Ti/(Ti,Cr)N/CrN multilayer coated 316L stainless steel by arc ion plating as bipolar plates for proton exchange membrane fuel cells

Arc ion plating (AIP) is applied to form Ti/(Ti,Cr)N/CrN multilayer coating on the surface of 316L stainless steel (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). The characterizations of the coating are analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Interfacial contact resistance (ICR) between the coated sample and carbon paper is 4.9 m Omega cm(2) under 150 N/cm(2), which is much lower than that of the SS316L substrate. Potentiodynamic and potentiostatic tests are performed in the simulated PEMFC working conditions to investigate the corrosion behaviors of the coated sample. Superior anticorrosion performance is observed for the coated sample, whose corrosion current density is 0.12 mu A/cm(2). Surface morphology results after corrosion tests indicate that the substrate is well protected by the multilayer coating. Performances of the single cell with the multilayer coated SS316L bipolar plate are improved significantly compared with that of the cell with the uncoated SS316L bipolar plate, presenting a great potential for PEMFC application. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Process and challenges of stainless steel based bipolar plates for proton exchange membrane fuel cells

Proton exchange membrane fuel cell(PEMFC)powered automobiles have been recognized to be the ultimate solution to replace traditional fuel automobiles because of their advantages of PEMFCs such as no pollution,low temperature start-up,high energy density,and low noise.As one of the core components,the bipolar plates(BPs)play an important role in the PEMFC stack.Traditional graphite BPs and composite BPs have been criticized for their shortcomings such as low strength,high brittleness,and high processing cost.In contrast,stainless steel BPs(SSBPs)have recently attracted much attention of domestic and foreign researchers because of their excellent comprehensive performance,low cost,and diverse options for automobile applications.However,the SSBPs are prone to corrosion and passivation in the PEMFC working environment,which lead to reduced output power or premature failure.This review is aimed to summarize the corrosion and passivation mechanisms,characterizations and evaluation,and the surface modification technologies in the current SSBPs research.The non-coating and coating technical routes of SSBPs are demonstrated,such as substrate component regulation,thermal nitriding,electroplating,ion plating,chemical vapor deposition,and physical vapor deposition,etc.Alternative coating materials for SSBPs are metal coatings,metal nitride coatings,conductive polymer coatings,and polymer/carbon coatings,etc.Both the surface modification technologies can solve the corrosion resistance problem of stainless steel without affecting the contact resistance,however still facing restraints such as long-time stability,feasibility of low-cost,and mass production process.This paper is believed to enrich the knowledge of high-performance and long-life BPs applied for PEMFC automobiles.

Electrochemical Behavior of Niobium Electrodeposited 316 Stainless Steel Bipolar Plate for PEMFC in Choline Chloride Based Ionic Liquids

Niobium was electrodeposited on 316 stainless steel bipolar plates of a fuel cell in water and air-stable choline chloride based ionic liquids. The electrochemical corruption property of bipolar plates in simulated PEMFC environment was investigated. It was showed that the plating film was distributed on the surface of 316 stainless steel like isolated islands with height less than 50 nm. The XPS, XRD results showed that a smooth and strong chemical inert film of Nb O and Nb2O5 was formed on the surface of 316 stainless steel. In simulated cathodic condition, the corrosion potential of Nb coated stainless steel was improved by 244 m V, whilst in an anodic condition, it was improved by 105 m V. The current densities for the coated 316 stainless steel were decreased to 2.479 4 μA·cm-2 from 14.810 μA·cm-2 at-0.1 V and to 0.576 μA·cm-2 from 13.417 μA/·cm-2 at 0.6 V, respectively. It was implied that the niobium coating effectively decreased the corrosion rate. The results of the electrochemical tests indicated that the corrosion resistance of stainless steel was greatly improved after coated with niobium.

Surface stability and conductivity of a high Cr and Ni austenitic stainless steel plates for PEMFC

In order to use stainless steel as bipolar plate for PEMFC, electrochemical behavior of a high Cr and Ni austenitic stainless steel was studied in the solutions containing different concentration of H2SO4 and 2 mg·L-1 F-, and interfacial contact resistance was measured after corrosion tests. The experimental results show that the passive current density lowers with decreasing the concentration of H2SO4. The interfacial contact resistance between carbon paper and passive film formed in the simulated PEMFC environment is higher than the goal of bipolar plate for PEMFC. Surface conductivity should be further reduced by surface modification.

