Microscopy polished samples

The properties and performance of cemented carbide tools depend not only on the type and amount of carbide but also on carbide grain size and the amount of binder metal. Information on porosity, grain size and distribution of WC, solid solution cubic carbides, and the metallic binder phase is obtained from metallographically polished samples. Optical microscopy and scanning and transmission electron microscopy are employed for microstructural evaluation. Typical microstructures of cemented carbides are shown in Figure 3. 

Scanning Electron Microscopy (SEM). Samples intended for SEM analysis normally were mounted directly on polished aluminum microscope stubs before irradiation. Several filaments were peeled before mounting to expose the sample interior to UV irradiation as described previously (8). The mounted filament samples were gold coated before examination to minimize charging in the electron beam. A Cambridge S-2 scanning microscope was used for all studies. 

STM Sanning Tunneling Microscopy Polished or cleaved surface (conducfing) Tunneling current contn sample and very sharp 1 1-5 nm 2-10 nm Atomic-scale reliel map ol surlace resolution vert. 0.002 nm, hor. 0.2 nm 39... 

The aim of this chapter is to illustrate the use of electron microscopy for the study of cementitious materials. Although imaging of fracture surfaces with SEs is perhaps the most commonly used technique, it is of limited use after the first day or so. The most useful technique is the study of polished sections by BSEs and characteristic X-rays. We have tried to illustrate some of the diverse applications of these methods, including the possibilities to obtain quantitative information by image analysis. However, the essential prerequisite is a well-polished sample, which is not easy to achieve. 

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]. 

Work concentrated on gangue quartz in main gold-bearing sulfides veins, and in late stage intrusion-related ( ) base-metal veins. Polished sections were first investigated by transmitted and reflected light microscopy to find suitable samples... 

Fig. 13.20. Optical heterodyne force microscopy (OHFM) and its application to a copper strip of width 500 nm, thickness 350 nm, on a silicon substrate, with subsequent chemical vapour deposition (CVD) of a silicon oxide layer followed by polishing and evaporation of a chromium layer of uniform thickness 100 nm and flatness better than 10 nm (a) amplitude (b) phase 2.5 [im x 2.5 m. Ultrasonic vibration at fi = 4.190 MHz was applied to the cantilever light of wavelength 830 nm was chopped at fo = 4.193 MHz and focused through the tip to a spot of diameter 2 im with incident mean power 0.5 mW the cantilever resonant frequency was 38 kHz. The non-linear tip-sample interaction generates vibrations of the cantilever at the difference frequency f2 — f = 3 kHz (Tomoda et al. 2003).

Optical microscopy is often the first step in surface analysis, since it is fast and easy to perform. It can be an aid in selecting the area of interest on a sample for further analysis with more complex methods. The application of classical optical microscopy to surface science is, however, limited because the maximum lateral resolution is in the order of the optical wavelength ( 500 nm). For opaque solids, the light penetrates into the material, giving optical microscopy a poor surface sensitivity. In addition, the depth of field is limited which calls for flat, polished surfaces or allows only plane sections of the sample to be viewed. 

In summary, sample preparation is an essential part of microscopy and there are many techniques (and variations) that can be used. The approaches very commonly used to prepare specimens for analysis are as follows The sample needs to be cut to size using one of the slicing methods outlined. The cut sample is either set in a mold or mounted externally on a polishing mount. This step is followed by a series of coarser to finer grinding on SiC grit... 

---