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101.
Jingjie Guo Jun Jia Hengzhi Fu Guizhong Liu Yanqing Su Hongsheng Ding 《Metallurgical and Materials Transactions A》2002,33(10):3249-3253
In this article, two key pressures, the critical pressure P
crit and the impeding pressure P
impe of elemental evaporation, are defined and studied based on the calculation relationship between the evaporation loss rate
N
m and the chamber pressure P during melting of titanium-aluminum alloys. When the chamber pressure is below P
crit or above P
impe, N
m tends to the maximum or the minimum value and remains almost unchanged. However, if P
crit<P<P
impe, with the increase of the chamber pressure, N
m declines sharply. A method has been put forward to calculate P
crit and P
impe of Al evaporation in a Ti-XAl (at pct) (X=25 to 50) melt. The calculation result shows that P
crit or P
impe is a second-order function of the molar percentage of Al and the melt temperature. 相似文献
102.
In order to develop a basic electrode with low fume and good usability, a uew slag system has been designed after analyzing several basic electrode slag systems. Then in view of uniform design method, arranging the experiment points by it, the influenced laws of the uew system coating compouents on the arc stability had been searched. In the formula, niue coating compouents were taken as independent variables and they were divided into six levels in all twenty-four experiments. The arc stability was taken as function and taken down the data when welding and then put them into the computer to be processed statistically. The analysis results give the mathematical model and trend diagrams between independent variables and the function. They indicate that the effects of many coating compouents on the arc stability are in the mutual form. The mutual effects between CaCO3 and BaF2, BaF2 and BaCO3 , increases the arc stability separately. While the mutual effects between CaF2 and iron powder, the square item of iron powder itself decreases the arc stability separately. 相似文献
103.
104.
本文探讨了高速钢在高温形变过程中碳化物析出的行为及奥氏体组织状态对析出的影响。用透射电镜和扫描电镜分析了不同热处理状态奥氏体的组织结构,分析了高温形变过程中碳化物析出的部位,颗粒尺寸及形态。试验表明, 碳化物主要在奥氏体的缺陷处呈点状和点列状析出,大小为20mμ。处于回复状态的奥氏体缺陷诱发碳化物析出,析出碳化物钉札缺陷阻止再结晶进行。当再结晶驱动力较大时,由于动态再结晶充分发展,使缺陷大量消除,碳化物析出显著地减少。 相似文献
105.
《钢铁研究学报(英文版)》2006
Being a new permanent magnets(PMs) arrangement, the Halbach array could approve the magnetic flux density effectively, through weakening the magnetic flux density in one side of the PMs array, meanwhile strengthening the magnetic flux density in the other side. In the disk coreless PM synchronous motor (PMSM), the magnetic flux density is required to be sine wave and the peak value should be as high as possible. The paper deals with the application of the 90° Halbach array in the disk coreless PMSM, adopting NdFeB PMs. For the thickness of PMs influences the magnetic flux density in the air gap, the thickness variation technology is adopted. Through altering the adjacent PMs thickness, nine different PMs thickness combination is analyzed by FEM methods. And the conclusion is that when the thickness of tangential magnetization PMs is great than that of the radial magnetization PMs, the magnetic flux density wave is closer to sine wave than when the thickness of the tangential magnetization PMs is smaller than that of the radial magnetization PMs. Furthermore, when the thickness of the tangential magnetization PMs is great than that of the radial magnetization PMs, keeping the thickness of the tangential magnetization PMs being 0.006 m and the thickness of the radial magnetization PMs variation from 0.0048 m to 0.006 m, the magnetic flux density in the air gap will become closer to sine wave gradually, and then it becomes nonsinusoidal again. And when the thickness of radial magnetization PMs is 0.0054 m and 0.0055 m, the waves of magnetic flux density in the air gap are better than others. 相似文献
106.
《International Journal of Heat and Mass Transfer》2007,50(15-16):3250-3263
108.
《Materials Letters》2007,61(4-5):1109-1113
We report the synthesis of a nanostructured γ-LiAlO2 network in an Al-based metal matrix composite (MMC) by arc-melting a powder compact of Al–15 wt.%Li2O. During synthesis, chemical reactions between Al and Li2O occurred, and a two-phase Al-γ-LiAlO2 MMC was produced. The γ-LiAlO2 was in the form of nano-network extended evenly in the Al matrix. The apparent density and Vickers' hardness number of the MMC were determined to be 2.31 gcm− 3 and 143, respectively, and having a relative density of 0.87. The MMC was made nano-porous by etching away Al with a 2 M NaOH solution. The sizes of pores were about 150 nm and the width of the branches in the γ-LiAlO2 network was about 90 nm. Atomic force microscopy revealed that the branches were composed of fine grains of 50 nm in diameter. Microstructure of the network was not altered even after prolonged etching, and this suggested that γ-LiAlO2 was chemically inert to NaOH corrosion. Specific surface area of the γ-LiAlO2 nano-network was measured to be 79 m2/g, and its porosity was determined to be 43.7%. 相似文献
109.
110.
由于具有初曲率板弯曲问题的控制微分方程较复杂,直接求解原问题基本解推导边界积分方程较为困难。本文通过引入等效荷载,将此问题的控制微分方程化成与普通板弯曲基本方程形式相同的微分方程,利用一般求解板弯曲问题的边界元法迭代求解,建立了分析具有初曲率板弯曲问题的边界元法。算例表明本方法理论准确、精度良好。 相似文献