Automotive carbon fiber: Opportunities and challenges

The carbon fiber industry is growing, with steadily increasing demand from the aerospace and defense markets as well as smaller markets such as sporting goods and construction materials. Infiltration of the automotive market remains a challenge, however, and so the U.S. Department of Energy's (DOE) FreedomCAR program has made the development of low-cost automotivegrade carbon fiber its highest priority for materials research. The DOE effort is currently focused on three objectives: developing low-cost carbon fiber precursors, low-cost conversion methods, and high-throughput fabrication processes.     

The formation of protective nitride surfaces for PEM fuel cell metallic bipolar plates

The selective gas nitridation of model nickel-based alloys was used to form dense, electrically conductive and corrosion-resistant nitride surface layers, including TiN, VN, CrN, Cr₂N, as wellas a complex NiNbVN phase. Evaluation for use as a protective surface for metallic bipolar plates in proton exchange membrane fuel cells (PEMFC) indicated that CrN/Cr₂N based surfaces holdpromise to meet U.S. Department of Energy (DOE) performance goals for automative applications. The thermally grown CrN/Cr₂N surface formed on model Ni−Cr based alloys exhibited good stability and low electrical resistance in single-cell fuel cell testing under simulated drive-cycle conditions. Recent results indicate that similar protective chromium nitride surfaces can be formed on less expensive Fe−Cr based alloys potentially capable of meeting DOE cost goals.     

The DOE advanced gas reactor fuel development and qualification program

The high outlet temperatures and high thermal-energy conversion efficiency of modular high-temperature gas-cooled reactors (HTGRs) enable an efficient and cost-effective integration of the reactor system with non-electricity-generation applications, such as process heat and/or hydrogen production, for the many petrochemical and other industrial processes that require temperatures between 300°C and 900°C. The U.S. Department of Energy (DOE) has selected the HTGR concept for the Next Generation Nuclear Plant (NGNP) Project as a transformative application of nuclear energy that will demonstrate emissions-free nuclear-assisted electricity, process heat, and hydrogen production, thereby reducing greenhouse-gas emissions and enhancing energy security. The objective of the DOE Advanced Gas Reactor (AGR) Fuel Development and Qualification program is to qualify tristructural isotropic (TRISO)-coated particle fuel for use in HTGRs. An overview of the program and recent progress is presented.     

柴油机油压与转速的无损检测

柴油机油压波形中包含了大量可作为供油系统故障诊断的特征参数和转速变化的信息。介绍了基于PC/104处理器用油压外卡传感器实现柴油机油压与转速无损检测的技术和方法,对供油系统发生故障时的油压波形特征进行了分析,并介绍了基于油压波形测试柴油机转速和加速度动力性能的方法。试验表明,该检测方法方便可行。     

A multiprocess machine tool for compound micromachining

Compound micromachining is the most promising technology for the production of miniaturized parts and this technology is becoming increasingly more important and popular because of a growing demand for industrial products, with an increased number not only of functions but also of reduced dimensions, higher dimensional accuracy and better surface finish. Compound micromachining processes that combine multiple conventional and non-conventional micromachining processes have the capability to fabricate high aspect ratio microstructures with paramount dimensional accuracy. Such machining should be carried out on the same machine with minimum change of setups. At the same time, on-machine tool fabrication along with on-machine tool and workpiece measurement facilities should also be available for further enhancement of the functionality of the machine and higher productivity. In order to achieve effective implementation of compound micromachining techniques, this research seeks to address four important areas, namely (a) development of a machine tool capable of both conventional micromachining including microturning, micromilling, etc., and non-conventional micromachining including microelectrical discharge machining (micro-EDM), wire-cut electrical discharge machining (WEDM), etc.; (b) process control; (c) process development to achieve the necessary accuracy and quality and (d) on-machine measurement and inspection. An integrated effort into these areas has resulted in successful fabrication of microstructures that are able to meet the miniaturization demands of the industry. This paper presents a few tool-based approaches that integrate micro-EDM, micro-EDG, microturning and microgrinding to produce miniature components on the same machine tool platform in order to demonstrate the capabilities of compound micromachining.     

