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我国铸造覆膜砂的生产、应用与展望 总被引:1,自引:0,他引:1
本文论述了我国铸造覆膜砂的生产及应用情况.简要介绍了我国覆膜砂的发展历程,叙述了覆膜砂的特点、原材料的选择、覆膜砂的混制工艺及分类,着重介绍了覆膜砂的制芯(造型)工艺,特别是热芯盒制芯及壳芯制作工艺,对覆膜砂生产铸件常见缺陷及解决措施以及覆膜砂的再生与质量控制作了叙述. 相似文献
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覆膜砂高温膨胀率是覆膜砂最重要的性能,与铸件脉纹、变形缺陷直接相关。介绍了覆膜砂高温膨胀率的检测原理及试验方法,分析了不同覆膜砂的高温膨胀曲线。试验结果表明,低膨胀率覆膜砂有利于减少铸件的脉纹、变形缺陷。 相似文献
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以硅砂和宝珠砂为原砂、酚醛树脂为粘结剂制备覆膜砂,研究了原砂种类、粒度以及树脂加入量对覆膜砂性能的影响.试验结果表明:在原砂粒度为50~200目范围内,制备条件相同条件下,覆膜宝珠砂的强度是相同粒度覆膜硅砂的1.2~1.6倍;原砂太粗或者太细,覆膜砂强度一般,100/50目的覆膜砂强度相对较高;当树脂加入量为0.8%~... 相似文献
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根据壳型生产线十几年运行和各类覆膜砂应用的经验,对壳型铸造用覆膜砂的一些技术问题进行探讨。详细介绍适用于吹砂式多工位壳型机的湿态覆膜砂性能;高强度低树脂量覆膜砂的研制;湿态壳型覆膜砂的成形性指数与调湿工艺;翻斗法制壳时的脱壳问题分析和解决办法;覆膜砂脱壳性检测方法;高镍球铁件壳型铸造表面针孔原因分析与抗针孔覆膜砂的应用。 相似文献
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James Holbery Dan Houston 《JOM Journal of the Minerals, Metals and Materials Society》2006,58(11):80-86
In the past decade, natural-fiber composites with thermoplastic and thermoset matrices have been embraced by European car
manufacturers and suppliers for door panels, seat backs, headliners, package trays, dashboards, and interior parts. Natural
fibers such as kenaf, hemp, flax, jute, and sisal offer such benefits as reductions in weight, cost, and CO2, less reliance on foreign oil sources, and recyclability. However, several major technical considerations must be addressed
before the engineering, scientific, and commercial communities gain the confidence to enable wide-scale acceptance, particularly
in exterior parts where a Class A surface finish is required. Challenges include the homogenization of the fiber's properties
and a full understanding of the degree of polymerization and crystallization, adhesion between the fiber and matrix, moisture
repellence, and flame-retardant properties, to name but a few. 相似文献
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Yuwei Zhai Diana A. Lados Jane L. LaGoy 《JOM Journal of the Minerals, Metals and Materials Society》2014,66(5):808-816
Additive manufacturing (AM) refers to an advanced technology used for the fabrication of three-dimensional near-net-shaped functional components directly from computer models, using unit materials. The fundamentals and working principle of AM offer several advantages, including near-net-shape capabilities, superior design and geometrical flexibility, innovative multi-material fabrication, reduced tooling and fixturing, shorter cycle time for design and