Conductive and corrosion behaviors of silver-doped carbon-coated stainless steel as PEMFC bipolar plates

Ni–Cr enrichment on stainless steel SS316 L resulting from chemical activation enabled the deposition of carbon by spraying a stable suspension of carbon nanoparticles; trace Ag was deposited in situ to prepare a thin continuous Ag-doped carbon film on a porous carbon-coated SS316 L substrate. The corrosion resistance of this film in 0.5 mol·L^（-1） H_2SO_4 solution containing 5 ppm F- at 80°C was investigated using polarization tests. The results showed that the surface treatment of the SS316 L strongly affected the adhesion of the carbon coating to the stainless steel. Compared to the bare SS316 L, the Ag-doped carbon-coated SS316 L bipolar plate was remarkably more stable in both the anode and cathode environments of proton exchange membrane fuel cell（PEMFC） and the interface contact resistance between the specimen and Toray 060 carbon paper was reduced from 333.0 m？·cm^2 to 21.6 m？·cm^2 at a compaction pressure of 1.2 MPa.

XTEM STUDY ON ION PLATED STAINLESS STEEL MULTI-LAYER FILMS

In this paper, the cross sectional microstructure and crystal structure of ion plated multi layer films of stainless steel (1Cr18Ni9Ti ) were studied by cross sectional transmission electron microscopy (XTEM). The results show that ion plated stainless steel multi layer films are fine grained double phase steel films of austenites and ferrites.Cross section film growing microstructures can be divided into three zones: fine equiaxed crystals, fine columnar crystals and coarse columnar crystals. Interfaces in multi layer films can promote fine grained growing and interrupt columnar grained growing,and improve properties of film materials.

Effect of Annealing on Fly-Line Microstructure and Properties of Explosively Composited Stainless Steel-Stainless Steel Plates

Effect of annealing on "fly-line"(adiabatic sheer line) microstructure and properties of explosively composited stainless steel-stainless steel plates was studied.Results show that the flyline microstructure will diminish through certain annealing process,while the cracks formed from fly-line microstructure will remain.Therefore,fly-line microstructure can be considered as a plastic deformation microstructure and crack source s meanwhile its formation is considered as a special plastic deformation mechanism of metal under explosive load.

Overview of stainless-steel clad-plate welding

Types of bimetal clad plate, manufacturing methods, and their fields of application were summarized. In particular,key aspects of the welding of clad-rolled stainless steel were described, including the weldability of the base and clad metals, design criteria for the transition layer, the selection of the type of welding process and consumables used, types of blanking and welding bevels, preparation and assembly prior to welding, welding procedure requirements, post-weld cleaning and heat treatment, and welding quality inspection. This paper will serve as a reference for the welding technology used in future consumer applications in related fields.

Influence of flash trap profiles on joint properties of friction welded CP-Ti tube to 304L stainless steel tube plate using external tool

Titanium tube and stainless steel tube plate were welded by an innovative friction welding of tube to tube plate using an external tool (FWTPET). Copper was used as an interlayer for joining the dissimilar materials and also to minimize the effect of intermetallics formed at the joint interface. The process parameters that govern FWTPET process are plunge rate, rotational speed, plunge depth, axial load and flash trap profile. Among them, the flash trap profile of the tube has a significant influence on the joint integrity. Various flash trap profiles like vertical slots, holes, zig-zag holes, and petals were made on the titanium tube welded to the stainless steel tube plate. Macroscopic and microscopic studies reveal defect-free joints. The presence of copper interlayer and intermetallics was evident from X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies. The microhardness survey was presented across and along the interface. A novel test procedure called “plunge shear test” was developed to evaluate the joint properties of the welded joints. The highest shear fracture load of 31.58 kN was observed on the sample having petals as flash trap profile. The sheared surfaces were further characterized using SEM for fractography.

Performance analysis of the SAW joint of duplex stainless steel clad plate

Duplex stainless steel clad plate exhibits good performance and is relatively inexpensive,however,some difficulties must be overcome when welding different materials. In this study,submerged arc welding（ SAW） was used to weld Baosteel ship clad plates（ 2205 ＋ DH36）,and the performance of the welded joints was tested. The results indicate that the mechanical properties and the corrosion resistance of the welded joints meet the required specifications. The distribution of the main anti-corrosive elements and the phase ratio of the welded joint are analyzed,thereby indicating excellent uniformity and confirming that the welded joint is corrosion resistant.

Gas metal arc welding of duplex stainless clad steel plates

The 2205 duplex stainless ＋ DH36 clad steel plate was welded by gas metal arc welding（GMAW）, and the welding performance of the clad steel plate was investigated. The results show that the adaptability of the welding procedure for the base metal of carbon steel, the transition layer, and the cladding material is excellent. The test results indicate that the phase proportion and component dilution of the GMAW-welded joints of clad steel plate can be effectively controlled to yield joints with good mechanical properties and corrosion resistance.

