Grinder for Sectioning Solid Diffusion Specimens

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Abstract
A grinder which can be used for sectioning diffusion specimens in which the average diffusion distance is a very few microns is described. Three fixed steel balls are used to determine the grinding plane of the instrument, and the specimen is held with constant orientation at the center of the triangle formed by the balls. The orientation of the grinding plane with respect to the specimen surface can be changed to make the two parallel by adjusting the lengths of the legs to which the steel balls are attached. These lengths can be adjusted over several centimeters, permitting a large variation in specimen thickness and orientation. A differential screw arrangement on each leg makes it possible to orient the grinding plane and crystal surface to within 5×10−6 radian with respect to one another. The shaft on which the specimen remains mounted during the entire grinding procedure can be moved in a line perpendicular to the grinding plane so that the specimen surface protrudes beyond the grinding plane. A solid grinding plate is then used to grind the specimen away until the surface lies in the plane. Since no loose grinding compound is used, the material removed from the specimen can easily be collected for preparing a radioactive slide. It is also possible to assay the radioactivity of the specimen itself. The motion of the shaft, and, consequently, the thickness ground away, is measured directly using an electronic indicator and is checked every 10 μ against gauge blocks. It is estimated that sections parallel to within 10−5 radian and with the thickness known to the order of a few hundredths of a micron can be removed with the device, the lower limit on the thickness of the slice being about 1 μ.
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