Various different applications of indium Ohyphen;ring seals are briefly reviewed. A critical factor in the construction of any indium pressurehyphen;type seal is the finish of the surface cold welding to the indium. We present the results of some tests on surface finishes achieved by machining and grinding, which indicate certain conditions which ensure the integrity of the seal. Specifically, we find that if the metal surface has to be ground, it should be ground, and then polished to a surface granularity of less than 5 thinsp;mgr;. This condition can be obtained using a grinding powder with a mesh size of 3200 or greater. Alternatively, careful surface preparation using a lathe furnishes an equally satisfactory finish, providednoattempt is made to lsquo;lsquo;improversquo;rsquo; the surface using emery paper, etc. In the latter case, the fine helical pattern imparted by the lathe is essential for the fabrication of a reliable seal.
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