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汽车半轴中频感应淬火的质量实时控制 总被引:1,自引:0,他引:1
利用RAYTEK红外测温仪测量了汽车半轴中频感应淬火时不同电参数情况下的表面温升曲线.并对有效硬化层深、过渡区层深、表面硬度变化以及金相组织进行了研究.得到了性能随电参数变化的规律.把所有金相以及硬度和层深分布都合格的样品与淬火时实时测量的表面温升曲线相对应,得到了质量合格区.从而实现了用测温仪在线实时控制,当温升曲线进入合格区时即可停止加热并立即淬火. 相似文献
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《理化检验(物理分册)》2015,(10)
垂直磁记录薄膜可以通过Delta-M曲线来判断其磁性晶粒间相互作用等相关磁性能。采用Lakeshore7407型振动样品磁强计(VSM)测量了直流磁控溅射制备的Co23Pt77垂直磁记录薄膜的磁性能,详细介绍了垂直薄膜等温剩磁(IRM)曲线和直流退磁剩磁(DCD)曲线的测量方法及退磁因子的计算方法,确定了退磁场修正方法并讨论了如何根据退磁场修正后的IRM曲线和DCD曲线得到垂直磁记录薄膜的Delta-M曲线。 相似文献
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用溶胶一凝胶方法制备了纳米多晶La0.7Sr0.3MnO3样品.测量了不同温度下烧结的样品的零场冷却交流磁化率与温度和直流磁场的依赖关系.通过对铁磁-顺磁转变点附近临界峰的分析,得到973K烧结的多晶样品居里温度为312.1K±0.2K,临界指数为:δ=3.040,γ=1.007,β=0.493;1173K烧结的多晶样品居里温度为331.7K±0.1K,临界指数分别为:δ=2.950,γ=0.993,β=0.508.两组数据均与平均场理论预言结果一致,表明纳米多晶La0.7Sr0.3MnO3样品在磁性相变点附近存在长程相互作用. 相似文献
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介绍了采用微电脑控制的小样品升降温控制装置,测量了小样品在过冷氟里昂R12和R22的淬冷过程。得到了沸滕冷却曲线以及平均对流换热系数和沉浸速度之间的拟合公式,并讨论了提高小样品冷却速率的方法。 相似文献
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采用Gleeble-3500热模拟试验机测量了10CrNi5MoV钢焊缝金属在不同冷却速率下奥氏体连续冷却过程中的温度-膨胀曲线,利用杠杆定律,得到了不同冷却速率下相变动力学曲线,分析了冷却速率对焊缝金属相变的影响。结果表明,不同冷却速率下焊缝金属的奥氏体转变动力学曲线均呈S型,冷却速率为60 ℃/s、30 ℃/s、15 ℃/s时,奥氏体转变速率与温度的曲线呈单峰状,冷却速率为6 ℃/s,奥氏体转变速率与温度的曲线表现为贝氏体、粒状贝氏体相变的双峰转变。 相似文献
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Hengsong Zhang Fulin Zuo Di Wu Jing Shi 《Journal of Superconductivity and Novel Magnetism》2010,23(6):1043-1045
We report magnetic studies of the paramagnetic effect observed in the superconducting nano-structured opal-lead system. Positive
magnetization is clearly observed when the sample is cooled in field. The paramagnetic effect is strongly dependent on the
applied field and the cooling rate. The results suggest that the paramagnetic moment is due to flux trapping and the competition
between the positive and negative moments due to the temperature dependence of the penetration depth. 相似文献
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氨制冷装置用蒸发式冷凝器的实际能耗研究 总被引:1,自引:0,他引:1
理论上,蒸发式冷凝器的循环水量小于水冷式冷凝器的10%,因而采用蒸发式冷凝器更加节能。针对不同品牌的蒸发式冷凝器和水冷式冷凝器两种类型的典型产品,对能耗进行了理论计算、产品选型计算和现场测试比较分析。结果表明,蒸发式冷凝器单位排热量能耗的理论计算值、产品选型值和实际运行值差别不大。产品选型中,在相同的排热量下选用不同典型品牌的蒸发式冷凝器,能耗差异很大,如B品牌蒸发式冷凝器的平均能耗约为A品牌平均能耗的2倍。根据实际运行测试,三种典型品牌蒸发式冷凝器的平均能耗约为立式水冷式冷凝器系统的32%,约为卧式水冷式的47%。 相似文献
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研制了中国首台高温超导磁储能直接冷却系统,该系统不使用低温液体(液氦、液氮).在10-3Pa的真空度下,高温超导磁体线圈由1台单级GM制冷机从室温293 K冷却到19 K,Bi2223电流引线由另一台制冷机冷却到77 K以下.整个系统在通140 A直流电流的时候产生了4.5 T的磁场.系统连续运行480 h(20 d),磁体和低温系统各参数动态特性良好.实验研究表明,控制系统的漏热,优化磁体内部导冷结构,有效减少热传导部件的接触界面热阻是制冷机直接冷却高温超导磁体的关键技术. 相似文献
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We have studied the magnetic properties of aggregates of Mn0.5Zn0.5Gd(x)Fe(2-x)O4 ferrite nanoparticles, with x = 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.18, 0.20. The scanning electron microscopy micrographs show significant aggregation of the nanoparticles in all samples. Zero field cooled and field cooled magnetization measurements were conducted on all samples from 400 K down to 5 K. Most zero field cooled curves were found to exhibit the usual behavior but with wide peaked regions. For some x values, the field cooled magnetization was found to increase slowly with decreasing temperature, and becomes nearly constant at low temperatures. The measurements of magnetization versus applied magnetic field were conducted on all samples at 5 K and 305 K in the field range from -15000 to 15000 Oe. At 305 K the magnetization for all samples was observed to saturate, while at 5 K the magnetization did not reach saturation for some values of x. The saturation magnetization values were suggested to be proportional to the size of particles. These results were discussed and suggested to be due to the inter-particle dipolar and exchange interactions between the particles in the aggregates, the large particle size distribution and the surface magnetization effects. 相似文献
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S. Reich G. Leitus R. Popovitz-Biro A. Goldbourt S. Vega 《Journal of Superconductivity and Novel Magnetism》2009,22(4):343-346
Magnetic susceptibility measurements of WO3 crystals hydrogen doped on the surface suggest 2D local non-percolated superconductivity with an onset temperature of 120 K.