manufacturing, instant local production at a global scale, and material, energy, and cost efficiency. Well suiting the requests of modern manufacturing climate, AM is viewed as the new industrial revolution, making its way into a continuously increasing number of industries, such as aerospace, defense, automotive, medical, architecture, art, jewelry, and food. This overview was created to relate the historical evolution of the AM technology to its state-of-the-art developments and emerging applications. Generic thoughts on the microstructural characteristics, properties, and performance of AM-fabricated materials will also be discussed, primarily related to metallic materials. This write-up will introduce the general reader to specifics of the AM field vis-à-vis advantages and common techniques, materials and properties, current applications, and future opportunities. 相似文献
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Y.M.Hao C.X.Cui Y.Gao W.P.Zhao J.S.MengDepartment of Physics Tianjin Normal University Tianjin China School of Materials Science Engineering Hebei University of Technology Tianjin China Manuscript received September in 《金属学报(英文版)》2002,15(4):401-404
An approximate calculation of the exchange interaction constant JRT between the rare-earth sublattice and the transition metal sublattice in R2Fe17-xAlx (R=Tb, Gd, and Dy) compounds is given by the molecular-field model and the results of neutron diffraction. The calculated values, -JR,T/k, for Dy2Fe17-xAlx (x=5, 6, 7 and 8), Tb2Fe10Al7, Gd2Fe17-xAlx (x = 7, 8) compounds are 8.62K, 8.64K, 9.52K, 10.34K and 10.66K, 10.65K, and 9.85K, respectively, they are in agreement with the experimental values, -JR,T/k, of Dy2Fe17-xAlx (x=5, 6, 7 and 8), Tb2Fe10Al7 and Gd2Fe17-xAlx (x=7, 8) compounds, which are 8.77K, 9.25K, 10.1K, 10.9K and 10.35K, 10.1K, and 10.3K, respectively. The origins of the difference between the calculated and the experimental results are discussed. 相似文献
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设计了一种Nb、Ti微合金化低碳复相钢,采用SEM、TEM及力学性能测试等方法研究了退火镀锌过程中热轧复相钢显微组织、析出相和力学性能的演变规律,进行了800 MPa级热基镀锌复相钢工业试制。结果表明,热轧复相钢的显微组织主要由铁素体、马氏体和马/奥岛构成。退火镀锌过程中,马氏体和马/奥岛分解形成高温回火马氏体,铁素体内可动位错密度降低,同时析出纳米级Nb、Ti和Mo的复合碳化物,导致抗拉强度降低、屈服强度和扩孔率显著提高。热基镀锌复相钢的显微组织主要由铁素体和高温回火马氏体构成,屈服强度、抗拉强度、断后伸长率和烘烤硬化值分别为769 MPa、852 MPa、14.5%和43 MPa,扩孔率达到53%,具有良好的力学性能和局部成形性能。 相似文献
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稀土元素在金属材料中的一些物理化学作用 总被引:117,自引:0,他引:117
针对不同金属溶液体系,采用了不同的实验方法,研究得到了铁液中Ce,Y,La,Nd,Sm分别与S,O,S+O,C,N,Sb,Sn Pb,P,Cu,Ti,Nb,V溶质元素,镍液中Ce,Y分别与S,O,S+O溶质元素,铜液中Ce,Y分别与S,O,S+O,Sn,Zn,Pb,Al,Si,Ti,Fe溶质元素,铝液中Ce分别与Mg,Ti,Mn,Zn,Fe,Sn,Pb,Ni,Cu,Si,S溶质元素构成的67个三元 相似文献
