超音速喷涂防磨的应用及质量控制

水冷壁管磨损是循环流化床锅炉受热面磨损删中最突出的问题,采取炉膛内热喷涂或补焊后热喷涂的方法,在水冷壁管磨损区域或部位喷涂金属耐磨层来提高耐磨性。选择喷涂方法与耐磨涂层、喷涂质量检查验收,是炉内热喷涂质量控制的关键。实践表明,在炉膛内进行超音速喷涂金属耐磨层,使水冷壁管因磨损漏泄、爆管得到有效控制。     

耐高温磨蚀涂层在循环流化床锅炉中的应用

循环流化床锅炉是一种节能、环保的新型锅炉 ,但却存在着磨损、腐蚀非常严重的问题。大量研究表明 ,表面涂层技术是解决循环流化床锅炉高温磨蚀问题的一种最经济有效的方法。综述了目前国内外常用的几种循环流化床锅炉耐高温磨蚀涂层 ,对各种涂层的研究应用现状、性能等作了简要分析。结果表明 ,高铬合金涂层和金属 /陶瓷复合涂层以及高速电弧喷涂粉芯丝材工艺具有广阔的应用前景。     

未来高性能发动机活塞环的热喷涂发展

等离子喷涂由于适用材料广泛，能够满足许多摩擦学性能，因而在欧洲得到极大的发展。喷涂参数对于改进涂层结构，从而改进涂层磨损、结合力、内聚力及耐腐蚀性能非常重要。首先研究了喷涂用等离子气体，然后通过试验优选了所有喷涂参数。除喷涂参数外，粉末成份对涂层摩擦学性能也有较大影响。为降低活塞环-缸套摩擦副磨损，对几种粉末进行了对比试验。通过理想化试验与发动机试验相结合，表征了一些钼基涂层的摩擦学行为。     

燃气轮机透平叶轮表面耐磨涂层国产化研制

刷式汽封对燃气轮机透平叶轮体的长期过量磨损,会造成漏气,严重影响燃机发电效率,所以在燃机叶轮与汽封齿摩擦部位喷涂一层NiCr-Cr3C2耐高温磨损涂层,可显著提高其发电效率,延长其使用寿命。东汽表工所利用大气等离子喷涂（APS）技术制备的NiCr—Cr2C3涂层的孔隙率、界面污染率、涂层硬度、涂层结合强度、杯突性能等均满足使用要求该项技术与业内国际知名企业水平相当,并成功应用于F级重型燃机透平叶轮上,从而进一步推进了我国重型燃机国产化进程     

超音速等离子喷涂技术与装备

超音速等离子弧喷涂技术是重要的表面工程技术之一。与其它的喷涂技术相比较,它具有生产效率高、涂层质量好的特点。可以熔化金属、碳化物陶瓷和氧化物陶瓷等材料。乌克兰科学院巴顿电焊研究所研究开发的超音速等离子喷涂技术与装备具有显著的技术优势,其最大工作电流达400A;粉末颗粒飞行速度达到750m／s;各种材料涂层的结合强度大于55MPa;沉积率大于60％;金属粉末的送粉速度高达50kg／h。     

循环流化床锅炉管防磨喷涂

本文对循环流化床锅炉燃烧室卫燃带上部锅炉管采用火焰喷涂防磨层与采用超音速电弧喷涂复合涂层的使用效果进行了对比 ,提出了采用超音速电弧喷涂复合防磨涂层是解决循环流化床锅炉磨损问题的有效途径。     

热喷涂技术及其在锅炉管道防护中的应用

本文介绍了热喷涂过程基本原理,工艺分类和各自特点,锅炉受热面管道的磨损和腐蚀问题,以及热喷涂技术在预防这些问题上的应用。其中对热喷涂工艺,根据锅炉防护的实际需求,着重阐述了高速氧燃料火焰喷涂、等离子体喷涂等两种工艺,简要讨论和比较它们的相对优势。在叙述锅炉管道磨损和腐蚀机理的基础上,强调对于锅炉不同部件由于其工作环境的差异,其主导的磨损腐蚀类型有显著区别,因此需要采用与之相适应的喷涂原材料和喷涂工艺。     

激光处理的等离子喷涂Cr2O3涂层的摩擦学特性

通过对等离子喷涂涂层在Ｎｄ－ＹＡＧ激光处理前和处理后的磨损量对比，研究了激光处理对等离子喷涂Ｃｒ２Ｏ３陶瓷薄涂层的影响，为此，用陶瓷／ＳＡＥ４６２０钢以线接触配对进行了环形试样磨损试验，还讨论了磨损机制和因激光处理引起的涂层中有关孔隙率，显微结构和涂层结合情况的变化。     

