共查询到20条相似文献,搜索用时 109 毫秒
1.
2.
采用乙二胺四乙酸(EDTA)分子自组装技术在硅基材料表面制备了稀土La复合纳米膜,利用浓缩体系全功能稳定性分析仪研究了自组装改性剂制备温度对氢氧化镧胶粒稳定性的影响,通过X-射线荧光光谱仪(XRF)研究了自组装改性剂溶液pH值对复合纳米膜中引入La量的影响,利用AFM研究了EDTA/La摩尔比及组装时间对复合纳米膜形貌的影响,利用AFM研究了在硅基材料表面自组装复合稀土纳米润滑膜前后的摩擦磨损性能.结果表明,在玻璃基片表面成功地组装上了稀土La纳米薄膜;相对于原构件,La纳米膜表面粘附力较小,摩擦因数亦较低,呈现出良好的润滑效果;其摩擦稳定性和耐磨性都有很大程度上的提高. 相似文献
3.
4.
5.
6.
7.
8.
为解决微硅粉增密仓料位无法监测而引起输料管道堵塞的问题,针对微硅粉这一特殊介质完成了微硅粉增密仓料位在线实时监测装置的系统设计.在描述系统工作原理的基础上,完成了传感器的电路连接和系统电源设计,系统采用STC系列单片机作为控制核心,完成了单片机的外围硬件电路设计.同时通过单片机编程实现了模拟量到数字量的转换并控制料位信号通过数码管输出显示.从软硬件两个方面阐述了系统的设计过程,最终开发出一种成本低、精度高的微硅粉增密仓料位实时监测装置. 相似文献
9.
对内部无缺陷的单晶硅纳米级磨削过程进行了分子动力学仿真,从磨削过程中瞬间原子位置、磨削力、原子间势能、损伤层深度等角度研究了纳米级磨削加工过程,解释了微观材料去除、表面形成和亚表面损伤机理。研究表明:磨削过程中,单晶硅亚表面损伤的主要形式是非晶结构形式,无明显的位错产生,硅原子间势能的变化是导致单晶硅亚表面损伤的重要原因;另外,发现磨粒原子与硅原子之间有黏附现象发生,这是由于纳米尺度磨粒的表面效应而产生的。提出了原子量级条件下单晶硅亚表面损伤层的概念,并定义其深度为沿磨削深度方向原子发生不规则排列的原子层的最大厚度。 相似文献
10.
通过分析软质层的形成、作用以及纳米磨料的自身变形对材料去除的影响,改进了CMP过程的接触力学模型;分析了纳米磨料自身变形量对磨料嵌入硅晶片基体材料的深度的影响,以及纳米磨料硬度对抛光表面粗糙度的影响。结果表明:软质层的存在增加了单个纳米磨料所去除材料的体积,且对基体材料有保护作用,减小了纳米磨料嵌入基体材料的深度;纳米磨料的自身变形抵消了纳米磨料嵌入基体材料的切削深度,从而也决定了抛光表面的粗糙度;纳米磨料的自身变形量与纳米磨料的硬度有关,硬度低的纳米磨料自身变形量大,因而切削深度小,抛光后表面的粗糙度值低。 相似文献
11.
12.
13.
Solid particle erosion tests were conducted on four different types of silicon carbide ceramic composites. The composites are cotton fabric based Si/SiC with and without chemical vapour infiltration, fine teak wood powder based Si/SiC and coarse teak wood powder based Si/SiC. The erodents used are angular SiC particles of average size 80, 250 and 450 μm. The velocities with which particles impacted on the target materials were varied from 20 to 50 m/s. Similarly the angle of impact was varied from 20° to 90°. Scanning electron microscopic observations on the eroded surface show brittle and cleavage like fracture. Fine teak wood powder based Si/SiC ceramic shows better erosion resistance than the other ceramics. Homogenous distribution of SiC grains with the presence of very fine grains of silicon and carbon is responsible for the improved erosion resistance. The higher erosion rate in cotton fabric based SiC arises from its microstructure. Here, the free carbon and free silicon grains are large in size and the SiC phase has very low hardness as compared to the erodent. 相似文献
14.
QIN Xunpeng HUA Lin School of Materials Science Engineering Wuhan University of Technology Wuhan China 《机械工程学报(英文版)》2007,20(4):12-14
Plastic deformation is an important process to improve properties and obtain final products made of sintered powder materials.Sintered ferrous material is widely used in many engineering departments and its deformation characteristics are typical for most sintered powder materials.Factors such as deformation strengthening,instantaneous and initial relative densities,ete,on the subsequent yield strength are studied,and an approach to determine the plastic stress coefficient and hardening exponent is derived,which is based on the yield criterion and the strengthening laws of plastic deformation of sintered powder materials as well as on a uni-axial compression experiment of a sintered ferrous cylinder specimen.A unified form of the yield criterion function is obtained,in which the initial and the subsequent yields of sintered powder materials are expressed. 相似文献
15.