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磷酸盐涂料是在磷酸盐粘结剂中添加金属及金属氧化物骨料而形成的一种水性无机涂料。由于磷酸盐涂料固化后所形成的涂层具有机械强度高、防护性能好以及与基体附着力高等优点,已广泛应用于航天、航海以及汽车等工业领域。相比于金属涂层和有机涂层,磷酸盐涂料因其独特的优势而日益受到越来越多的关注。介绍了磷酸盐无机涂料及其组成,并综述了其在腐蚀防护、耐磨减摩、耐高温隔热等领域的应用。首先,详细阐述了粘结剂、固化剂、骨料等组分在涂料中的作用,同时对各组分的研究进展进行了论述。随后,报道了国内外有关的磷酸盐涂料固化成膜理论,分析了磷酸盐在高温和常温条件下的成膜机制。然后,针对磷酸盐涂料所存在的固化温度高、脆性大、韧性差、表面易存在缺陷等不足,总结了有机溶剂、缓凝剂、硅溶胶、石墨烯等对磷酸盐涂料的改性研究。最后,展望了磷酸盐涂料的发展趋势,指出常温易固化涂料配方的开发以及发展有机-无机复合涂层将会是今后研究的重点。 相似文献
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Special features of the structure and properties of cast high-speed steels R6M5K5 and R6M5 modified by REM-based additives, i.e., ferrocerium in a design amount of 0.1, 0.3, 0.6, and 1.2% and silicomishmetal and alumoyttrium in a design amount of 0.1, 0.3, and 0.6% are studied. Results of metallographic, x-ray diffraction, fracture surface, and microscopic x-ray spectral analyses of the steels after casting, annealing, hardening, and tempering are discussed. It is shown that the modifying changes the chemical composition, morphology, and distribution of the carbide component in the steels. Relation between the structural parameters and the characteristics of mechanical properties is determined. 相似文献
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达克罗涂层的无氢脆、耐高温、强耐腐蚀性、附着力良好、高渗透性和强涂覆能力等特点使其近年来广泛用于汽车、家用电器、建筑、石油化工等领域。然而该涂层中的Cr6+由于具有较强的致癌、致畸、致突变作用而受到限制,且其硬度仅有1~2H,抗划伤能力差,耐磨性低,因此使用该图层的工件不适用于硬度和耐磨性要求高的场合。本文先介绍了达克罗涂液的主要组成成分(金属粉末、溶剂、铬酸盐钝化剂和特殊有机物)及铬酸盐在达克罗涂层中的作用(钝化作用、黏结作用和自愈作用);接着从环境友好型达克罗防腐涂层的成膜物质-铬酸盐替代物(无铬钝化剂-含氧酸盐及氧化物、稀土盐和有机黏结剂-硅烷偶联剂、硅烷偶联剂+缓蚀剂、树脂+缓蚀剂)的选取、无铬钝化液的配方优化、纳米微粒增强达克罗涂层三方面分别综述了国内外关于提高环境友好型达克罗涂层的硬度和耐蚀性,指出了各种成膜物质的不足并指出进一步的研究方向;最后简要介绍了稀土改性达克罗处理技术的防腐蚀机理,对环境友好型达克罗涂层研究中存在的问题进行了归纳,并对其发展方向进行了展望。在总结与分析的基础上可知,随着环境保护要求的提高,开发由有机聚合物(硅烷或树脂)和稀土盐... 相似文献
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本文描述了中厚板表面麻坑缺陷宏观形貌、特征,并采用金相显微镜、扫描电镜对中厚板表面麻坑缺陷的形态、组成进行微观分析。结果表明,麻坑缺陷的宏观形貌为连续的片状粗糙面,其下有形状不一、大小不同的凹坑;麻坑缺陷处成分存在Fe、O、Na、Mg、Si、S、K、Ca元素;缺陷处O含量明显增高,证明缺陷处成分主要为铁的氧化物。因此,麻坑缺陷为轧制过程中氧化铁皮、设备锈蚀物等异物掉落到钢板表面并被压入导致。经过优化轧制水冷工艺、除鳞工艺、及时彻底清理设备上堆积的氧化铁皮沉淀物及锈蚀物,可有效控制麻坑缺陷。 相似文献
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近年来,材料表面防护技术已由普通环境下的材料保护技术向苛刻环境下的特种防护技术发展,主要包括高速、高温、高压、重载环境下的长寿命润滑与强化技术,严酷海洋大气、深海环境、辐射环境下的腐蚀与防护技术,以及面向重大装备的维修与再制造技术等。这些技术的发展促进了磁控溅射、多弧离子镀、冷喷涂、热喷涂、智能防腐涂层等多项新技术的发展,并在航空、航天、船舶、兵器、核电等多个重点行业中得到应用。文中对近年来苛刻环境下材料表面防护技术的发展现状和趋势进行了研究,以我国重大工程装备为出发点,重点对材料的腐蚀与防护、减摩与润滑、耐磨与强化以及维修与再制造4个领域技术的新成果、新观点、新方法和新技术进行了综述,为相关的研究工作提供技术参考。 相似文献