热喷涂用丝材及其喷涂工艺的研究进展

热喷涂技术是通过喷涂粉末或丝材状态的原材料在基体表面得到具有耐高温、耐腐蚀、耐磨损等性能的涂层，从而达到对基体的保护作用。热喷涂粉末材料范围广泛，包括金属、非金属和陶瓷等，但是其生产成本高，利用率低，而且涂层沉积速率慢，喷涂设备复杂。相比之下，丝材展现出了很大的优势，一方面丝材生产成本低，材料利用率高，涂层沉积速率快；另一方面，粉芯丝材的出现解决了陶瓷材料难以制成丝状以及实心丝材成分难以调控的问题，极大地促进了丝材喷涂工艺的发展。目前，丝材喷涂工艺主要有电弧喷涂、丝材火焰喷涂以及等离子转移弧喷涂，其中电弧喷涂和火焰喷涂工艺成熟，在喷涂粉芯丝材和实心丝材方面得到了广泛的应用，但是制备的涂层氧化严重，孔隙率高；等离子转移弧喷涂作为新的丝材喷涂工艺，制备的涂层氧化程度小，孔隙率低，涂层质量好。通过研究喷涂过程中丝材熔融机理和熔滴特性来改进喷涂工艺和设计新型喷涂技术成为提高涂层质量两种主要途径。本文综述了近年来热喷涂所用丝材的研究进展，以及涂层的耐腐蚀、耐高温和耐磨损性能；介绍了丝材火焰喷涂、电弧喷涂和等离子转移弧喷涂的优缺点；对喷涂过程中实心丝材和粉芯丝材的熔化和雾化行为以及粒子的形成进行了...     

双填丝等离子弧增材制造高强高硬高氮钢组织与特性研究

针对等离子单填丝增材制造电弧热量利用率低和熔丝效率低,容易造成增材金属过热的问题,以高氮钢丝材为熔化材料,采用单电弧双填丝共熔池的等离子弧增材制造工艺制备了高氮钢直壁体试样.采用游标卡尺、光学显微镜、扫描电镜和力学性能试验等手段,分别对单填丝和双填丝两种工艺增材直壁体的成型尺寸、熔敷效率、显微组织、力学性能和断裂形式进行了对比检测分析.然后详细考察了丝材熔敷量增加对试样组织和力学性能的影响,并分析双填丝等离子弧增材制造高强高硬高氮钢构件的组织变化规律和性能变化规律.结果表明,相对于单填丝增材工艺,在同样的增材电流下,双填丝增材工艺中总填丝速度可以成倍增加,分层更加清晰,平均有效熔敷效率提高92％.试样的显微组织大部分为平行增材方向奥氏体柱状树枝晶,存在少量的δ铁素体和弥散分布的氮化物,少量奥氏体树枝晶生长的方向出现不一致.在同样的电弧进行速度下,双填丝等离子弧增材制造的试样的抗拉强度均有明显提升,最大提升可达到44 MPa;断后伸长率均有增加,最高提升了9.4％.试样的显微硬度比单填丝增材试样的显微硬度略有提高.     

电弧喷涂粉芯丝材的研究进展与应用

简述了电弧喷涂粉芯丝材的优点及制作工艺,介绍了电弧喷涂粉芯丝材的发展历程,以及耐磨损、耐腐蚀、耐高温电弧喷涂粉芯丝材的最新研究进展,展望了电弧喷涂粉芯丝材的应用前景,指出了金属陶瓷复合粉芯丝材、非晶态粉芯丝材、纳米粉芯丝材是未来电弧喷涂粉芯丝材的发展方向。     

工业用金属丝编织网的快速检测

本文简要介绍用万能工具显微镜检测工业用金属丝织网的方法，并举例说明了其检测及数据处理的过程。     

镍铝复合丝和镍铝合金丝及其涂层

介绍了镍铝复合丝和镍铝合金丝及其涂层的成分、相结构 ,比较分析了涂层的结合强度 ,分析了涂层自结合作用机理 ,估算了喷涂一平方米面积所消耗的丝材及相应用丝材成本 ,介绍了两种材料适用的对象及设备     

