Identifier: alloysoftungsten00hars (find matches)
Title: Alloys of tungsten by diffusion
Year: 1920 (1920s)
Authors: Harsch, John William
Subjects: Tungsten alloys Diffusion Theses
Publisher:
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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here by the use ofa Leeds and Northrup optical pyrometer. Graphite crucibles v/ere used and the alloy protectedby powdered carbon. (2) Grinding and Polishing Apparatus. The grinding was done on a machine carrying four gradesof emery wheels. After a specimen had been ground down on theemery wheels, it was polished successively on numbers 1, 0, 00,and 000 emery paper. The 0000 grade of emery paper has generallybeen found to scratch the specimen, and therefore it has not beenused. After polishing on 000 paper, specimens were further po-lished on broadcloth saturated with levigated alumina yf2. Thishas proved a v-ry quick and excellent method of polishing, es-pecially when the hardness encountered in these alloys is con-sidered. Rouge on broadcloth was used in the final polishingprocess. (3) Etching Reagents. Two etching reagents have been used: hydrofluoric acid,containing a few drops of nitric acid, and boiling hydrogen per-oxide. Only a very few seconds time are required in the case of
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14 the hydrofluoric acid, while, in the case of the hydrogen per-oxide, about thirty to sixty seconds are required. (4) Photographic Apparatus. All photomicrographs have been taken with a LeitzMetallograph (Fig. IV,), using a carton arc as the source of light.This instrument is well equipped with all sizes of objectives andeyepieces, including apochromatic objectives, correction eye-pieces, and micro suramars. (5) Material. The tungsten used in this work was procured from the Fansteel Products Company of North Chicago, Illinois. It was in the form of sintered bars.

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