect of significant decrease in joints' surface depression leading to welds' geometry improvement in addition to less formation of interfacial Fe–Al intermetallics, were the major causes for considerable strength improvements.     

Efficient fabrication of ultrafine-grained 316L stainless steel surfaces for orthopaedic applications

Commonly used severe plastic deformation (SPD) methods are suitable for fabrication of bulk nano and ultrafine-grained metals. Drawbacks of these methods include durability of dies, geometrical restrictions and reduced ductility of the products. In this study, two common machining techniques used in manufacturing of orthopaedic components, turning and milling, were applied on 316L stainless steel as surface SPD to refine the surface microstructures of the workpiece. Machining with optimised parameters resulted in substantial grain refinement down to 98?nm on the surfaces. Biological experiments showed up to ～70% and ～280% increased bone cell density on milled and turned samples compared to conventionally machined 316L stainless steel at 5 days, which was correlated with nanocrystallisation and nanoroughness of the samples.     

不锈钢纤维混纺织物微波反射性能研究

对不同掺量比例的不锈钢纤维/涤棉、不同入射角度和厚度的织物进行了微波反射性能测试研究,结果表明,在5%～30%(质量分数)不锈钢纤维掺量中,随着不锈钢纤维含量增加,织物的微波反射率呈现先增大后减小的趋势,当不锈钢纤维含量为20%(质量分数)时反射率达到最大。并对影响微波反射特性相关因素进行了分析探讨。     

磁导率检测技术对430不锈钢构件检测的最优激励频率设计研究

磁导率检测技术是一种可高精度评价铁磁构件整体或部分区域应力集中、疲劳损伤状况的无损检测方法。依据磁导率检测原理,以430铁素体不锈钢试件为研究对象,研究激励电压幅值、激励线圈匝数、检测线圈匝数及外加拉应力对检测传感器最优激励频率的影响。研究发现,最优检测频率随激励线圈匝数的增加而减小;最优检测频率与外加拉应力有关,当外加拉应力超出试件的弹性变形阶段时,最优频率随拉应力的增大而增大;最优检测频率不随激励电压幅值、检测线圈匝数的变化而变化,但随着激励电压幅值、检测线圈匝数的增加,检测灵敏度升高。该研究结论可为灵敏传感器的设计提供参考。     

Effect of fabrication method on the structure and properties of a nanostructured nickel-free stainless steel

An ASTM F2581 nanostructured stainless steel was fabricated by two different powder metallurgy routes; Hot Powder Forging (HPF) and Binder Assisted Extrusion (BAE) methods. Their structure and mechanical properties were investigated and compared. In both fabrication methods, the alloy powder was made by using main alloying elements through mechanical alloying, along with the addition of a sintering aid. In the BAE method, a paste was prepared by mixing alloy powders with polymer followed by cold extrusion, polymer removal, and sintering. In the HPF method, the alloy powders were hot forged under high pressure. The structure and the size of the austenite crystallite of the samples were investigated by scanning electron microscopy (SEM), FE-SEM, x-ray diffraction (XRD) and transmission electron microscopy (TEM). It was determined that the samples prepared by the HPF method are generally denser than those made via BAE. The porosities are smaller and almost uniform in size and morphology in the HPF method. Furthermore, microhardness and tensile tests were performed on the samples. The results show that the ductility of BAE samples is higher than the HPF samples. The fracture surface of the BAE sample has deeper dimples, indicating higher ductility for BAE samples. On the other hand, both the hardness and strength of HPF samples are higher than those of the BAE samples. The results show that both methods produced specimens with considerably higher strength and hardness than conventional 316L stainless steel.     

马氏体时效不锈钢热处理工艺优化

利用热力学计算软件Thermo-Calc,研究了马氏体时效不锈钢Fe-13Cr-7Ni-4Mo-4Co-2W在不同温度下的基体组织和析出相的变化.通过TEM、SADP法分析研究了马氏体时效不锈钢在固溶处理与时效处理过程中显微组织与析出行为.热力学计算与实验研究结果一致表明,马氏体时效不锈钢高温析出Laves-Fe2Mo相,固溶温度超过1050℃,Laves-Fe2Mo相全部溶解;时效析出R相,其含量在8%左右.根据计算结果优化了相应的热处理工艺,力学性能研究结果表明,用所确定的时效工艺进行热处理后,马氏体时效不锈钢的强韧性最好.     

基于MEMS技术的微型模具制作工艺研究

针对微型模具的结构和精度要求,在研究硅模具和背板生长两种工艺路线的基础上,提出了无背板生长工艺路线,并介绍了工艺路线中所涉及的三种MEMS加工方法,即UV-LIGA技术中的光刻、微电铸以及硅MEMS加工技术中的湿法刻蚀.实验结果表明,硅模具和背板生长模具呈54.74°的斜面,且硅模具容易损坏,背板生长模具受应力影响易产生变形;而无背板生长工艺能够获得侧壁垂直、表面细致、使用寿命长的模具,满足结构和精度要求.