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为了探究高温乏油环境下氟橡胶(FKM)摩擦性能的变化规律并改善其摩擦性能,在FKM中加入氧化铝(Al2O3),通过机械共混法制备得到FKM/Al2O3复合材料,在常温和200℃高温乏油环境下对比分析FKM/Al2O3复合材料与FKM材料在不同载荷下的摩擦学性能。结果表明:高载荷和高温使得FKM的摩擦因数、粗糙度和磨痕深度增大,因而乏油环境下FKM的摩擦性能大幅下降;Al2O3粒子的加入提高了FKM在常温和高温下的基体硬度,使得FKM/Al2O3复合材料在相同条件下相比FKM的摩擦因数、粗糙度和磨痕深度均有减小;Al2O3作为补强材料提高了FKM基体在高温乏油环境下的摩擦性能,复合材料表面分层剥离现象明显减少。复合材料表面元素分析结果表明,Al2O3粒子在FKM表面形成了固体润滑膜,改... 相似文献
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非金属夹杂物容易引起钢轨疲劳损伤,为了探究非金属夹杂物特征参数对重载钢轨疲劳性能的影响规律,文中采用ABAQUS有限元软件建立重载钢轨分析模型,对外载荷作用下含夹杂物钢轨的应力状态进行仿真计算,通过FE-SAFE疲劳仿真软件对含多夹杂物钢轨进行疲劳寿命预测。结果表明:相比于软质塑性MnS夹杂物,硬质脆性Al2O3夹杂物对钢轨最大应力的影响更大;夹杂物位于钢轨的高应力区时,在外部载荷作用下,曲线段钢轨的最大应力大于直线段钢轨的最大应力;相邻夹杂物相距临界距离时,多夹杂物水平分布时比其垂向分布时对钢轨应力的影响更大,且随着相邻夹杂物距离变小,钢轨基体的最大应力变小;相邻多夹杂物会使钢轨疲劳寿命骤减,含4个相邻夹杂物的钢轨比含2个夹杂物钢轨的疲劳寿命短。 相似文献
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以Al2O3、TiC粉体为原料,采用无压烧结技术制备了TiC-Al2O3导电陶瓷复合材料,研究了TiC体积分数(30%~45%)对陶瓷复合材料微观结构和性能的影响。结果表明:TiC-Al2O3导电陶瓷复合材料主要由Al2O3和TiC两相组成;随着TiC含量的增加,陶瓷复合材料的相对密度降低,开口气孔率增大,当TiC体积分数为30%时,相对密度最大,开口气孔率最低,分别为95.5%和3.0%;陶瓷复合材料中导电相TiC均连接为网状结构,随着TiC含量的增加,TiC所形成的网状结构越发完整,陶瓷复合材料的硬度先升高后降低,电阻率和断裂韧度均呈降低趋势,抗弯强度增大;当TiC体积分数为45%时,陶瓷复合材料的抗弯强度最高,电阻率最低,分别为361 MPa和6.95×10-6Ω·m。 相似文献
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萧柯则 《机械工人(热加工)》1998,(9):26-27
夹杂类缺陷是铸件含有各种金属和非金属夹杂物的总称。非金属夹杂物是存在于铸件中的非金属相,金属夹杂物则是与基体金属颜色显然不同的异型金属块。夹杂物的存在,破坏了合金基体的连续性,造成合金组织不均匀、影响了合金的力学性能和铸造性能等,为提高铸件质量,近年来对减少夹杂物数量的各种途径进行了研究并取得了显著进展。 相似文献
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以SnO2粉、CuO粉、Nb2O5粉、Cr2O3粉为原料,采用粉末冶金技术烧结制备(98.95-x)SnO2-1CuO-0.05Nb2O5-xCr2O3(x=0,0.01,0.02,0.03,0.05,物质的量分数/%)压敏电阻,研究了Cr2O3掺杂量对该压敏电阻微观结构和电气性能的影响。结果表明:随着Cr2O3掺杂量的增加,烧结试样的相对密度、收缩率、平均晶粒尺寸均先增大后减小,当Cr2O3物质的量分数为0.02%时相对密度和收缩率最高,Cr2O3物质的量分数为0.01%时晶粒尺寸最大,粒径分布最均匀;随着Cr2O3掺杂量增加,SnO2 相似文献
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以Al2O3-(W,Ti)C为基体层,Al2O3-TiC为夹层,采用热压烧结工艺制备了力学性能较好的贝壳仿生陶瓷刀具材料,对材料的层数、层厚比和界面形状等叠层结构参数进行优化,测试材料的力学性能,并对其微观组织进行分析。分析结果表明,当层数为3、层厚比为3时,材料有较好的综合力学性能。在层间引入不同的界面形状,刀具材料的力学性能相较于无界面形状的刀具材料得到了提高,在所制备的试样中,最佳的断裂韧性、维氏硬度和抗弯强度分别为7.16MPa·m1/2±0.04MPa·m1/2,20.40GPa±0.07GPa和981.72MPa±10.86MPa。 相似文献
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采用Bridgman炉结合BaZrO3/Al2O3复合模壳对Ti-46Al-8Nb(原子分数/%)合金进行定向凝固,研究了合金的界面侵蚀层形貌、显微组织和物相组成,以及选晶器角度对选晶效果及合金片层取向的影响。结果表明:定向凝固合金底部存在厚10μm左右的侵蚀层,且随着高度增大,合金的氧含量和侵蚀层厚度增加;合金的凝固组织为由γ(TiAl)和α2(Ti3Al)相组成的全片层结构且无夹杂物存在;在30°~60°区间内,选晶器角度越小,选晶效率越高,但选晶器角度对合金片层取向与生长方向的夹角没有影响。 相似文献
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Xiaodong NIU Surinder SINGH Akhil GARG Harpreet SINGH Biranchi PANDA Xiongbin PENG Qiujuan ZHANG 《Frontiers of Mechanical Engineering》2019,14(3):282
Rapid prototyping (RP) or layered manufacturing (LM) technologies have been extensively used to manufacture prototypes composed mainly of plastics, polymers, paper, and wax due to the short product development time and low costs of these technologies. However, such technologies, with the exception of selective laser melting and sintering, are not used to fabricate metallic products because of the resulting poor life, short cycle, poor surface finish, and low structural integrity of the fabricated parts. The properties endowed by these parts do not match those of functional parts. Therefore, extensive research has been conducted to develop new additive manufacturing (AM) technologies by extending existing RP technologies. Several AM technologies have been developed for the fabrication of metallic objects. These technologies utilize materials, such as Ni-, Al-, and Ti-based alloys and stainless steel powders, to fabricate high-quality functional components. The present work reviews the type of materials used in laser-based AM processes for the manufacture of metallic products. The advantages and disadvantages of processes and different materials are summarized, and future research directions are discussed in the final section. This review can help experts select the ideal type of process or technology for the manufacturing of elements composed of a given alloy or material (Ni, Ti, Al, Pb, and stainless steel). 相似文献
