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利用废旧辊环,通过重熔和离心铸造法制备了再生复合材料辊环,重点研究了离心机转速为800r/min和1000r/min时制备的再生复合材料辊环的组织和性能。样品的微观组织检测表明:再生复合材料辊环由WC颗粒大量分布的外层和Fe-C合金内层组成,离心机转速高的外层内WC增强颗粒体积分数较大。力学性能测试表明:800r/min转速下制备的再生复合材料辊环,其外层和内层的硬度分别达到HRC49、HRC42,冲击韧性分别为3.1J/cm2、5.1J/cm2。离心机转速提高到1000r/min时,外层和内层的硬度分别增加达到HRC58、HRC49,冲击韧性分别降低为2.3J/cm2、4.1J/cm2。 相似文献
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Precursor pastes were obtained by milling Cu-In alloys and Se powders. CuInSe2 thin films were successfully prepared by precursor layers, which were coated using these pastes, and were annealed in a H2 atmosphere. The pastes were tested by laser particle diameter analyzer, si- multaneous thermogravimetric and differential thermal analysis instruments (TG-DTA), and X-ray diffractometry (XRD). Selenized films were characterized by XRD, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results indicate that chal- copyrite CuInSe2 is formed at 180°C and the crystallinity of this phase is improved as the temperature rises. All the CuInSe2 thin films, which were annealed at various temperatures, exhibit the preferred orientation along the (112) plane. The compression of precursor layers before selenization step is one of the most essential factors for the preparation of perfect CuInSe2 thin films. 相似文献
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用粉末涂敷法在Mo箔上涂敷CuInSe2前驱体薄膜,进而在H2气氛中热处理制备了太阳能薄膜电池吸收层用CuInSe2薄膜.利用X射线衍射仪(XRD)、扫描电镜(SEM)和其配备的能谱仪(EDS)对CuInSe2薄膜进行分析和表征,对硒化烧结过程中化学反应的可能性进行了热力学计算.结果表明:硒化烧结过程分为三个阶段:二元化合物CuSe和三元化合物CuInSe2的形成均出现在硒化烧结的前两个阶段;第三个阶段主要是CuInSe2晶粒长大和薄膜的致密化过程.H2气氛在CuInSe2薄膜烧结过程中可能起到催化剂的作用. 相似文献
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Shiju Joseph Shashank Bishnoi Koen Van Balen Özlem Cizer 《Journal of the American Ceramic Society》2018,101(6):2438-2449
Effect of water to cement (w/c) ratio and temperature profiles on the densification of C–S–H (calcium silicate hydrate gel) and hydration kinetics of triclinic tricalcium silicate (C3S) is studied beyond the first day of hydration. Calorimetry and quantitative X‐ray diffraction/Rietveld analysis show that degree of hydration is unaffected by w/c up to 7 days and marginally thereafter. Coupling the degree of hydration with the portlandite content measured from thermal analysis indicate that C/S ratio of C–S–H decreases with increasing w/c. There is a clear increase in the portlandite content with increasing w/c, even though the degree of hydration is unchanged, due to the variations in C/S ratio of C–S–H. On the other hand, when C3S is initially cured at a lower temperature (20°C) and then at a higher temperature (40°C), there is a significant increase in the reactivity even until 28 days and vice versa. These experimental results were explained using the densified volumetric growth hypothesis, which assumes that hydration kinetics are dependent on the internal surface area of C–S–H. 相似文献
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Shiju Joseph Shashank Bishnoi Koen Van Balen Özlem Cizer 《Journal of the American Ceramic Society》2017,100(3):1178-1194
Alite (impure C3S) being the major and most reactive phase in ordinary portland cement has been studied extensively. This paper focuses on the mathematical modeling of new hypothesis developed, densified volumetric growth, applied to the main hydration peak in alite hydration. This hypothesis assumes a time and particle size‐dependent growth rate and densification rate of C–S–H controlled by its internal surface area. To test this hypothesis, a new microstructural modeling platform (Cementitious Reactions Simulator) has been developed. The model was used to calibrate and predict the isothermal calorimetric results from the literature and two sets of original experimental results with alite replaced with different replacement fractions of quartz, fly ash, and slag of different fineness. The model is able to capture and predict the effect of fineness and fillers without the need of varying the parameters for the particular set of simulations. The values of the parameters of simulation reflect the current experimental evidence from the literature and thus provide validation of the hypothesis which suggests that the main hydration period including deceleration period in the alite hydration is induced by the densification and reducing outer growth rate of C–S–H. 相似文献