Observed zero field cooled vs. field cooled magnetization response is characteristic of type II superconductivity. The diamagnetic
response at the critical temperature is field dependent, and is suppressed by a magnetic field of ∼1700 Oe. 相似文献
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Effects of Bismuth Doping on the Physical Properties of La0.6−x
Bi
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Sr0.4CoO3 (0≤x≤0.15) Cobaltites
F. Saadaoui M. Koubaa W. Cheikhrouhou-Koubaa A. Cheikhrouhou 《Journal of Superconductivity and Novel Magnetism》2013,26(10):3043-3047
The structural and magnetic properties of cobaltites with the nominal composition La0.6?x Bi x Sr0.4CoO3 (0≤x≤0.15) have been investigated. X-ray diffraction analysis using Rietveld refinement show that all our samples crystallize in the rhombohedral structure. The zero field cooled (ZFC) and field cooled (FC) magnetization curves at 50 mT exhibits thermomagnetic irreversibility signature of short range ferromagnetic interactions in our samples. The ferromagnetic–paramagnetic transition temperature decreases with increasing Bi amount. In the paramagnetic phase, all our synthesized samples obey to the Curie–Weiss law. The Curie–Weiss analysis suggests that the spin state of Co3+ is IS while Co4+ ions are in IS for x=0 and LS for x≥0.05. The Bi doping also leads to a weakening in the magnetic moment. The magnetic entropy change exhibits a maximum value which decreases from 2.28 J/kg?K for x=0 to 1.24 J/kg?K for x=0.15 upon a magnetic field change of 5 T. 相似文献
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The basic design principles of current leads for superconducting magnets are well established but HTS materials and conduction cooled systems call for new numerical methods. In this paper the design of current leads was formulated as an optimization problem. Both time integration and finite differencing were examined as possible ways to compute the temperature distribution inside the leads. Three examples about optimization of conduction cooled as well as gas cooled systems are presented. First, the design of tubular normal conducting gas cooled current leads was studied. Second, normal conducting leads cooled with a two-stage cryocooler were examined. Third, the optimization was applied to current leads consisting of HTS tapes at the low temperature end of a normal conducting bar. The study took into account the magnetic field and temperature dependent voltage-current characteristics of the anisotropic Bi-2223 material. The results are compared with traditional analytical ones and the numerical optimization is shown to be an efficient design tool for both normal conducting and HTS current leads. 相似文献
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The features characteristic of boiling of emulsions with a low-boiling dispersed phase are studied. The phenomenon of chain
boiling up of droplets of the dispersed phase is considered. The dependence of the moment of emergence of chain activation
of boiling sites and the subsequent chain boiling up of droplets of the dispersed phase on the temperature of the surface
being heated (cooled) is obtained. 相似文献
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Magnetic measurements have been performed on FeAs single crystals and polycrystalline samples. Magnetic measurements revealed a very sharp spin-glass magnetic transition in self flux grown single crystal. The bifurcation point between zero field cooled (ZFC) and field cooled (FC) magnetization occurs at 130 K. Susceptibility of flux grown single crystals revealed ferromagnetic-type behavior in the temperature range 4–300 K, while single crystals grown by iodine transport vapor were non-magnetic revealed features associated with antiferromagnetic and spin wave characteristics. The shift in Raman lines reveled sharper peaks for the crystals grown by vapor transport method than that obtained for the flux grown crystals. The difference in the spectrum may indicate sharper distribution in the bonding strength between Fe and As ions in crystals grown by the iodine vapor transport method. 相似文献