Composition and corrosion resistance of palladium film on 316L stainless steel by brush plating

Palladium films with good adhesive strength were deposited on 316L stainless steel by brush plating. Scanning electronic microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy （XPS）, mass loss tests and electrochemical methods were used to study the properties of the films. The brush plated palladium film mainly consisted of palladium. XPS analysis indicated that palladium was present in the films as metal state. The palladium plated stainless steel samples showed excellent corrosion resistance in boiling 20% H2SO4 solution and boiling acetic/formic acids with 0.005 mol/L Br- ions added. The corrosion rates of the palladium plated 316L stainless steel samples were about two orders of magnitude lower than those of the original 316L stainless steel samples. This method provides a possibility to prepare protective palladium films on stainless steel facilities with large areas in industrial sites.

Study on numerical simulation of TA1-304 stainless steel explosive welding

In order to guide the explosive welding experiment of titanium-stainless steel,Three-dimensional numerical simulation of explosive welding,which select TA1 as flyer plate and 304 stainless steel as base plate,is carried out by using the LS-DYNA software and SPH-FEM coupling algorithm in the present study.The explosive welding window is calculated and established.It is found that the numerical simulation results are in good agreement with the experimental results.The displacement,velocity and pressure-time curves of characteristic elements show that the quality of explosive welding composites is superior.It is proved that SPH-FEM coupling algorithm is effective for explosive welding of TA1/304 stainless steel and can effectively guide the selection of explosive welding parameters.

Study on process of roll bonding stainless and carbon steel under non-vacuum condition

The non-vacuum roll bonding method of nickel plating on the base materials is put forward in accordance with the primary problems existed in the roll bonding of stainless/carbon steel. After nickel plating test on the base materials, the microstructure of nickel cladding is observed by scanning electron microscopy （SEM） at high, and room temperature, and the results show that the nickel cladding on base material can be protected from oxidation in the high temperature. Non-vacuum roll bonding tests of nickel plating on base materials are done by the roll bonding equipment, and the roll bonding plates of stainless/carbon steel are obtained. The microstructure and the elements distribution of non-vacuum roll bonding interface are analyzed by optical microscope （OM） and SEM. The results reflect that the nickel plating layer and the base materials bond well.

基于无颗粒银导电墨水在不锈钢表面镀银工艺研究

目的采用无颗粒银导电墨水对不锈钢表面进行镀银研究,以绿色环保工艺替代传统电镀银技术。方法主要研究适用于不锈钢基材的前驱体银源、络合剂种类、不锈钢前处理方法、烧结固化温度对不锈钢表面银层微观结构及性能的影响,获得不锈钢基材上微观结构致密、性能良好的银层。采用X射线衍射仪、扫描电子显微镜、激光共聚焦显微镜、数字兆欧表对在不锈钢表面银膜层进行表征。结果不锈钢通过1,2丙二胺溶液处理后,采用银源草酸银为前驱体,此时银层微观结构最致密,具有最佳的附着力等级(5B)和最低的粗糙度(1.237μm),与1,2-丙二胺络合,乙醇为溶剂时,制备出的银层有机物挥发完全,微观结构致密,并且具有最低的接触电阻0.7Ω和粗糙度0.80μm。烧结固化温度为200℃时银层导电性最好。结论采用无颗粒银导电墨水对不锈钢表面进行镀银的新型工艺银层性能良好,可以简化传统电镀技术复杂的操作流程,减少传统电镀工艺所使用氰化物对人体造成的危害,并弥补应用受限的缺点。

燃料电池电极板材料工艺发展趋势

电极板是燃料电池的关键核心部件,起到分隔气体、提供反应界面、传导电流的作用。根据燃料电池应用工况的不同,电极板的材料选择与制造工艺路线也有所不同。材料工艺是决定燃料电池设计、质量、成本的核心要素。着重论述了金属、石墨、树脂作为电极材料的工艺路线。针对金属电极板材料,论述了车载、航空航天2种工况下不锈钢、钛材的成形设计准则、工艺路线、产品性能,并分析比较了不同成形方法中设备、模具工装和工艺路线的适用性。针对石墨电极材料,对比了硬石墨一次模压成形和柔性板石墨模压成形2种工艺,并根据各自的基材状态选择了合适的工艺路线,同时根据工艺路线的特点分析了产品的优缺点。在复合材料中主要选择了金属、石墨、树脂3种材料,根据制备原理,复合材料双极板有结构复合电极、材料复合电极和工艺复合电极3个研究方向。在结构复合电极方面,主要论述了石墨与金属复合的设计思路和结构特点;在材料复合电极方面,主要论述了热固性树脂和热塑性树脂与石墨复合的工艺路线和产品特点;在工艺复合电极方面,主要论述了微型燃料电池极板的制造理念和方法,并借鉴了微机械加工工艺路线,设计制造了复合工艺极板。最后展望了燃料电池电极板的箔材研发方向、级进模工艺复合生产发展方向和石墨极板设计策略及制备工艺发展方向,以及PPS聚苯硫醚、聚苯胺基PANI的导电阳极材料在微电极板中的应用。

