Cross-section sample preparation

Grain size Cloth type Critieal thiekness Remarks 

6 pm diamond hard woven nylon eloth 20 pm 1 flattening 

25 pm diamond soft long-haired eloth 10 pm polish 

Put the ground sample stack into acetone until it detaches from the specimen holder. The stack is very brittle so it is impossible to pick it up with tweezers. Use a small piece of tissue paper soaked in acetone. The stack will stick to the soaked tissue paper and can thus be removed. The acetone on the tissue paper evaporates quickly and the stack then falls off by its own weight. Clean the sample carefully with a lens tissue wrapped around the tip of a pair of tweezers using acetone. Separate all strips of the cross-section carefully with a sharp knife. The glue is not so strong any more since the cross-section is less than 

Sometimes, one has to check a specific area within a micrometer-sized region, especially when one wants to check the microstructure of a device such as a 

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There have been a number of review articles on TEM sample preparation techniques [4.2-4.5]. TEM samples of high Tc superconductors are mostly prepared either by crushing, cleaving or ion milling. These methods will be dealt with in Sections 4.2 and 4.3. Minor details frequently determine the success of a technique. To illustrate this, we will describe the normal preparation procedure for both techniques while we will concentrate on some tricks to obtain a good TEM sample reliably and fast. The method described here will mainly be focused on cross-section sample preparation. Finally, two new techniques will be introduced, (i) a simple TEM cross-section ion shadow... 

Fig. 4.12. Schematic showing cross-section sample preparation by the metal cylinder method.

It is time consuming and precise work to prepare a TEM cross-section sample by the ion milling method as described above. One has to glue the sample, grind the sample down to about 10 pm and then ion mill the sample at a low angle, 15°, to obtain electron transparency. In order to control the final ion milling process, one often has to check whether the sample is ready or not. Here we introduce a new simple and useful preparation method for TEM cross-section sample preparation the so-called ion shadow method [4.27]. 

Fig. 4.15. Schematic showing ion shadow cross-section sample preparation method.

Finally, microscopic examination of samples often requires their preparation as cross sections or thin sections, or by mounting the sample on a glass slide by means of a mounting medium. For preparing thin and cross sections, samples are embedded in a polymer solution. After curing of the polymer, the thin or cross section is obtained by polishing the embedded sample with SiC abrasive disks. Aluminum suspensions or diamond paste are occasionally employed in a final polishing step. 

Sandies were collected from bottom ash, cyclone ash and hot filter dust in some of the CFB test runs carried out with straw. The samples were analysed by light microscopy and electron microscopy. With the first method, an overall inspection was carried out in order to monitor agglomerates and their form. Afterwards, cross-sections were prepared for the electron microscopic analysis (SEM), in which the CCSEM (computer controlled electron microscopy) technique was applied. These analyses were carried out at VTT Manufacturing Technology. In this analysis, sample particles were analysed for their size and chemical composition. 

From the ash samples, cross-sections were prepared and analysed by SEM. In the analysis, particle sizes and their chemical con osition were deteimined. In the analysis of chemical composition, the following elements were measured Si, Al, Fe, Ca, Mg, K, Na, Ti, P, S, Cl, (Mn), The summary results of this SEM analysis are shown in Figure 4. The con osition measured for particles was conpared with the chemical composition of ash of the feedstock straw (also indicated in Figure 4). According to the results, the most abundant substance in bottom ash was silicon, the amount of which was locally much higher than that of straw ash. The potassium content was quite equal from particle to particle. 

Energy-dispersive x-ray microanalysis was used to qualitatively verify the graded profile. A cross-sectioned sample, polished to a 1pm finish, was prepared. The measurement was conducted from the near-surface region to the center of the sample with step size of 50 pm using a JEOL 35C scanning electron microscope. The x-ray emission intensities for TiKot, AlKa, and ZrLot were collected at each point. 

Compared to the normal sample preparation method, this method takes much less time, and it is not necessary to check whether the sample is ready or not. By using this technique, one can obtain more or less the same quality cross-section samples as with the conventional method even for HREM studies. However, one can not tilt the sample so much. Fortunately, it is still suitable for an epitaxially grown thin film. 

Optical cross sections were prepared by cutting the samples so that they would fit in a 30 mm mount. Once placed into the mounts, Buehler Epomix was added, the samples cured, and then... 

Compared with transmission electron microscopy (TEM), it can provide three-dimensional images without expensive sample preparation and yield far more complete information than the TEM profiles available from cross-sectioning samples. 

Blom DA, Dunlap JR, Nolan TA, Allarda LF. Preparation of cross-sectional samples of proton exchange membrane fuel cells by ultramicrotomy for TEM. J Electrochem Soc 2003 150(4) A414-8. 

For each seal type, cross-sections were prepared through samples that had completed their target exposure periods and been removed from the test, or from the longest exposure samples that had been removed due to failure. 

Figure 14.6a shows the cross-section scanning electron microscopy (SEM) image of the electrolyte and hydrogen membrane. Before preparation of the cross-section sample, the tungsten protection layer was coated on the electrolyte layer to avoid damage. As seen, a solid and uniform electrolyte layer without... 

Determination of gold concentrations to ca 1 ppm in solution via atomic absorption spectrophotometry (62) has become an increasingly popular technique because it is available in most modem analytical laboratories and because it obviates extensive sample preparation. A more sensitive method for gold analysis is neutron activation, which permits accurate determination to levels < 1 ppb (63). The sensitivity arises from the high neutron-capture cross section (9.9 x 10 = 99 barns) of the only natural isotope, Au. The resulting isotope, Au, decays by P and y emission with a half-life of 2.7 d. 

Similar to prepared metallographic samples, the injection molded samples were cut along the flow direction, smoothed, and polished in order to expose their internal surface. After proper etching, the treated surfaces of the flank cross-section were photographed using a polarized light optical microscopy. Based on the color differences between the TLCP and matrix, volume fraction and aspect ratio of the TLCP fibers were measured [23]. 

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