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针对在轨制造功率约束与金属增材成形高能量输入的矛盾问题,提出一种激光焦耳复合热源金属细丝增材制造工艺,激光功率仅约50 W,成功制造了宽高比高达40的薄壁结构,使用焦耳热加热丝材可以大大减少激光的功率,从而控制总的热输入,并对成形过程进行有效的热量管理,引入热阻概念进行递变参数优化的方法,有效减小了增材制造特有的台阶效应,成形件表面质量好,表面粗糙度Ra小于5 μm,优于激光选区熔融(Selective laser melting,SLM)工艺,同时,成形件无气孔和裂纹等缺陷,成形件的抗拉强度、致密度以及硬度分布等性能指标,也很接近制造原材料。结果表明,该激光焦耳细丝沉积(Laser Joule fine wire deposition,LJ-FWD)工艺,可以成为高表面质量零件增材制造的一个有吸引力方案,特别适合应用于太空在轨增材制造的快速成形。 相似文献
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Neng Li Wei Liu Yan Wang Zijun Zhao Taiqi Yan Guohui Zhang Huaping Xiong 《机械工程学报(英文版)》2021,34(3):195-210
Important progresses in the study of laser additive manufacturing on metal matrix composites(MMCs)have been made.Recent efforts and advances in additive manufacturing on 5 types of MMCs are presented and reviewed.The main focus is on the material design,the combination of reinforcement and the metal matrix,the synthesis principle during the manufacturing process,and the resulted microstructures as well as properties.Thereafter,the trend of development in future is forecasted,including:Formation mechanism and reinforcement principle of strengthening phase;Material and process design to actively achieve expected performance;Innovative structure design based on the special properties of laser AM MMCs;Simulation,monitoring and optimization in the process of laser AM MMCs. 相似文献
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Study of mechanical properties of AISI 316 stainless steel processed by “selective laser melting”, following different manufacturing strategies 总被引:1,自引:1,他引:0
Itziar Tolosa Fermín Garciandía Fidel Zubiri Fidel Zapirain Aritz Esnaola 《The International Journal of Advanced Manufacturing Technology》2010,51(5-8):639-647
Considering additive manufacturing (AM) as a field of major interest, this paper is focused on the study of the mechanical properties and their variability with manufacturing orientation (anisotropy) for a metallic alloy manufactured by AM, using the technology of selective laser melting (SLM). This study has been performed on an austenitic stainless steel—AISI 316 L—used for many industrial fields as chemical, cellulose, and medical, among them. Finally, the obtained properties have been analyzed and compared, for this steel, to those properties standardized and tested for “wrought” products. In this paper, previously published results are complemented, as the mechanical tests have been performed in all the possible directions of manufacturing by SLM and not only in two main directions. High mechanical values have been obtained, especially yield strength (significantly improved, compared with wrought or cast products) while keeping high values of ductility and notch impact resistance. For widespread industrial acceptance, AM parts need to be produced to high tolerances and with well-understood mechanical properties, and the aim of this paper is to contribute to this objective. 相似文献
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激光选区熔化技术及其在个性化医学中的应用 总被引:3,自引:1,他引:2
激光选区熔化是一种精密金属增材制造技术,可以成形任意复杂的功能零件。个性化医学用品需要具有个性化的几何外形和良好的生物性能,为了探究激光选区熔化在个性化医学用品中的应用,采用DiMetal系列激光选区熔化设备成形医用金属材料如316L不锈钢、CoCrMo合金、Ti6Al4V,并对医用金属材料成形致密度、成形力学性能和几何结构成形性进行了研究。通过个性化设计和DiMetal系列激光选区熔化设备,设计与制造了个性化牙冠、舌侧正畸托槽、手术模板、全膝置换股骨远端假体、股骨近端假体、颅骨修复体等医学用品。研究证明DiMetal系列激光选区熔化装备、工艺可用于个性化医学用品的快速制造,这为个性化医学用品的快速响应设计与制造提供了一种新的手段。 相似文献
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《Measurement》2016