高温纳米陶瓷涂层在垃圾焚烧炉上的应用

为解决垃圾焚烧炉受热面发生的高温酸腐蚀、冲蚀磨损与沾污结渣等共性问题,提出采用喷涂高温纳米陶瓷材料进行防腐、防磨、防结渣处理。阐述了高温纳米陶瓷表面材料的性能指标和技术特点,以及喷涂施工工艺。该涂层在某垃圾焚烧炉中,经8 000 h现场服役后,涂层表面完好,检测结果表明该纳米陶瓷涂层对垃圾焚烧炉受热面具有优异的耐腐、抗磨和防结渣的作用。     

水轮机磨蚀防护技术研究进展

磨损、空蚀及其他破坏耦合作用是水轮机常见的破坏形式,在过流部位进行涂层防护是提高抗磨蚀能力的有效方法之一.简述了过流部件磨蚀等破坏的机理及其影响因素,并综述了过流部件耐磨蚀涂层技术的研究进展,评述了不同类型涂层的技术特点,通过金属熔覆技术、抗撕裂聚氨酯材料以及综合防护措施的应用案例阐述了该领域取得的进展,并展望了未来的...     

新型低温辐射金属电热膜的开发和应用

低温辐射电热膜是一种新型的环保采暖材料,针对目前低温辐射金属电热膜产品复合不牢、性能不稳定、安装性差的缺点,对其制造的关键技术进行了研究和试验,提出了各生产工序的技术要点,完善了生产工艺流程.通过对研制的新型低温辐射金属电热膜进行现场测试,各项指标符合技术要求,室内温度达到暖通规范要求.     

Design and fabrication of light weight current collectors for direct methanol fuel cells using the micro-electro mechanical system technique

The direct methanol fuel cell (DMFC) is suitable for portable applications. Therefore, a light weight and small size is desirable. The main objective of this paper is to design and fabricate a light weight current collector for DMFC usage. The light weight current collector mainly consists of a substrate with two thin film metal layers. The substrate of the current collector is an FR4 epoxy plate. The thin film metal layers are accomplished by the thermo coater technique to coat metal powders onto the substrate surfaces. The developed light weight current collectors are further assembled to a single cell DMFC test fixture to measure the cell performance. The results show that the proposed current collectors could even be applied to DMFCs because they are light, thin and low cost and have potential for mass production.     

Numerical simulation to study the effect of repair width on residual stresses of a stainless steel clad plate

Clad plates are widely used in the construction of corrosion resistant equipment. During the repair of clad plates, residual stresses are generated and influence the structure integrity. This paper uses the finite element method (FEM) to predict the residual stresses in a repair weld of a stainless steel clad plate. The effect of repair width on residual stresses has also been investigated by numerical simulation. Due to the material mismatching between clad metal and base metal, a discontinuous stress distribution has been generated across the interface between clad and base metals. The peak residual stress occurs in the heat affected zone (HAZ) of the base metal, because the yield strength of the base metal is larger than that of the clad metal. With an increase in repair width, the residual stresses are decreased. When the repair width is increased to 24 mm, the residual stresses in the weld have been decreased greatly and the peak residual stresses have been reduced to less than the yield strength. Therefore, the recommended repair width should not be less than 24 mm, which provides a reference for optimizing repair welding technology for this stainless steel clad pate.     

固体废弃物循环流化床焚烧惯性分离器涂层材料抗磨损试验研究

采用循环流化床焚烧固体废弃物已成为一种有效的方法.而分离装置是循环流化床燃烧的关键部件之一,在炉膛出口布置惯性分离器可有效分离飞灰,实现物料循环.惯性分离器处于高温、高含尘浓度的工作环境中,因此要求其制备材料具有很强的抗磨损性能.文章选取0Cr13作基材,施加耐磨涂层,通过热态磨损试验研究了两种涂层材料的抗磨损性能.100h试验后结果表明:1号涂层的抗磨损性能要优于2号;高温区所受到的磨损和冲蚀要比低温区严重;涂层施加得愈平整、效果愈好,则其抗磨损性能愈好;涂层中的高铬含量有效增强了涂层抗磨损的能力.     

Efficient hydrogen production from aqueous methanol in a PEM electrolyzer with porous metal flow field: Influence of change in grain diameter and material of porous metal flow field

Previous research has shown that hydrogen production performance of a PEM methanol electrolyzer was largely improved with a porous flow field made of sintered spherical metal powder compared with a conventional groove type flow field. In this study, we experimentally investigated the effect of the change in grain diameter and material of the porous metal flow field on hydrogen production performance in a PEM methanol electrolyzer cell. The experimental results indicated that the hydrogen production performance of the electrolyzer cell was improved by reducing the grain diameter. This could be mainly attributed to the lower interfacial contact resistance by reducing the grain diameter of the porous metal flow field. For investigating the influence of material, cell performances with a stainless steel and a nickel base alloy were compared.     

