Sawing, Grinding, and Polishing

The wide variety of available sawing, grinding, and polishing equipment, and the necessity for economically producing a high quality polished section, result in several options in building a compact, relatively maintenance free and inexpensive system for sample preparation. 

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Equipment needed for microscopy in a cement plant may range from only a polarized-light microscope required for powder mount analysis to sawing, grinding, and polishing equipment necessary for thin-sec-tion and polished-section study. Two somewhat idealized lists of equipment are given in Table 11-1. The "Economy" column in the table contains only the minimum equipment for powder-mount study and polished-section examination. The other column also contains items for preparation of thin sections. 

In fact, diamonds are not only beautiful to look at, but they are also very useful. Because they are so hard, they can be used to saw, drill, grind, and polish. So, we use diamond saws to cut microchips for computers. We use diamond... 

Resin-bonded diamond discs placed on a flat table-top function quite well for rapid hand grinding of a saw-cut surface of epoxy-encapsulated clinkers preparatory to polishing (Hoodmaker, personal communication, 1985). Afew drops of propylene glycol are used as the grinding and polishing liquid. The diamond discs are cleaned with soap and water. 

Cylinders one inch in diameter were made using Epotek two-part epoxy, and up to 18 holes 2mm in diameter and 3mm in depth were drilled in the flat surface of the hardened disk. Fresh epoxy and obsidian samples, cut earlier with a fast-speed diamond saw if necessary, were inserted in the holes and allowed to harden for 48 hours before grinding and polishing to a 1-micron finish. Sample disks were carbon-coated prior to analysis to minimize local surface charging under the electron beam. 

It is possible to affect electrochemical grinding and polishing by using a cathodic wheel with an anodic workpiece separated by a flowing electrolyte. Tungsten carbide tools are usually prepared by such a process. An electrochemical saw has also been produced. 

Standard metallographic methods [7, 82] are used for grinding and polishing. Large samples are precut with a saw to fit into 1 to 2 inch diam-... 

Industrial-grade diamonds are used for a host of applications that exploit diamond s extreme hardness, wear resistance, and low coefficient of friction. These include diamond-tipped drill bits and saws, dies for wire drawing, and as abrasives used in cutting, grinding, and polishing equipment (Section 13.6). 

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