大壁厚不锈钢复合板压力容器建造关键技术及应用

在大壁厚不锈钢复合板压力容器的建造过程中,通过深入研究其技术要点和难点,优化焊接接头结构设计,成功形成了一套完整的新型建造关键技术。这套技术不仅优化了焊接接头结构,还创新了一系列施工方法,包括筒体加热卷制、接头坡口机加工、接管内壁耐蚀层TIG/FCAW自动堆焊、不锈钢衬管液氮冷套、球形封头内壁耐蚀层带极埋弧堆焊、纵环缝窄间隙埋弧自动焊以及管口接头马鞍型埋弧焊等。这些新型建造关键技术的应用,在提高压力容器质量效果的同时,也带来了显著的经济效益,为行业同类型设备的建造提供借鉴。在未来的研究中,可以进一步探索这些技术在其他领域的应用,以实现更广泛的技术交流和合作。同时,对于大壁厚不锈钢复合板压力容器的建造,仍需不断深入研究其材料特性、工艺参数和施工方法,以不断提高设备的性能和安全性。

不锈钢双极板高速冲击成形仿真分析

为探究在不均匀速度下高速冲击的不锈钢双极板变形情况及成形规律,结合箔片气化冲击成形的板料速度场分布,运用LS-DYNA建立不锈钢双极板高速冲击成形有限元仿真模型,分析了该成形工艺下不锈钢双极板的动态变形过程,研究了不均匀冲击速度对双极板流道成形质量的影响。结果表明,不锈钢双极板冲击成形的最小初始冲击速度为350 m·s^(-1),流道脊处的减薄率最大,其余部位减薄率小于30%,随着初始冲击速度的增加,双极板成形深度稳定在0.78 mm以上,填充率稳定在95%。但受限于速度场的不均匀性,单次成形有效区域有限,仿真结果表明多道次成形能够形成一致性较好的多通道不锈钢双极板,最后,通过多道次箔片气化冲击成形实验验证了仿真结果。

脉冲电流对超薄316L板微流道成形精度的影响

目的研究在金属双极板脉冲电流辅助冲压工艺中,将脉冲电流单独作用于保压阶段、冲压阶段以及作用于整个冲压过程(冲压阶段+保压阶段)3种通电方式对极板流道深度及壁厚分布的影响。方法以316L不锈钢薄板作为实验材料,调节流经样品的电流参数,分别为0、10、20、30 A,分析脉冲电流参数和通电方式对极板流道深度及壁厚分布的影响规律。结果在高电参数下,当采用在冲压阶段通电、在保压阶段断电的方式2时,在保压阶段可促进应力松弛,具有最佳的回弹抑制效果,其成形深度回弹可减小73.88%。在不同电参数下,3种成形方式对双极板流道壁厚分布具有相似的影响。槽顶和槽底的壁厚减薄相对较小,减薄量为原板材厚度的2%~6%;流道直壁壁厚减薄为原板厚度的9%~15%;而外圆角和内圆角区域的壁厚减薄较大,达到27%~30%。结论在金属双极板脉冲电流辅助冲压工艺中,以不同方式施加脉冲电流,均可以显著提升流道深度,对壁厚影响并无明显差别。特别地,采用在冲压阶段通电、在保压阶段断电的方式2可以显著提升对流道回弹的抑制效果。

Study on the new materials for fiberboard refiner plate of defibrator

Defibrator is a very important machine in the wood industry for producing fiberboard. The refiner plates are the key parts of defibrator that directly act with the wood, and broken easily. The working life of the refiner plates is of significance to the wood industry. It may affect refining quality, production efficiency, and power consumption. In this paper, the abrasion resistance of the refiner plate made of different materials, the stainless steels and high chromium cast irons, were tested and compared. The results showed that abrasion resistance of refiner plate made of high chromium cast irons was better than that of the stainless steel materials. Although the two kinds of materials have the same compositions, their abrasion resistances have ap-parent difference. The main reason is that the material microstructures have very important effects on their performance. The refiner plates made of developed high chromium cast irons don抰 demand the complex heat treatment. This can simplify the producing process, save the cost of production, decrease labor strength, and increase the production efficiency.