共查询到20条相似文献,搜索用时 81 毫秒
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本文主要研究了石粉对水泥-矿粉混凝土的工作性、抗压强度、耐久性能(抗渗性能、抗碳化性能和抗冻性能)的影响,并利用孔结构微观分析对其进行了机理分析。研究表明:石粉应用于水泥-矿粉混凝土中,不仅可改善混凝土的工作性能,而且可提高混凝土的抗压强度,对混凝土的耐久性能(抗渗性能、抗碳化性能和抗冻性能)影响不大。 相似文献
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碳纳米管增强高聚物功能复合材料研究进展 总被引:1,自引:0,他引:1
介绍了碳纳米管的结构、性能及其表面改性.综述了碳纳米管增强高聚物在导电性能、微波吸收性能、光学性能及导热性能等方面的研究进展.提出了碳纳米管增强高聚物功能复合材料研究过程中面临的一些问题,并展望了这类复合材料的应用前景. 相似文献
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脉石英矿制备高纯石英砂工艺的试验研究 总被引:1,自引:0,他引:1
为了使天然脉石英达到高纯石英砂的标准,通过煅烧—水淬—浮选—酸洗—乙醇-去离子水洗等工艺提纯石英砂,采用光学显微镜、扫描电镜、X射线衍射、激光粒度仪、电感耦合等离子体光谱仪等手段分析石英砂试样的显微结构、形貌、物相、粒度和成分。结果表明,脉石英矿粗砂粒径分布较均匀,浮选精砂及高温煅烧精砂的粒径明显增大,比表面积明显减小;浮选后精砂的大颗粒为纯石英;筛分、高温处理对石英砂杂质元素去除不明显,浮选、酸浸去除杂质效果显著,脉石英矿经处理后的石英砂中SiO2的质量分数达到99.99%以上。 相似文献
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A near backscattered laser Doppler system was presented to carry out velocity and size distribution measurements for irregular particles in two-phase flows. The technique uses amplitudes of particles Doppler signals to estimate the particle size distribution in a statistical manner. Holve's numerical inversion scheme is employed to unfold the dependence of the scattered signals on both particle trajectory and orientation through the measurement volume. The performance and error level of the technique were simulated, and several parameters including the number of particle samples, the fluctuation of irregular particle response function, inversion algorithms, and types of particle size distribution were extensively investigated. The results show that the size distributions for those irregular particles even with strong fluctuations in response function can be successfully reconstructed with an acceptable error level using a Phillips-Twomey-non-negative least-squares algorithm instead of a non-negative least-squares one. The measurement system was then further experimentally verified with irregular quartz sands. Using inversion matrix obtained from the calibration experiment, the average measurement error for the mixing quartz sands with a size range of 200-560 microm are found to be about 23.3%, which shows the reliability of the technique and the potential for it to be applied to industrial measurement. 相似文献
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采用电石渣对石英岩尾砂进行煅烧改性,利用X射线衍射仪、背散射扫描电镜和能谱分析等方法对改性石英岩尾砂矿物组成和微观结构进行表征,并研究了改性石英岩尾砂的水化性能。通过背散射扫描电镜和压汞仪分析了掺改性石英岩尾砂水泥浆体的微界面结构与孔结构。结果表明:改性石英岩尾砂具有复合结构,内部是惰性的石英岩尾砂,表层为矿物β-C2S层。改性石英岩尾砂可水化生成C-S-H凝胶,改善了石英岩尾砂与水泥浆体的微界面,降低了水泥浆体的孔隙率。 相似文献
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采用湿法混合工艺制备了短切石英纤维增强的PMR 型聚酰亚胺复合材料模塑粉, 使用热模压一次成型技术制备了聚酰亚胺树脂基复合材料, 对复合材料的性能进行了系统研究。研究结果表明: 短切石英纤维增强的复合材料具有优异的热性能和良好的力学性能, 纤维含量对复合材料玻璃化转变温度和热失重温度影响不大,对材料的力学性能影响显著。复合材料具有优异的介电性能, 在1 kHz~18 GHz 宽频范围内具有稳定的介电常数和介电损耗。 相似文献
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Yun-Jong Kim Sang-Bae Kim Hyun-Hye Park Myeong-Deok Seo Byoung-Cheon Lee Man-So Han Taik-Nam Kim Sung-Baek Cho 《材料科学技术学报》2008,24(1):143-144
Generally the gold investment material consists of cristobalite,quartz and plaster.The physical property of gold investment materials depends on its thermal expansion coefficients,compressive strength,and particles size distribution.Since the thermal expansion coefficient of cristobalite and quartz are 2.6×10^-6/℃and 2.32×10^-6/℃respectively,the composition ratio of each components influence the thermal and physical properties of gold investment materials.For the clinical applications,it is necessary to improve the properties of gold investment materials such as homogeneous size distribution and thermal expansion coefficients.In the present study,effect of inorganic fillers such as cristobalite and quartz on gold alloy investment was investigated to improve the properties of it.The compressive strength and thermal expansion coefficients of the specimens were evaluated.The results showed that cristobalite and quartz were homogeneously distributed by milling. The optimum compressive strength was obtained at the ratio of 42:22 cristobalite and quartz,respectively. 相似文献
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《IEEE transactions on instrumentation and measurement》1975,24(1):21-26
For years, engineers and scientists have been plagued by an extremely undesirable property of the quartz crystal unit-its significant frequency shift as a function of drive level for drive levels in excess of 10 to 100 ?W. This fact was reported by Hammond [1]. As a result, all precision and moderate precision quartz oscillators have been operated at low drive in an effort to avoid the phenomena. The author has discovered, however, that this unique property of the quartz resonator can be effectively utilized in the design of the quartz oscillator with the result of substantial improvement in oscillator short-term frequency stability. Futhermore, since the crystal frequency-drive characteristic is repeatable, maintenance of moderately high crystal drive in the oscillator circuit will not result in long-term frequency instability in excess of that required for the majority of radar and communication systems [2]. 相似文献
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Despite the fact that the maximum content of fines in aggregates is restricted in national and international standards, the
use of unwashed sands in restoration mortars is often demanded by restorers due to their colouring properties. The colour
of these aggregates may be caused by clay minerals in the fine fraction below 63 μm. Hence, this study aims to determine the
influence of loam and clay contents in a quartz aggregate on the properties of fresh and hardened lime- and lime-cement-mortars.
The experimental results revealed that the main effect of clay fines in aggregates is an increase of the water demand for
a constant mortar consistency. As a consequence, the higher water/binder ratio causes a strong decrease of the mortar quality
with respect to mechanical, hygral and durability properties. 相似文献