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61.
REHEATING TEMPERATURE CONTRAST AND MICROSTRUCTURES OF 7075 Al ALLOY CAST BY LIQUIDUS SEMI-CONTINUOUS CASTING 总被引:4,自引:0,他引:4
J. Dong G.M. Lu J.Z. CuiThe Key Lab. of Electromagnetic Processing of Material Ministry of Education Northeastern University Shenvane China 《金属学报(英文版)》2002,(6)
In this study, reheating of liquidus semi-continuous cast billets of 7075 Al alloy was carried out in a resistance furnace, and the temperature contrast of the outer and the center of the reheated billets was investigated, then the reheating microstructures were investigated. Results show that: the difference of temperature between the outer and center is small and the difference of their microstructures are also small. During reheating at 576℃ the spheroidization of grains is significant after 5min and no rosettes are visible after 20min by optical microscopy. Similar observations were madeon materials reheated at 596℃, but the ripening process is faster. The grains growup to 30-60μm, fine enough for thixoforming. 相似文献
62.
63.
电子镇流器用高压长寿命铝电解电容器 总被引:2,自引:2,他引:0
铝电解电容器是节能灯用电子镇流器的关键元件,由于镇流器的工作环境严酷,其电容器最易失效。改进后的CD11H系列电子镇流器用铝电解电容器标准突出了105℃下满负荷工作3000h的高可靠性要求。设计目标放在延长寿命,提高可靠性,减少失效率方面。选用电容器时要注意工作电压、上限工作温度、耐久性。 相似文献
64.
傅文祖 《有色金属材料与工程》1994,15(5):300-307
连续挤压法的特点是:挤压所需的压力是借助一个回转的摩擦轮来实现的。摩擦轮的轮缘上设有一个凹槽,其断面取决于原坯的断面(线材坯料)。本文将就这种工艺的设备和有关铝材生产阶段中的一些问题作一简介。 相似文献
65.
G. Coudenys I. Moeeman G. Vermeire F. Vermaerke Y. Zhu P. Van Daele P. Demeester E. Maayan B. Elsner J. Salzman E. Finkman 《Journal of Electronic Materials》1994,23(2):225-232
The shadow masked growth technique is presented as a tool to achieve thickness and bandgap variations laterally over the substrate
during metalorganic vapor phase epitaxy. Lateral thickness and bandgap variations are very important for the fabrication of
photonic integrated circuits, where several passive and active optical components need to be integrated on the same substrate.
Several aspects of the shadow masked growth are characterized for InP based materials as well as for GaAs based materials.
Thickness reductions are studied as a function of the mask dimensions, the reactor pressure, the orientation of the masked
channels and the undercutting of the mask. The thickness reduction is strongly influenced by the mask dimensions and the reactor
pressure, while the influence of the orientation of the channels and the amount of undercutting is only significant for narrow
mask windows. During shadow masked growth, there are not only thickness variations but also compositional variations. Therefore,
we studied the changes in In/Ga and As/P ratios for InGaAs and InGaAsP layers. It appears that mainly the In/Ga-ratio is responsible
for compositional changes and that the As/P-ratio remains unchanged during shadow masked growth. 相似文献
66.
针对10#高炉炉渣中Al2O3高的特性,通过对炉渣性能的分析,调整操作制度,改善炉渣性能,加强炉前管理等,使10#高炉生产水平明显提高. 相似文献
67.
38MnSiVS5 steel is similar to 38MnVS6 steel (EN), the difference being the addition of a small Ti content. Typical Ti and Al contents in the chemical composition of 38MnSiVS5 steel are Ti=0.020 and Al=0.035 mass%. Both elements combine easily with nitrogen, especially Ti, and it has been observed that relatively high Al levels are harmful for austenite grain size control at reheating temperatures. In this work 38MnSiVS5 steel is used to manufacture a large number of castings, varying only the Ti and Al contents and obtaining ingots with a different Ti/Al ratio in each case. The results show that abnormal growth of the austenitic grain occurs irrespective of the Ti and Al contents, due fundamentally to the partial dissolution and coarsening of TiN precipitates. However, the steels with high Al contents present worse behaviour due to the formation of a second type of precipitates, namely AIN, which quickly dissolve between 1000 and 1100°C, causing a drastic decline in local pinning forces that gives rise to more pronounced abnormal growth of the affected grains. 相似文献
68.
69.
低价硫化铝法从氧化铝直接炭还原制铝的动力学研究 总被引:3,自引:0,他引:3
低价硫化铝法从氧化铝直接炭还原制铝的动力学过程极为复杂,过程的前期受界面化学反应控制,过程后期受扩散过程控制,并求得不同时期的活化能,反应前期:E1=63.81 kJ/mol(6.67 Pa)、E2=50.82 kJ/mol(66.7 Pa)、E3=54.72 kJ/mol(666.7 Pa)、E4=39.61 kJ/mol(1333 Pa);反应后期:E*1=112.90 kJ/mol(6.67 Pa)、E*2=89.92 kJ/mol(66.7 Pa)、E*3=97.32 kJ/mol(666.7 Pa)、E*4=51.83 kJ/mol(1333 Pa).从动力学的角度提出了反应的较佳条件.温度、真空度的提高一方面可增大反应速率,但另一方面却加大了硫化铝的挥发,仅从增大速率而言,温度应大于1100 ℃,真空度应优于1333 Pa为宜. 相似文献
70.
Hamdy F. M. Mohamed 《应用聚合物科学杂志》2008,108(2):1307-1313
Coincidence Doppler broadening of annihilation radiation (CDBAR) and Vickers hardness techniques were performed to study pure Al2O3, pure polyvinyl chloride (PVC), and doped PVC with different concentrations of Al2O3 (10–50%). The CDBAR ratio curves with respect to pure PVC were presented and reflect the momentum distribution of all the samples. The peak around 14.5 ×10?3 moC in the CDBAR ratio curves suggests a large contribution of positron annihilation with the Al2O3. There is a linear correlation between the height of this peak and the Al2O3 concentration. The S‐ and W‐parameters were extracted from the CDBAR spectra and increase with increasing the Al2O3 concentration showing discontinuity at 30% of Al2O3 concentration on PVC. The present data confirmed that there is no positronium formation in pure Al2O3 as a result of smaller S‐parameter. The Vickers hardness increases with increasing the Al2O3 concentration in PVC showing a linear dependence with two different slopes depend on the Al2O3 concentration range. A correlation between the Vickers hardness (macroscopic data) and the W‐parameter (microscopic data) was observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献