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采用微分扫描式量热法(DSC)、拉伸试验和弯曲试验研究了形变对Ti36Ni49Hf15高温形状记忆合金相变及双程形状记忆效应的影响.结果表明,形变不影响合金的相变顺序.在马氏体状态下变形时,随形变量的增加,Ti36Ni49Hf15合金的马氏体相变温度略有下降,逆马氏体相变温度上升.当形变量一定时,合金在马氏体状态下不同温度变形,对合金的相变温度没有显著影响.Ti36Ni49Hf15高温记忆合金在马氏体状态下直接变形可以产生双程形状记忆效应,其双程可逆应变量随形变量的增加而增加.在随后的热循环过程中,合金的双程形状记忆效应在最初的几次循环过程中迅速下降,而后随循环次数的增加趋于稳定. 相似文献
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用差示扫描量热仪(DSC)和透射电子显微镜(TEM)研究了具有单程和双程形状记忆效应的近等原子比 TiNi 合金的相变行为。结果表明,在降温过程中,单程和双程记忆合金的相变行为分别为B_2→M 和B_2→R→R+M。R 相变属于一级相变,它不是予马氏体,而是和双程记忆效应相关的。 相似文献
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很久以来,人们一直认为钛是生产发动机阀门的优异材料,但钛的高成本是汽车用钛的一大障碍.丰田汽车公司采用Ti-6Al-4V合金生产了汽车发动机的过气阀门,而排气阀门用含Zr、Mo、Ni的高温合金制造,TiB2作为稳定剂,以粉末冶金方法生产.至今,钦在汽车上的用量极为有限.尽管本田公司已采用了粉末冶金汽车连杆,于!991年在其Acllra型Sedan六缸发动机汽车上使用;宝马和欧洲的一些汽车公司对钛铝或金属门化合物发动机阀门进行了试验;美国通用汽车公司也对相似的合金进行了测试,但对汽车来说,钛合金价格相对还是太高了.另外,汽车… 相似文献
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本文介绍了电站高温高压阀门密封面采用氧乙炔焰加熔剂助熔一步法喷熔Fe547B合金粉末的新工艺。该法用于电站锅炉向空排气阀、安全阀等阀门密封面可提高使用寿命,打破了目前电站高温高压阀门密封面不能采用氧乙炔喷熔铁基材料的界线,在现场应用,具有一定的灵活性。 相似文献
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Si对Fe-18Cr-2Mo合金磁性的影响FeCr系磁性合金不仅耐蚀性优良,而且电阻率高,作为交流电磁器件使用具有优良的磁特性,在汽车电子式燃料喷射阀等方面已获实用。其烧结合金作为电磁阀门和汽车ABS传感器部件等将可获得更加广泛的应用。为了生产磁特性... 相似文献
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NiAl合金的高温形状记忆效应SCIEI 总被引:2,自引:0,他引:2
观察到Ni-34.6at.-%Al薄带单程和双程形状记忆效应(SME),单程SME发生在300℃以上并具有很好的形状恢复率(100%)。经高温退火后合金中产生了体积分数为16%的延性γ′-Ni_3Al沉淀相、延性和韧性有进一步改善,同时发现退火后的薄带也具有良好的单程和双程高温SME。结果表明富Ni的NiAl有可能成为新型高温形状记忆合金(SMA)。 相似文献
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研究了GH984合金在各种不同条件的抗腐蚀 性能.结果表明,该合金在700℃、800℃和900℃具有良好抗氧化能力,在不同热处理条件 及焊接状态下的抗晶间腐蚀、抗海水腐蚀性能良好,均能满足高速舰船的使用要求.在模拟 舰船发动机海上运行环境下,合金抗海洋性气氛燃气热腐蚀性能在900℃比GH135合金好,与 GH140合金相当,由于合金Cr含量较高,远优于镍基高温合金K3. 相似文献
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高贵宝 《锻压装备与制造技术》2017,52(4)
通过介绍发动机气门毛坯成形原理,分析了气门毛坯的缺陷及成因,论证了气门毛坯数字化电镦控制的气液控制系统的特点及原理。实验验证了数控系统参数优化的调整对毛坯质量的影响。 相似文献
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Florian Hauck Daniel Wendt Sebastian Stühle Emilia Kawa Hermann Wendt Wiebke Müller Matthias Thielmann Brigitte Kipfmüller Bernd Vogel Heinz Jakob 《Journal of Materials Engineering and Performance》2009,18(5-6):463-469
The use of percutaneous aortic valve implantation is limited, as the native calcified valve is left in situ. A new device has been developed for resecting calcified aortic valves, using collapsible nickel-titanium blades: laser-cut T-structures of Nitinol sheet-material (Ni51Ti49 at.%) have been grinded on a high-speed milling cutter to produce cutting edges which have been given the shape of half-circles afterwards. These have been connected to each other and to struts by using rivets which also serve as articulating axes for the cutting ring. The blades are folded around these axes and retreated into a tube to be inserted in the heart through the calcified valve leaflets. Once released, the cutting edges regain their ring-shape. By combining rotation of the ring with a translating movement against a second ring of slightly greater diameter on the instrument, a punching process is created which cuts the calcified valve leaflets and leaves a circular annulus, where a prosthesis can be fixed. In vitro cutting of artificially calcified valves (n = 6) resulted in a resection time of t = 22 ± 6.29 s with a maximum turning moment of M = 2.4 ± 1.27 Nm, proving the function and the feasibility of the concept. 相似文献
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针对汽车起重机克服反向负载时,升降油缸易出现爬行、低频抖动等现象,研究了一种汽车起重机变幅系统的平衡阀结构,建立了平衡阀的数学模型,通过AMEsim软件进行了仿真分析,分析了平衡阀控制特性、负载-流量特性、控制腔压力阶跃上升/下降响应和抑制负载波动响应。做了平衡阀台架试验,试验数据与仿真数据相比得到,数值误差较小,平衡阀开闭特性、过补偿能力和微动特性较好,平衡阀抗干扰能力、对负载波动抑制能力有待进一步改善。 相似文献
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A. Czechowicz K. Lygin S. Langbein 《Journal of Materials Engineering and Performance》2014,23(7):2687-2695
Shape memory alloys (SMA) can be utilized as thermal and electrical-activated drives for valve applications. By using the high actuation forces and medium strokes in combination with SMA intrinsic sensor functions, smart and versatile valve elements for multi-purpose applications can be designed. The sensoric functions, based on the change of the electrical characteristics of the SMA drive, allow to detect the system’s condition as well as the system’s fatigue. The paper systematizes the usability of the intrinsic sensor function with particular emphasis on service potentials. A methodical overview over the design-options of different applications is presented in the first part of the publications. This is followed by a methodical analysis of the potentials of SMA in service applications. Since the product development process is not only a mechanical engineering matter, the production and the service options according to such valves have to be regarded. Besides this publication presents an innovative production process based on a fused deposition production process (FDPP) of valves which contains the installation of SMA actuators during production. The publications present several demonstrator systems which have been produced with FDPP and analyzed in applications. 相似文献