Synthesis and magnetorheological characteristics of ribbon‐like,polypyrrole‐coated carbonyl iron suspensions under oscillatory shear

One of the crucial problems of classical magnetorheological (MR) fluids is their high rate of sedimentation. This disadvantage may be substantially eliminated using core‐shell particles. The aim of this study is to prepare spherical carbonyl iron (CI) particles coated with conducing polymer polypyrrole (PPy) with ribbon‐like morphology. Scanning electron microscopy proved the formation of the ribbon‐like layer onto CI particles while Fourier transform infrared spectroscopy confirmed the chemical structure of PPy. The magnetic properties observed via vibrating sample magnetometer showed decreased magnetization saturation of core‐shell‐structured particles due to the existence of non‐magnetic surface layer. MR measurements performed under oscillatory shear flow as a function of the applied magnetic flux density, temperature, and particle concentration showed that core‐shell particle‐based MR suspension exhibits sufficient MR performance for practical applications. Moreover, the suspension stability is promoted significantly when core‐shell particles are used as a dispersed phase. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

添加剂对熔纺氨纶结构与性能的影响

基于添加剂与聚氨酯之间的化学与物理作用,选择了合适的聚合物和无机纳米颗粒等添加剂,研究了这些添加剂对熔纺氨纶制备及其对氨纶丝的微观结构和力学等物理性能的影响。研究结果表明:增塑剂S改善了氨纶的结晶特性,进而改善力学性能与热稳定性;添加剂的并用在一定程度上可改善氨纶丝弹性与耐疲劳性。     

热致性液晶聚芳酯纤维的制备与热处理

热致性液晶聚芳酯(TLCP)纤维是一类具有较高强度与模量的高性能纤维。将由4,4'-二苯醚二甲酸、4-乙酰氧基苯甲酸、1,4-二乙酰氧基苯撑、2,6-萘二甲酸和对苯二甲酸熔融缩聚制得的新型液晶聚芳酯,通过熔融纺丝制得初生纤维,然后经热处理,制备高强、高模TLCP纤维。通过金相显微镜、差示扫描量热仪、热失重仪、纤维强力仪等对该TLCP初生纤维与热处理后的纤维性能进行了研究和表征。     

Preparation and properties of alcohol-resistant thermal transfer printing inks for multifunctional label printing via physical blending of resins

Due to the rise of the logistics industry and the widespread use of ink labels, problems such as the narrow operating temperature range of ink, poor alcohol resistance, and insufficient scratch resistance need to be solved urgently. In this work, creates alcohol-resistant thermal transfer inks by mixing polypropylene chloride (VP-365) and epoxidized hydrogenated bisphenol A (P) resin and incorporating them into the ink formulation. The synthetic ink has a lower glass transition temperature (118.2°C), allowing the ink to print at lower temperatures. It has small wetting angles (68°, 63°, 58°, 46°, and 40°) and a large adhesion force (10.44 – 14.4 N) for different labels. Further, to evaluate the printing performance of the ink, the ink was scratched under 1000 g pressure and in the environment of isopropyl alcohol to evaluate its printing performance. The produced ink has high scratch resistance (300 times) and good alcohol resistance (140 times). Moreover, the developed ink showed good printability, printing media versatility, high adhesion, and excellent alcohol resistance. The synthesis method is facile and cost-effective, which paves a novel way towards high-performance ink printing and thermal transfer technology industries.     

攀长钢万吨钛材生产基地规划

为了研究快速凝固对Al-Ti-B中间合金细化效果的影响,对其进行了熔体快淬处理,在冷却速度为105～106 ℃/s时,得到了薄丝带状细化剂.通过SEM和TEM分析可知,快速凝固后细化剂中的TiAl3由纳米晶和少量非晶态合金组成,尺寸由30～35 μm下降为50～100 nm.分别用薄丝带状和杆状Al-Ti-B中间合金对ZL109进行细化处理时发现:薄丝带状细化剂比杆状细化剂的细化效果好,使ZL109的力学性能有了进一步的提高,抗拉强度提高32.9%,断后伸长率提高15.6%,硬度提高5.69%.因此,快速凝固是提高Al-Ti-B中间合金细化效果的有效途径.     

非晶带材生产线用磁性卷取辊吸附特性分析

根据对起卷吸附过程的力学分析建立完成起卷所需满足的力学条件。基于麦克斯韦电磁方程组,采用数值模拟方法对磁性卷取辊起卷吸附过程进行二维瞬态分析,探讨了永磁铁布局对磁吸附力的影响规律。对卷取辊外侧永磁铁布局结构进行优化,并通过模拟计算得到起卷吸附过程中磁吸附力随气隙的变化规律。模拟结果表明:在给定的气隙及空间范围内,磁性卷取辊能够克服各个阻力并完成起卷过程。     

TiNiCu形状记忆合金薄带研究进展

TiNiCu形状记忆合金薄带凭借其窄相变滞后、优异的形状记忆效应与超弹性、良好的热循环稳定性成为一种很有前途的微驱动器材料。本文全面阐述了国内外在TiNiCu薄带研究方面的最新进展,主要包括晶化行为、显微组织、马氏体相变行为、形状记忆效应与超弹性,重点介绍了热处理工艺-显微组织-性能之间的内在联系,探讨了TiNiCu薄带今后的研究重点     

D-KH法制备AgCuSn合金钎料的性能研究

分别采用熔铸法和D-KH法(叠轧复合-扩散合金化工艺)制备了Ag-22.4Cu-20Sn钎料合金,采用XRD、SEM、DSC及万能力学试验机等测试技术,对合金相组成、显微组织、熔化特性、钎焊接头的剪切强度和钎焊界面形貌等进行了对比研究。结果表明,D-KH法制备的钎料相组成为(Ag)、Cu3Sn、Ag5Sn相,而熔铸法制备的钎料相组成为(Ag)、Cu3Sn、Ag5Sn以及Cu41Sn11相;D-KH法制备的钎料合金液固相线均降低,熔程减小。与熔铸法相比,用D-KH法制备得到的厚度0.1 mm的钎料薄带,润湿铺展性更优、接头剪切强度更高、接头强度稳定性更好。     

叠片式非晶磁环性能的研究叠片式非晶磁环性能的研究

用非晶材料Fe91.7Si5.3B3.0制备两个尺寸完全相同的叠片式和盘绕式磁环,然后对这两个磁环的磁性能进行比较。发现频率较低时,叠片式的饱和磁感应强度比盘绕式磁环的低,当频率逐渐升高时,叠片式磁环的饱和磁感应强度高于盘绕式磁环。对于矫顽力和磁导率,叠片式始终占据优势。实验中,盘绕式磁环在盘绕和胶的固化过程中引入了径向应力,因此导致其磁性能与叠片式磁环的差距。所以径向应力对磁环的性能有一定的影响。     

非晶带材成形用冷却铜辊内流道传热数值模拟

非晶带材成形采用急速冷却方法,其中冷却铜辊内流道设计是非晶带材成形装备研究中的关键问题。根据带材成形的冷却工艺要求,提出了冷却铜辊内流道设计准则。在此基础上,设计出4种典型的冷却铜辊内流道结构。采用流-固耦合传热方法对所设计的4种不同的冷却铜辊内流道流场进行数值模拟分析,得到了不同流道结构所对应的压力场、温度场随进水流量的变化规律。为了评价内流道的换热能力,提出了内流道综合换热系数作为量化换热能力的指标。分析表明:散射肋形流道进出口压降较小,且其换热能力优于其他3种结构,适用于冷却铜辊内流道结构。