钛镍丝材切削性能改进

研究了生产工艺对形状记忆合金TiN i丝材切削性能的影响,结果表明:通过改变丝材的拉拔温度、矫直温度、矫直力等工艺参数,TiN i丝材的硬度及屈服强度、抗拉强度、延伸率等力学性能均发生改变,从而使得丝材的切削性能得到明显改善。     

对电弧喷涂丝材的研究与探讨

在简述电弧喷涂基本原理的基础上,分类介绍了各种电弧喷涂丝材性能特点、发展现状和主要应用,指出了各电弧喷涂丝材的发展方向。     

对电弧喷涂丝材的研究与探讨

在简述电弧喷涂基本原理的基础上,分类介绍了各种电弧喷涂丝材性能特点、发展现状和主要应用,指出了各电弧喷涂丝材的发展方向。     

退火工艺在钨铼热电偶丝材的应用

钨铼丝材在加工过程中易出现断裂、开劈等现象,为了提高材料塑性和热电稳定性,可通过退火处理来改善性能。文章详细阐述了钨铼丝材生产过程中各阶段的退火工艺和作用,通过退火处理,丝材的塑性和热电稳定性得到明显提高。     

Nondestructive Evaluation of a Haulage Rope in a Monocable Continuously Moving Passenger Ropeway

The theoretical basis of detecting wire rope anomalies using permanent magnetic field has been fully established. The local faults (LF) such as broken wires and loss of metal area (LMA) signals are provided by nondestructive evaluation instruments. These signals represent the electronic equivalent of the mechanical anomalies present in the wire rope. The saturating magnetic field of the instrument makes the anomalies visible to the magnetic sensors placed around the rope. The condition of a haulage rope (construction 6X19) in a monocable continuously moving passenger ropeway has been studied using this nondestructive method, and the results are presented in this paper.     

Characterization on strength and toughness of welded joint for Q550 steel

Q550 high strength steel was welded using gas shielded arc welding and three different welding wires without pre- or post-heat treatments. The paper investigates the influence of welding wire on the microstructure, tensile strength and impact toughness of Q550 steel weld joints. Results showed that the microstructure of the weld metal of joints produced using ER50-6 wire was a mixture of acicular ferrite and grain boundary ferrite including pro-eutectoid ferrite and ferrite side plate. Acicular ferrite was mainly obtained in the weld metal of the joints produced using MK·G60-1 wire. Pro-eutectoid ferrite was present along the boundary of prior austenite. Crack initiation occurred easily at pro-eutectoid ferrite when the joint was subjected to tensile. Tensile strength and impact toughness were promoted with increasing acicular ferrite. Tensile strength of the joint fabricated using MK·G60-1 wire was close to that of base metal. And tensile samples fractured at location of the fusion zone, which had lower toughness and thus became the weak region in the joint. Impact absorbing energy was the highest in the heat affected zone. Fibrous region in fracture surfaces of impact specimens was characterized as transgranular fracture with the mechanism of micro-void coalescence. Acicular ferrite microstructure region corresponded to relatively large dimples while boundary ferrite microstructure corresponded to small dimples.     

单根绝缘电线电缆火焰垂直蔓延试验仪校准方法的研究

单根绝缘电线电缆火焰垂直蔓延试验仪是当今检验部门以及化工产品生产企业广泛使用的试验仪器之一。为了确保单根绝缘电线电缆火焰垂直蔓延试验仪的量值准确可靠,为该仪器提供校准的依据,对单根绝缘电线电缆火焰垂直蔓延试验仪的校准方法进行了研究。     

钢丝绳断丝检测仪器评估中标样制作方法研究

标准试样制作是钢丝绳无损检测仪器性能评估中的关键环节,其优劣决定了评估的效率和有效性。通过分析断丝检测流程、揭示影响仪器断丝检测能力的因素后,提出断丝配置的等相对差法和等绝对差法,比较了两者的适用性,等绝对差法对高精度仪器有效,等相对差法对低精度仪器有效。最后提出了评估中优选钢丝绳试样的方法。     