The significant amount of research has been done in improving the mechanical properties (compressive strength), dimensional accuracy (length, height and width), and build time of the components manufactured from the additive manufacturing process. In contrast to this, the research in the optimization of environmental characteristic i.e. energy consumption for the additive manufacturing processes such as selective laser sintering (SLS), and selective laser melting (SLM) needs significant attention. These processes intakes the significant portion of input laser energy for driving the laser system, heating system and other machine components. With world moving towards globalization of additive manufacturing processes, the optimization of laser energy consumption thus become a necessity from productivity and as well as an environmental perspective. Therefore, the present work performs the empirical investigation by proposing the optimization framework in modelling of laser energy consumption of the SLS process. The experimental procedure involves the computation of energy consumption by measuring the total area of sintering. The optimization framework when applied on the experimental data generates the functional expression for laser energy consumption which suggests that the slice thickness is a vital parameter in optimizing it. The implications arising from the study is discussed. 相似文献
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Sharma Faladrum Dixit Uday Shanker 《Journal of Mechanical Science and Technology》2019,33(9):4439-4449
A fuzzy set based cost model for additive manufacturing is proposed. The model is illustrated through an example of selective laser sintering (SLS), a commonly used additive manufacturing (AM) process. Initially, a deterministic cost model is developed. It is then converted to a fuzzy set based model by considering uncertainty in build time estimation and cost components. For the specific case of SLS, a build time estimation procedure is developed as a part of the cost model. A method to evaluate the reliability of the cost estimate in AM and its significance is also introduced. The cost model is illustrated through two examples of products manufactured by SLS.
相似文献18.
Ruth Jill Urbanic Robert W. Hedrick Syed Saquib Navid Nazemi 《The International Journal of Advanced Manufacturing Technology》2018,95(9-12):3167-3184
Process planning for hybrid manufacturing, where additive operations can be interlaced with machining operations, is in its infancy. New plastic- and metal-based hybrid manufacturing systems are being developed that integrate both additive manufacturing (AM) and subtractive (machining) operations. This introduces new process planning challenges. The focus of this research is to explore process planning solution approaches when using a hybrid manufacturing approach. Concepts such as localized AM build ups, adding stock to a CAD model or section for subsequent removal, and machining an AM stock model are investigated and illustrated using virtual simulations. A case study using a hybrid laser cladding process is used to demonstrate the opportunities associated with a hybrid solution. However, unlike machining, the process characteristics from system to system vary greatly. These are portrayed via a high power, high material deposition feed rate laser cladding system. There are unique challenges associated with AM processes and hybrid manufacturing. New tools and design rules need to be developed for this manufacturing solution to reach its potential. 相似文献
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R. I. Nigmetzyanov S. K. Sundukov D. S. Fatyukhin V. V. Grib S. K. Kartsov 《Russian Engineering Research》2017,37(12):1070-1073
Additive manufacturing methods are briefly reviewed. Proposals are outlined for the use of ultrasound in fused deposition modeling (FDM) and selective laser melting (SLM). Approaches to ultrasonic additive manufacturing (UAM) are discussed. 相似文献
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增材制造液压元件的设计自由度高,目前主要依赖于人工经验,尚缺乏科学的设计准则和方法来指导增材设计,从而科学有效地设计出轻量化、集成化、节能化程度更高的液压元件。总结了一套传统液压阀块的轻量节能设计方法,提出了降低流道局部压力损失的3种设计准则:圆弧过渡准则;最大转角半径准则;转弯数最小准则。在此基础上,对液压阀块进行了重新优化设计并采用选区激光熔化技术(Selective laser melting,SLM)制造。与传统原型液压阀块相比,增材制造成形液压阀块的质量减轻了81%,空间体积减小了46%,同时主油路压损降低了20%以上,表明新型液压阀块的设计同时实现了轻量化和液压能传输效率的提高。最后,还提出了一套液压阀块的增材设计流程,可为轻量节能型液压元件的增材设计提供理论指导。 相似文献