共查询到20条相似文献,搜索用时 62 毫秒
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介绍了固体粉末制备Al18B4O33(硼酸铝)晶须的新技术,用TEM确定了晶须的结构,用SEM观察了晶须的形貌,并分析讨论晶须形成机理和影响因素。 相似文献
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以稻壳为原料,利用不同催化剂合成了两类不同形貌特征的BP-SiC晶须,在WB催化剂作用下合成的SiC晶须表面粗糙,呈多节状;在WC复合催化剂作用下,SiC晶须表面光滑。运用TEM、XRD等分析检测技术,对SiC晶须的形貌结构、直径、长度、长径比等进行了分析,并同国外晶须进行了比较。此外,对BP-SiC晶须在先进复合材料中的应用进行了分析和预测。 相似文献
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基于滑移线场的SiCw/6061复合材料挤压变形晶须形貌分析 总被引:1,自引:1,他引:0
为探讨挤压变形对SiCw/6061复合材料晶须形貌的影响规律,首次引入塑性变形滑移线场理论对SiCw/6061复合材料的挤压过程进行研究。通过给出典型挤压工艺的正挤压实心件及反挤压杯形件的滑移线场及速端图,分析滑移线场以及速度间断对晶须形貌的影响,并与试验所得相应晶须形貌电镜照片进行对比。研究结果表明,最大切应力将引起SiC晶须沿滑移线切线方向的转动,导致晶须取向为其初始方向与滑移线方向的合矢量;速度间断所对应的沿滑移线切向的剧烈速度变化将导致位于速度间断线两侧的SiC晶须发生折断。 相似文献
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使用耐高温SPEEK偶联剂对碳酸钙晶须进行表面处理,利用热压成型方法制备质量分数为0~30%的碳酸钙晶须增强聚醚醚酮(PEEK)复合材料,在MM-200型磨损试验机上测试复合材料与45#钢环配副的摩擦磨损性能,利用扫描电子显微镜观察磨损表面形貌,分析磨损机制。结果表明,SPEEK偶联剂改善了晶须与PEEK基体的界面结合,提高晶须的力学增强效果,复合材料的减摩和耐磨性能显著提高。填充10%~25%晶须,复合材料具有较好的摩擦磨损性能。碳酸钙晶须提高了复合材料承载能力,减少摩擦副表面粘着,阻止树脂的热塑性变形,复合材料磨损以磨粒磨损和疲劳磨损为主。 相似文献
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采用国产SiC晶须制备SiCw-ZTA陶瓷基复合材料,研究了SiC晶须含量对复合材料的抗弯强度、断裂韧性和抗热震性能的影响,并分析了晶须增韧和ZrO2相变增韧两种机制协同作用的条件。 相似文献
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根据广州市珠江新城旅客自动运输系统(APM)列车的运行特点,介绍APM列车制动系统的制动方式及其特点,分析APM列车动态制动和摩擦制动的工作机理及其区别和联系,阐明APM列车制动系统的电控制过程和气控制过程,从而为APM列车制动系统的维护和管理提供一定的依据. 相似文献
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我公司于80年代末引进Aspera公司年产80万台冰箱(冷柜)压缩机生产线及软件技术,在压缩机加工中,活塞销孔(如图1所示)的加工是难点之一。用镗床加工,质量一直难以达到要求,废品率很高。后来我们将Aspera公司的加工工艺即精镗后滚光改为精镗后用金刚石铰刀粗、精铰孔,由此解决了这个技术难题。(1)原意大利Aspera公司工艺简述其工艺流程为:钻6.5通孔→扩孔至7+0.1→粗镗7.473+0.036、圆柱度0.01→精镗至7.935+0.006、圆柱度0.002→滚光7.938+0.006、圆柱度0… 相似文献
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In a recent paper, the Ritz method with simple algebraic polynomials as trial functions was used to obtain an eigenvalue equation for the free vibration of a class of homogeneous solids with cavities. The method presented is here extended to the study of a class of non-homogeneous solids, in which each solid is composed of a number of isotropic layers with different material properties. The Cartesian coordinate system is used to describe the geometry of the solid which is modelled by means of a segment bounded by the yz, zx and xy orthogonal coordinate planes and by two curved surfaces which are defined by fairly general polynomial expressions in the coordinates x, y and z. The surface representing the interface between two material layers in the solid is also described by a polynomial expression in the coordinates x, y and z. In order to demonstrate the accuracy of the approach, natural frequencies are given for both a two- and three-layered spherical shell and for a homogeneous hollow cylinder, as computed using the present approach, and are compared with those obtained using an exact solution. Results are then given for a number of two- and three-layered cylinders and, to demonstrate the versatility of the approach, natural frequencies are given for a five-layered cantilevered beam with a central circular hole as well as for a number of composite solids of more general shape. 相似文献
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所谓现代化的电梯是指电梯无论在结构上还是在特性、功能上都要满足人们对电梯提出的越来越高的要求 ,这其中包括①电梯的结构———采用先进的制造工艺及控制技术 ,使电梯的结构越来越紧凑、精巧、坚固、美观及实用 ;②电梯的运行性能———采用先进的自动控制理论、先进的传动与控制技术 ,使电梯在运行过程中具有安全可靠、快速、准确、平稳的特性 ,即使电梯具有良好的乘坐舒适感。而电梯运行过程中的振动 ,则是影响电梯乘坐舒适感的“痼疾”之一 ,影响电梯运行振动的因素很多 ,其中一个因素就是隔振垫的设计。本文将以某大厦一部电梯为例… 相似文献
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《Mechanism and Machine Theory》1991,26(7):697-709
A method of determining polyhedrons of positioning accuracy of mechanical manipulators is developed. Practical significance of the method is illustrated by numerical examples. Polyhedrons of positioning accuracy for a manipulator of 6-R type are calculated for several positions. 相似文献
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依据JJG880-2006浊度计检定规程,介绍了浊度计示值误差测量结果不确定度的评定方法,对配制标准溶液所使用的玻璃量器所引入的不确定度分量进行了分析和评定。 相似文献
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A new method of decomposition of the interval of the values of random variables based on results of optimization of the nonparametric estimate of the probability density of the Rosenblatt-Parzen type is proposed. Its application in the problem of testing the hypothesis of identity of the distribution laws of two sequences of one-dimensional random variables is considered. 相似文献
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The article presents a brief review of the wear models based on the kinetic thermofluctuation approach. The materials were developed using SamGTU sclerometric programming software and a set of instruments developed at Samara Engineering University for assessing the parameters of kinetic thermoactivation for surface fracture deformed by friction. The first obtained results of assessments and the estimated prediction of wear resistance exemplified by tribocouple of the aircraft chassis are presented. 相似文献