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激光熔覆Ni基SiC合金涂层组织与性能的研究 总被引:5,自引:0,他引:5
利用5kWCO2连续波激光器在16Mn钢基材表面对含20%(体积比)SiC陶瓷粉末的镍基自熔性合金粉末进行激光熔覆得到Ni基SiC合金涂层(NiSiC)。研究了合金涂层的组织形貌及相结构,并用单纯的镍基合金涂层(Ni60)进行了显微硬度及滑动磨损性能的对比试验。结果表明,NiSiC合金涂层由γ枝晶及其间的共晶组织组成,主要组成相为γ-Ni,γ-(Ni,Fe)固溶体和(Cr,Fe)7C3,Cr23C6及(Cr,Si)3Ni3Si等化合物。添加SiC的镍基合金涂层NiSiC比单纯的镍基合金涂层Ni60具有较高的硬度和耐磨性。 相似文献
3.
Abdelbaki Benamor Brahim Si Ali Mohamed Kheireddine Aroua 《Korean Journal of Chemical Engineering》2008,25(3):451-460
The absorption rates of CO2 into aqueous solutions of Diethanolamine (DEA) with varying concentrations from 0.2 to 4M and temperature range from 293
to 323 K were measured by using a laboratory stirred reactor. The CO2 partial pressure was varied in a range that the reaction would occur in pseudo first order regime. Experimental data were
analyzed and the kinetic parameters associated with the reaction were determined. The activation energy for the deprotonation
of the intermediate zwitterion was estimated at about 11.4 kcal/mol. The contribution of carbamate formation to the overall
absorbed CO2 was experimentally evaluated and found to be of the order of 100%. 相似文献
4.
Mutual information-based analysis of JPEG2000 contexts. 总被引:4,自引:0,他引:4
Context-based arithmetic coding has been widely adopted in image and video compression and is a key component of the new JPEG2000 image compression standard. In this paper, the contexts used in JPEG2000 are analyzed using the mutual information, which is closely related to the compression performance. We first show that, when combining the contexts, the mutual information between the contexts and the encoded data will decrease unless the conditional probability distributions of the combined contexts are the same. Given I, the initial number of contexts, and F, the final desired number of contexts, there are S(I, F) possible context classification schemes where S(I, F) is called the Stirling number of the second kind. The optimal classification scheme is the one that gives the maximum mutual information. Instead of using an exhaustive search, the optimal classification scheme can be obtained through a modified generalized Lloyd algorithm with the relative entropy as the distortion metric. For binary arithmetic coding, the search complexity can be reduced by using dynamic programming. Our experimental results show that the JPEG2000 contexts capture the correlations among the wavelet coefficients very well. At the same time, the number of contexts used as part of the standard can be reduced without loss in the coding performance. 相似文献
5.
R Levy F Najioullah B Keppi D Thouvenot S Bosshard J Lornage B Lina JF Guerin M Aymard 《Canadian Metallurgical Quarterly》1997,68(5):820-825
This paper presents the results of in vivo measurements on a worker from a fuel reprocessing plant who was involved in an actinide intake. The results revealed that false indications of an actinide lung burden could arise from a contaminant present elsewhere in the chest region. Consequently, it is important that lung monitoring programs for occupational workers handling actinides are conducted with this caution in mind and that due consideration is given even in cases of minor cuts/wounds in order to rule out substantial overestimation of internal radiation doses. 相似文献
6.
斯新中 《石油化工设备技术》1996,17(4):1-3
根据十万立方米浮顶油罐罐壁板应力测试的实测结果,运用应力分析程序,对罐壁板应力分布情况进行了分析和比较,通过调整罐壁板的厚度,使新设计储罐的罐壁板应力分布更加均匀、合理。 相似文献
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Jun Xiang Ge Si Fan Li Yi Yuan Chen 《Journal of Infrared, Millimeter and Terahertz Waves》1991,12(7):811-818
In this paper, a new kind of solid-state quasi-optical power combiner is presented. It consists of two or more singlecavity multiple-device power combiners and a Fabry-Perot cavity. The experimenal results using six Gunn diodes at X-band show that the total output power is higher than 400 mW, the total combining efficiency is as high as 83%, and the frequency stability is better than 10?5. 相似文献