Evaporation of metals by high-density (107 A · cm−2) electrical currents

In the present work, the problem of time evolution of pressure and temperature profiles across a wire through which an electrical current with a density of the order of 10⁷ A · cm^–2 flows is solved. The correct boundary conditions for a metal surface are obtained for the case when this metal is rapidly evaporated as a result of high-power Joule heating. The pressure profile appears under these conditions due to pinch-effect and inertia of thermal expansion of the metal; the temperature profile arises because of intensive evaporation from the surface of the wire. The conditions under which a liquid metal is superheated are formulated. On the basis of the analysis of the experimental results on exploding wires, the conclusion is drawn that decay of the metastable state takes place near the binodal. It is shown that the distribution of fine dispersed vapor bubbles is strongly nonuniform across the wire and the process of expansion of the two-phase mixture is very similar to the motion of a wave.Paper presented at the Fourth International Workshop on Subsecond Thermophysics, June 27–29, 1995, Köln, Germany.     

Effects of Mn and Ti on microstructure and inclusions in weld metal of high strength low alloy steel

Abstract

The influences of alloying elements on chemical composition of non-metallic inclusions, impact toughness and microstructure in weld metals of high strength low alloy steels have been studied. Results indicated that microstructure had changed from a mixture of acicular ferrite, proeutectoid ferrite, ferrite side plates and microphases to a mixture of acicular ferrite, bainite and microphases due to the addition of Mn and Ti. The impact toughness of weld metal was improved correspondingly. The volume fraction and composition of inclusions both influenced the proportion of acicular ferrite. Mn and Si based oxide globular inclusions located at the boundary of acicular ferrite plates in the weld metal produced using C–Mn–Si–Cu wire. When Mn and Ti were added to welding wires, the inclusions within acicular ferrite plates permitted fewer primary acicular ferrite plates to grow into relatively larger dimensions. Secondary acicular ferrites nucleating on pre-existing ferrite plates refined microstructure effectively.     

电镀金刚石线锯的研究现状

电镀金刚石线锯是用电镀的方法在金属丝(线)上沉积一层金属,并在沉积的金属内固结金刚石磨料制成的一种线性超硬材料工具.综述了电镀金刚石线锯的原理、模型和特点,以及制备过程中使用的材料(基体材料、金刚石和电镀液)和工艺及其应用实例,并对电镀金刚石线锯的进一步发展进行了展望.为开展电镀金刚石线锯的研究和生产提供了一定的指导.     

多孔材料抑制瓦斯爆炸传播的实验及机理

利用自行设计加工的断面为30cm×30cm方形爆炸实验管道,对不同参数的金属丝网、泡沫陶瓷材料和多孔泡沫铁镍金属的抑爆效果分别进行了实验研究,结合材料特点,分析了其抑爆机理。实验结果表明,金属丝网、泡沫陶瓷和多孔泡沫铁镍金属对瓦斯爆炸传播均有一定抑制作用,多孔泡沫铁镍金属衰压和阻火效果优于金属丝网和泡沫陶瓷,材料的损坏程度明显降低,对火焰衰减效果增强;测点4,多孔泡沫铁镍金属相比40目40层金属丝网对最大火焰温度的衰减率提高了43.8%,相比Al2O3 7cm大孔泡沫陶瓷提高了34.5%。测点7,多孔泡沫铁镍金属相比40目40层金属丝网体对爆炸超压的衰减率提高了29.9%,相比SiC 5cm大孔泡沫陶瓷提高了22.4%。     

A portable electronic nose based on embedded PC technology and GNU/Linux: hardware, software and applications

This paper describes a portable electronic nose based on embedded PC technology. The instrument combines a small footprint with the versatility offered by embedded technology in terms of software development and digital communications services. A summary of the proposed hardware and software solutions is provided with an emphasis on data processing. Data evaluation procedures available in the instrument include automatic feature selection by means of SFFS, feature extraction with linear discriminant analysis (LDA) and principal component analysis (PCA), multi-component analysis with partial least squares (PLS) and classification through k-NN and Gaussian mixture models. In terms of instrumentation, the instrument makes use of temperature modulation to improve the selectivity of commercial metal oxide gas sensors. Field applications of the instrument, including experimental results, are also presented.     

金属丝强化竖直管蓄冰的实验研究

从冷媒温度、加丝疏密度、丝的材质等方面对加丝盘管蓄冰进行了研究,得到了不同条件下的蓄冰增长情况,并且还分析了加丝蓄冰过程中蓄冰筒体内部的温度变化情况,较完整的了解了加丝强化的效果。