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就怎么用透射显微镜分析聚合物表面涂层
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Materials from different manufacturers have been supplied to you. You are told that these are polymer coatings with embedded nanoparticles. Transmission electron microscopy (TEM) has been requested to assess if these nanometre sized particles differ depending on the manufacturer and if the distribution or size of particles varies through the thickness of the material. (a) Briefly outline what investigations you could undertake before using the TEM to explore any assumptions made? Outline any information you might expect to acquire with your chosen technique (s). (b) Outline the capabilities and main benefits of the TEM to this materials investigation. Indicate what types of information can be obtained. Your system has a scanning attachment. Identify suitable techniques and the detectors required that might be helpful (and what advantage they would have to this investigation) in a scanning transmission electron microscope). (c) What specimen thickness would be suitable for the TEM? Outline a possible preparation route for your materials and explain clearly what areas of your specimens you would examine. (d) What differences would there be in the quality of information gathered to using the same materials prepared for a scanning electron microscope 发自小木虫IOS客户端 |
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Thermal Barrier Coatings (TBCs) can be deposited using the EB-PVD process. Explain the manufacture of an EB-PVD TBC system a) First, select your chosen bondcoat system and describe in brief its manufacture. Justify your choice of system and the benefits you expect. b) Describe the EB-PVD deposition process and explain what modifications are required to the basic evaporation process to ensure correct stoichiometry, microstructure, adhesion and performance in service. Justify your choices by reference to the structural zone models of Movchen and Demenshichin, which was later updated to include pressure effects by Thornton. c) How does this microstructure modify thermal barrier coating performance? Discuss thermal conductivity, strain tolerance (compliance) and erosion resistance. 发自小木虫IOS客户端 |
5楼2016-02-03 21:53:50
2楼2016-02-03 09:38:18
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3楼2016-02-03 09:51:08
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首先说个前提,一般使用投射电镜的目的是为了观察尺度在0.2μm到0.2nm之间的亚显微结构. 这题目里说的是纳米颗粒,那么 1.在进行电镜观察的之前或者说同时,通常用XRD或定量分析材料的相组成情况(成分种类比例),用化学成分分析其元素组成情况. 2.透射电镜的主要优点在于分辨率高,对样品损伤小,通常用于对薄厚度样品的观察. 透射电镜的工作原理是:由电子枪发射出的电子束在真空通道中穿越聚光镜,聚成一束尖细、明亮而均匀的光斑,照射样品上.透过样品后的电子束携带有样品内部的结构信息,样品内致密处透过的电子量少,稀疏处多;经过物镜的会聚调焦和初级放大后,电子束进入下级的中间透镜和第1、第2投影镜进行综合放大成像,最终被放大了的电子影像投射在观察室内的荧光屏板上,最终转化为可见光影像. 题目里说的detector我没明白是什么意思 . 3.超薄样品,一般都是几百微米.制样的大致流程是切片→砂纸打磨→上胶除胶→离子减薄. 观察的区域的话… 我只用过SEM,TEM不太清楚 .SEM我一般是在开了电镜以后才知道 . 发自小木虫IOS客户端 |
4楼2016-02-03 11:10:05
