NiTi-W原位复合材料的马氏体相变与性能

为获得高性能NiTi基记忆合金复合材料,通过熔炼、锻造、拔丝等手段获得一种NiTi-W原位复合材料。利用SEM扫描电镜观察材料显微组织;DSC测试材料的马氏体相变行为;利用WDT II-20万能拉伸试验机测试材料的力学性能。SEM分析结果显示,拔丝加工使W纤维直径细化至几微米,甚至亚微米级别,在NiTi基体中沿拔丝方向一致排布。DSC测试结果显示,材料经不同温度退火后展现出复杂的可逆马氏体相变行为,在某些升、降温曲线上出现多个吸放热峰现象。拉伸测试结果显示,600 ℃退火样品经适当的预拉伸变形后,屈服强度会大大增加,由~200 MPa提升到~800 MPa,断裂应力超过1 GPa,断裂应变高达40%,材料展现出优秀的线性超弹性,是一种集高强度、高塑性、高线性超弹性于一身的高性能材料。     

“Lattice Strain Matching”-Enabled Nanocomposite Design to Harness the Exceptional Mechanical Properties of Nanomaterials in Bulk Forms

Nanosized materials are known to have the ability to withstand ultralarge elastic strains (4–10%) and to have ultrahigh strengths approaching their theoretical limits. However, it is a long-standing challenge to harnessing their exceptional intrinsic mechanical properties in bulk forms. This is commonly known as “the valley of death” in nanocomposite design. In 2013, a breakthrough was made to overcome this challenge by using a martensitic phase transforming matrix to create a composite in which ultralarge elastic lattice strains up to 6.7% are achieved in Nb nanoribbons embedded in it. This breakthrough was enabled by a novel concept of phase transformation assisted lattice strain matching between the uniform ultralarge elastic strains (4–10%) of nanomaterials and the uniform crystallographic lattice distortion strains (4–10%) of the martensitic phase transformation of the matrix. This novel concept has opened new opportunities for developing materials of exceptional mechanical properties or enhanced functional properties that are not possible before. The work in progress in this research over the past six years is reported.     

沥青拌和站燃油系统的改造

近年来随着国际市场原油价格的不断攀升,筑路工程的最主要的原料沥青和燃油也在随之急剧升高,节约能源已成为我们现在的主要目标.     

国内外钢铁工业固相二次资源利用现状、存在问题与对策

为了剖析当今钢铁工业固相二次资源的利用水平、存在问题,提出解决途径,进一步提高工业绿色和低碳水平,本工作介绍了钢铁工业的气相、固相和液相二次资源内容,概述了国内外钢铁工业固相二次资源(以下称：固废)的研究和利用现状。由于钢铁工业固废利用的难点和堵点是钢渣的利用,本工作重点以钢铁工业钢渣为例,介绍了其在国内外的利用概况、存在的共性问题,并提出了解决的途径。由于钢渣是在现有炼钢的特有高温物化环境中产生的,导致钢渣成为一种过烧的硅酸盐产物,其活性差、易磨性差、含铁量高,还含有一定量的游离氧化钙(f-CaO),给钢渣资源和热量的回收及利用都带来了非常大的难度,以至于全世界对钢渣资源和余热的利用还没有找到理想的方法。因此,钢渣成为世界钢铁工业固相二次资源绿色处理和低碳利用的难点和堵点。本工作在剖析了钢铁工业固废利用技术目前存在的各类问题基础上,根据当前国家政策法规的要求,针对上述存在问题提出了应对的对策途径,为钢铁工业固废下一步高效、绿色和高值利用,提供了建议和研究方向。     

Hydrothermal epitaxy and resultant properties of EuTiO3 films on SrTiO3(001) substrate

We report a novel epitaxial growth of EuTiO₃ films on SrTiO₃(001) substrate by hydrothermal method. The morphological, structural, chemical, and magnetic properties of these epitaxial EuTiO₃ films were examined by scanning electron microscopy, transmission electron microscopy, high-resolution X-ray diffractometry, X-ray photoelectron spectroscopy, and superconducting quantum interference device magnetometry, respectively. As-grown EuTiO₃ films with a perovskite structure were found to show an out-of-plane lattice shrinkage and room-temperature ferromagnetism, possibly resulting from an existence of Eu³⁺. Postannealing at 1,000°C could reduce the amount of Eu³⁺, relax the out-of-plane lattice shrinkage, and impact the magnetic properties of the films.

PACS

81.10.Aj; 81.15.-z; 61.05.-a     

Transition-metal-doped NiSe2 nanosheets towards efficient hydrogen evolution reactions

Nano Research - Transition metal diselenides are promising electrocatalysts for hydrogen evolution and therefore different approaches have been proposed to enhance their catalytic activity. Herein,...     

基于数值评价的隧道衬砌裂缝成因分析与维修设计

地下工程衬砌裂缝是隧道工程常见病害之一。由于衬砌裂缝对隧道结构体受力、防排水等安全方面产生不良影响,有必要对裂缝成因加以分析并采取有效措施来降低裂缝对隧道的影响。以四川省某铁路隧道为研究对象,现场调查衬砌裂缝情况,分析隧道边墙纵向开裂原因。采用应力解除法对该隧道进行地应力测试,测点处围岩初始应力处于极高应力状态,分析得出高地应力作用是导致衬砌开裂主要原因。为检验这一推断,采用扩展有限元(XFEM)对该段衬砌结构性能进行数值模拟,根据XFEM得到破坏区域衬砌结构破坏演化、二衬安全系数,模拟结果与实际衬砌损伤形式一致。最后,针对隧道衬砌结构开裂提出一种具体的维修方案,根据数值计算结果及现场施作情况,验证所提维修方法的有效性及安全性。     

电脉冲对取向硅钢凝固组织的影响

对熔融态钢液进行处理,研究了电脉冲对于取向硅钢凝固组织的影响作用,利用正交试验法研究了脉冲电容、频率、处理时间和电压等脉冲参数的作用效果.结果表明:电脉冲对钢锭晶粒组织具有明显的细化作用,凝固组织的等轴晶比例大幅上升,影响等轴晶比例的最显著性因素为脉冲频率,最优正交试验参数为电容1 200μF,脉冲频率1 Hz,处理时...     

基于多相整流的船舶电力推进系统谐波抑制

变频器等电力电子设备在船舶电网中的使用,将使变频器输入回路产生大量谐波.为减小谐波对电网的污染,对6脉波、12脉波、24脉波整流器的输入侧电流谐波进行了分析,对船舶电力推进系统不同工况下的网侧电流谐波进行了仿真研究.仿真结果表明,多相整流技术是抑制谐波的有效方法,整流相数越多,变频器注入电网的谐波含量越小;24脉波整流应用在船舶推进系统上可大大减小船舶电网的谐波含量,有效地提高电网品质.     

基于能耗指标分解模型的某厂节能瓶颈分析

将能耗指标分解模型应用在某厂的主要生产流程中,通过对吨钢综合能耗的分解计算,从物质流和能量流的角度来评价分析该厂的能耗现状,挖掘节能潜力.分析发现该厂高炉和烧结工序的产品结构因素是限制吨钢综合能耗进一步下降的瓶颈环节.结合生产实际,提出了提高转炉废钢比、改善高炉燃料结构、降低烧结机漏风率等较有针对性的措施,并量化了转炉废钢比及烧结机漏风率与能耗之间的关系,以期为该厂未来的节能工作提供可行的思路和方向.