The properties of ceramic materials (high hardness, high-temperature capability, low coefficient of thermal expansion) are of interest to rolling element materials. One of the most interesting materials is silicon nitride.The paper presents an experimental study of the influence of oil additives (Cl, S, P, cerium dioxide (CeO2)) on spread cracks in silicon nitride. The additives Cl, S, P are bound in molecules in liquid form soluble in the base oil. The CeO2 is purely in powder form in suspension. The use of CeO2 powder was made based on the good results of polishing of silicon nitride. A ceramic angular contact ball bearing was modelled using a four-ball machine. Silicon nitride, -in diameters balls were artificially damaged with pre-cracks. Ring formed pre-cracks were propagated on the ball surface by a blunt impact load using a tungsten carbide ball under five various impacts.Rolling contact fatigue failure modes were studied under high contact stresses and speed. The surface of silicon nitride balls before and after failure was examined using scanning electron microscopy.The research of the present paper shows that fatigue failure under rolling contact loading is markedly sensitive on the size of pre-cracks and oil additives. Propagations of surface pre-cracks takes place under fatigue load. Primary and secondary surface crack propagation are described. 相似文献
16.
Rusnaldy Tae Jo Ko Hee Sool Kim 《The International Journal of Advanced Manufacturing Technology》2008,39(1-2):85-91
Micro-end-milling can potentially create desired 3D free-form surface features on silicon using ductile machining technology. A number of technological barriers must be overcome for micro-end-milling to be applied in the cutting of single crystal silicon. To produce smooth surfaces on brittle materials, such as silicon, it is important that the material be machined in the ductile mode. A major limitation of machining brittle materials is that the process of removing the material can generate subsurface damage. We have carried out an experimental study to find the optimum cutting conditions for obtaining ductile regime machining using a micromilling machine. The ductile and brittle regimes in the machining of silicon using diamond-coated end mills were demonstrated by machining grooves. The force ratio, Ft/Fc, was used to determine the milling performance on silicon. The experimental data show that the dominant ductile cutting mode was achieved when Ft/Fc?>?1.0. 相似文献
17.
线切割机对硅片切割能力的强弱,与砂浆的粘度有着不可分割的关系。而砂浆的粘度又取决于硅片切割液的粘度、硅片切割液与碳化硅微粉的适配性、硅片切割液与碳化硅微粉的配比比例、砂浆密度等。只有达到机器要求标准的砂浆粘度,才能在切割过程中提高切割效率和成品率。 相似文献
18.
研制的微波连接装置由微波源,单模谐振腔,红外光纤测温仪,焊件加压机构和真空及抽气系统组成。并在此装置上用不同中间层材料对氮化硅陶瓷进行了微波连接。 相似文献
19.
Paulo Peças Elsa Henriques 《The International Journal of Advanced Manufacturing Technology》2008,37(11-12):1120-1132
The addition of powder particles to the electrical discharge machining (EDM) dielectric fluid modifies some process variables and creates the conditions to achieve a higher surface quality in large machined areas. This paper presents a new research work that aims to study the improvement in the polishing performance of conventional EDM when used with a powder-mixed-dielectric (PMD-EDM). The analysis was carried out varying the silicon powder concentration and the flushing flow rate over a set of different processing areas and the effects in the final surface were evaluated. The evaluation was done by surface morphologic analysis and measured through some quality surface indicators. The results show the positive influence of the silicon powder in the reduction of crater dimensions, white-layer thickness and surface roughness. Moreover, it was demonstrated that an accurate control of the powder concentration and flushing flow is a requirement for achieving an improvement in the process polishing capability. 相似文献
20.
粉末球磨预处理对高硅铝合金材料组织与物理性能的影响 总被引:2,自引:0,他引:2
为制备出能满足使用要求的高硅铝合金电子封装材料,采用高能球磨对Al-Si合金粉末进行氧化预处理,结合包套热挤压制备Al2O3与SiO2增强的弥散强化型铝硅复合材料,并采用透射电镜、金相显微镜及热物性测试仪,对材料显微组织、密度、气密性、热膨胀系数及热导率进行分析测试.试验结果表明:与高温空气氧化相比,粉末高能球磨后,所制备材料的晶粒更加细小,特别是硅粒子已明显细化;粉末球磨后所制备材料密度接近于理论密度,其致密度在99%左右;材料气密性很好,在1 nPa·m3·s-1以下;材料热膨胀系数随粉末球磨时间延长而下降,当球磨时间超过24 h后,材料膨胀系数小于13 (K-1;随着球磨时间延长材料热导率增加,球磨32 h后,材料热导率高达145.5 W·m-1·K-1. 相似文献