Development of spot weld failure parameters for full vehicle crash modelling

Abstract

A cost and time effective process was developed to create spot weld failure parameters for crash models implemented in LS-DYNA. The process includes a design of experiment (DOE) approach for coordinating data collection, welding and testing, finite element modelling, statistical analysis, validation, and implementation. The DOE approach was used to coordinate testing of a reduced set of samples over a large range of material strengths and gauges. This testing included cross-tension, lap shea, and coach peel type evaluations. Computer models for each metal combination and sample geometry were developed to obtain normalised tensile, shear and bending stress at the incidence of weld failure. These normalised loads were then regressed to extend these results to all possible material combinations within the DOE space. These results were then used to estimate the spot weld failure parameters for all the stack-ups of interest. A set of multiweld T-section samples were then welded, physically tested and computer modelled to validate the failure parameters developed from the small single weld tests.     

水性无机富锌涂料的防腐性能研究

无机富锌涂料具有杰出的耐侵蚀性能、耐溶剂性、耐辐射性、耐热性,在恶劣腐蚀环境下是用于钢结构件的最佳涂料之一。选取了几种具有代表性的水性无机富锌涂料进行研究,通过测试涂层的渗水性、抗盐雾性能、电化学保护性能,深入分析并比较了这几种水性无机富锌涂料防腐性能的优劣性。实验结果表明：GZH202型与FZ-1型无机富锌涂料具有较好的防腐性能,而LW-1型和IC531型水性无机富锌涂料的防腐性能相对较差。实验结果为进一步研究水性无机富锌涂料的使用提供了很好的参考价值。     

用不同方法测定的淬火油冷却性能的数字化

建立了淬火油冷却性能的数字化模型.通过试验确定,符合国际标准ISO 9950:1995的国标GB/T 30823-2014/ISO 9950:1995《测定工业淬火油冷却性能的镍合金探头试验方法》(热电偶在探头心部)可以被采用.按中国石化行业标准SH/T 0220-92(热电偶在银探头心部)和日本标准JIS K2242...     

Heißkorrosion durch Verbrennungsrodukte von Heizölen hoher und mittlere Dichte

High-temperature corrosion by products of combustion of fuel oils of high and medium density The author describes a pilot plant for the investigation of the corrosive attack by products of combustion of heavy and light fuel oils on 18 different materials at 650, 700 and 750° C; test conditions are maintained widely comparable. The materials were selected in view of the technical suitability for the construction of turbine blades. The following fuel oils were used: (a) heavy fuel oils having a high ash content; (b) oils having a low ash content; (c) a light fuel oil to which the author added, gradually and in the form of oil-soluble compounds, the elements S, Na and V which are considered as mainly responsible for the corrosion. The oils mentioned under (c) permitted to show that

• 1 The three elements mentioned, in the form of their compounds formed during combustion, are mainly responsible for the corrosion;
• 2 It is not an individual element or its compounds but the combination of the three aggressive ash species which produces the damages found in the tests.

Thanks to this investigation the solution of the problem of corrosion by fuel oils has brought a little closer to its final solution although another considerable research effort will have to be made in order to establish such measures as might be able to prevent such corrosion.     

直接甲醇燃料电池阳极催化剂载体的研究进展

阳极催化反应的反应动力学缓慢是限制直接甲醇燃料电池(DMFC)技术发展的主要原因之一,其中催化剂载体对阳极催化反应有重大影响,载体材料的选择对于决定催化剂乃至燃料电池的性能、效率、稳定性和成本都至关重要。基于对30多篇文献的分析,本文分类综述了用于DMFC碳基催化剂载体包括炭黑、介孔碳、碳纳米管(CNTs)、石墨烯和碳纤维纸,非碳基催化剂载体包括金属有机框架(MOF)、新型二维材料MXenes、钛基材料等材料的研究进展。     

Optimization of corrosion process of stainless steel coating during cleaning in steel brewery tanks