改性材料电热元件应用于电热锅炉的研究

本文对用一种新型改性材料作为电热锅炉的加热元件进行了研究 ,并对影响该电热元件热力性能的各类因素作了较详尽的分析和探讨 ,提出了优化设计方案 ,旨在为电热锅炉电热元件的研究和设计提供理论依据。     

欧盟钢焊工资质考试标准ISO9606-1与EN287-1对比分析

从2015年10月开始,欧盟钢类别的焊工考试标准EN287-1已经被ISO9606-1替代,两标准在内容上有所不同。本文结合两个标准的内容,从填充材料、熔敷金属厚度及母材厚度的认可范围、试件类型、焊接位置等方面着重分析了两者主要异同点,有利于更深入理解钢类焊工资质考试标准内容。     

Optimisation of metal sputtered and electroplated substrates for solar selective coatings

This study describes the performance of selective coatings to have maximum solar absorptance and minimum thermal emittance, in relation to substrate preparation. Aluminium and copper substrates, covered with sputtered or electroplated metal base layer, have been used to see the influence of different types of substrates for solar selective coatings. The effect of the base layer material, thickness, deposition process and deposition condition, on the optical performance of selective coatings has been analysed. Nickel was electroplated and nickel and vanadium were sputtered as a base layer on the Al and Cu substrates. A comparison of plated and sputtered nickel substrates for Ni:SiO₂ and V:Al₂O₃ composite solar selective coatings is presented. Theoretical results using computer simulation for solar selective composites on various substrates, and the effect of the base layer thickness on these substrates are compared with experimental results. The effects of the base layer thickness for cobalt and tungsten are also included. The sputtered base layers selective coatings produced higher absorptance along with higher emittance and electroplated base layer coatings resulted in comparatively lower absorptance and lower emittance. Hundred nanometre metal sputtered base layer is optimised for solar selective coatings.     

Experimental investigation of fatigue behaviour for welded joint with mechanical heterogeneity

Because of material and mechanical heterogeneity in welded joints, experimental studies of low-cycle fatigue (LCF) life and fatigue crack initiation behaviour were performed on weld metal, heat-affected zone (HAZ) and base metal of 16 MnR pressure vessel steel. A fatigue damage test was carried out by introducing a new damage variable. The fatigue damage evolution laws in each zone of a welded joint were obtained. A circular-notched compact tension specimen was designed and the whole process of fatigue damage, crack initiation and crack growth in each zone was investigated. The effect of mechanical heterogeneity in welded joints on the fatigue damage behaviour and fatigue crack initiation life was also investigated. The experimental and theoretical results indicate that the fatigue behaviour is markedly different in three zones of welded joints; there is a trend toward reduction in the fatigue life of HAZ as compared with the base metal. The weld metal does not have the same fatigue behaviour as confirmed by LCF life and crack growth rate. This study leads to the conclusion that fairly accurate estimates of fatigue life for welded joints should include the whole process of fatigue damage evolution and fatigue crack initiation as well as crack growth. Furthermore, a local experimental method should be carried out for weld metal, HAZ and base metal, respectively. Finally, the local fatigue failure criterion based on the weakest chain model has been presented.     

The effects of vent channels and metal conductive base on thermal characteristics of the active graphite-composite cylindrical heat sink

This study proposed a novel configuration of active LED graphite-composite heat sink and experimentally investigated the effects of vent channels and metal conductive base on the fluid flow and heat transfer characteristics of this active heat sink. The heat sink was made of the graphite powders, aluminum-alloy powders, and adhesive mixed in specific proportion by the vacuum-pressure injection technique. The cost and weight of this graphite-composite material are much lower than those of aluminum alloy. The configuration of heat sink is a hollow circular cylinder with multiple radial fins. Different motor fans can be put in the chamber of heat sink, with various vent-channel positions and orientations (vertical vent channels, horizontal upper-row vent channels, and horizontal bottom-row vent channels) and numbers of channels (24, 36, 48, and 72) in the heat sink to enhance overall cooling performance by driving through airflow. The results indicate that the overall Nusselt number (Nu) of the graphite-composite heat sink with motor fan was 2.23–2.50 times that without motor fan. The numbers of vent channels in heat sink were positively related to the total flow rate of through air. Thus, the heat sink with the most vent channels had the maximum Nu in the motor-fan mode. When an additional annular aluminum-alloy conductive base was mounted in the graphite-composite heat sink with the most vent-channel configuration, the Nu was 35% higher than that without conductive base in motor-fan mode, proving the metal conductive base was effective. The optimal vent-channel configuration in this study was also used for the full aluminum-alloy heat sink, the corresponding Nu of the models without/with motor fan were compared with the full aluminum-alloy heat sink without vent channel, the heat transfer enhancements were about 13% and 127%, respectively.