The aim of this research was to optimize and investigate effects of corrosion process during cleaning of stainless‐steel coatings in microbrewery tanks and to predict their resistance to nitric acid in washing solution. Experimental conditions were limited with minimal concentration of acid that satisfied requirements of sanitation protocol, and maximal concentration of acid that did not cause corrosion and release of metals higher then prescribed law limits. Process was monitored by release of metal ions and optimized by design of experiment (DOE) using software Design‐Expert. This approach proved to be very beneficial, cost reductive, and effective for optimization of complex systems. The results of experiments prediction were compared to additional testing, and their matching proved the effectiveness of modeling. Therefore DOE is an effective tool for estimation of steel coating corrosion processes. In addition, optimized values satisfied required criteria, so the proposed protocol can be used in the effective sanitation of industrial tanks and pipelines in brewing industry.     

Influence of Processing Parameters on Residual Stress of High Velocity Oxy-Fuel Thermally Sprayed WC-Co-Cr Coating

Residual stress in high velocity oxy-fuel (HVOF) thermally sprayed WC-10Co-4Cr coating was studied based on design of experiment (DOE) with five factors of oxygen flow, fuel gas hydrogen flow, powder feed rate, stand-off distance, and surface speed of substrate. In each DOE run, the velocity and temperature of in-flight particle in flame, and substrate temperature were measured. Almen-type N strips were coated, and their deflections after coating were used for evaluation of residual stress level in the coating. The residual stress in the coating obtained in all DOE runs is compressive. In the present case of HVOF thermally sprayed coating, the residual stress is determined by three types of stress: peening, quenching, and cooling stress generated during spraying or post spraying. The contribution of each type stress to the final compressive residual stress in the coating depends on material properties of coating and substrate, velocity and temperature of in-flight particle, and substrate temperature. It is found that stand-off distance is the most important factor to affect the final residual stress in the coating, following by two-factor interaction of oxygen flow and hydrogen flow. At low level of stand-off distance, higher velocity of in-flight particle in flame and higher substrate temperature post spraying generate more peening stress and cooling stress, resulting in higher compressive residual stress in the coating.     

Rupture testing as a tool for developing planar solid oxide fuel cell seals

One of the critical issues in designing and fabricating high-performance planar solid oxide fuel cell (pSOFC) stacks is the ability to hermetically seal adjacent metal and ceramic components. In our pSOFC development program, we have designed a testing technique that allows us to screen through the numerous variables involved in developing glass seals. Using this test for example, we have found that the composition of the metal component plays an important role in the strength of the seal. Microstructural analysis of as-sealed specimens revealed that an interfacial reaction zone forms during joining, and it appears that the thickness and composition of this layer are the dominant parameters that control joint strength. In this paper the details of the seal test are reported. The results have proven particularly significant in the development of the next-generation stack design. Supporting microstructural and chemical analyses collected on the test specimens are also presented and used to interpret the seal test results in an effort to identify the necessary steps toward improving glass pSOFC seals. This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National Laboratory, and T. Dubois, U.S. Army CECOM.     

Physico-chemical properties of carbon nanotubes as supports for cathode catalysts of fuel cells. Surface structure and corrosion resistance

Multiwalled carbon nanotubes (CNTs) were synthesized by catalytic pyrolysis of methane on iron-cobalt or cobalt-molybdenum catalyst and investigated by electrochemical and physico-chemical methods before and after chemical or electrochemical corrosion treatment. It is shown that CNTs have a higher corrosion resistance than does turbostratic carbon (carbon black) in corrosion testing under the same conditions. This is expressed in a smaller change in the amount of oxygen on the surface of the carbon material, the values of the electrochemically active surface area (EAS), and in significant differences of these quantities for the CNTs compared to carbon black. Quantitative comparison of the results of chemical and electrochemical treatment of CNT and carbon black, which was performed in this paper for the first time, leads to the conclusion regarding the advantages of corrosion testing by chemical method. Chemical testing simulates to a greater extent the long-term testing conditions of the supported catalysts composed of membrane-electrode assemblies of fuel cells in terms of evaluating the stability of the carbon material as a support of the catalytically active centers.     

基于B/S模式的液压系统远程维修保障系统

提出了将虚拟仪器技术和网络技术应用于工程装备液压系统的远程故障检测、诊断与维修系统中，介绍了该系统的功能结构和软、硬件组成。讨论了远程维修保障系统实现的关键技术问题，分析了其在工程装备液压系统维修中的应用实例。实际应用表明，该系统可大大提高液压系统的故障检测、诊断与维修保障能力。     

Overview of thermal barrier coatings in diesel engines

An understanding of delamination mechanisms in thermal barrier coatings (TBCs) has been developed for diesel engine applications through rig tests, structural analysis modeling, nondestructive evaluation, and engine evaluation of various TBCs. This knowledge has resulted in improved TBCs that survive se-vere cyclic fatigue tests in high-output diesel engines. Although much conflicting literature now exists regarding the impact of TBCs on engine performance and fuel consumption, changes in fuel consumption appear to be less than a few percent and can be nega-tive for state-of-the-art diesel engines. The ability of the TBC to improve fuel economy depends on a num-ber of factors, including the fuel injection system, combustion chamber design, and initial engine fuel economy. Limited investigations on state-of-the-art diesel engines have indicated that surface- connected porosity and coating surface roughness may influence engine fuel economy. Current research efforts on TBCs are primarily directed at reduction of in-cylinder heat rejection, ther-mal fatigue protection of underlying metal surfaces, and possible reduction of diesel engine emissions. Significant efforts are still required to improve the plasma spray processing capability and the economics for complex-geometry diesel engine components.     

玻璃钢试件红外热波检测能力研究

红外热波无损检测的检测能力是一个受到普遍关注的问题，所谓检测能力一般是指对某种特定材料所能检测到缺陷的最小尺寸和最大深度。笔者采用航空航天常用玻璃钢材料，设计出六个形状相同、深度不同的斜槽型空气缺陷的试件，这样的设计能够体现缺陷尺寸和深度的线性变化。试验通过调整加热能量和热像仪采样频率探索该试件检测能力的最佳试验条件，分析在不同深度下所能检测到的最小缺陷的尺寸。     

NEW DEVELOPMENTS IN WROUGHT 718-TYPE SUPERALLOYS

Research and development efforts are still very active on 718-type alloys although two major members of this widely used family, 718 and 625, were invented almost a half-century ago. Emphasis in this type of work at ATI Allvac is directed at improving existing alloys and developing new alloys to meet ever-increasing industrial demands. The improvement of existing alloys is exemplified by addition of minor elements P and B in alloy 718. The discovery of the beneficial effect of P and B in wrought alloy 718 led to development of a new, modified alloy, Allvaca 718 ERa. A large effort has also been directed at studying the effects of major element modifications in 718-type alloys, and a new alloy, Allvaca 718PlusTM, has been developed. The new alloy has much better high temperature capability‘, especially thermal stability‘, approaching the level of Waspaloy but retains excellent processing characteristics, similar to alloy 718. Alloy 718Plus^TM should be useful in any 718-type application requiring a higher working temperature. The properties and processing of this alloy are introduced in this paper.     

Influence of t-ZrO2 addition on mechanical property and electrical conductivity of YSZ electrolyte

8YSZ material that has high electrical conductivity is widely used as electrolytes for solid oxide fuel cells (SOFCs). But its low strength and low fracture toughness hampered the development of SOFCs. In order to find a best method to improve the capability of YSZ electrolyte, the effects of 3Y-TZP additive on the density, strength, conductivity and microstructure were studied by means of X-ray diffraction and Vicker's hardness apparatus. The strength and conductivity of YSZ electrolyte doped with different amounts of 3Y-TZP were determined. It is shown that the samples sintered at 1450 ℃ for 2 h are the best in properties. When 3Y-TZP powders are added to the YSZ system, the results demonstrate that strength of the electrolyte increases remarkably, and the fracture toughness is improved. The electrical conductivity is lowered only slightly. The results display that the flexural strength and the fracture toughness of ceramics with 30wt.% TZP reach 300 MPa and 3.7 MPa·m1/2 , respectively, and the conductivity at 1000 ℃ reaches 0.11 S·cm-1 .