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ndltd-OhioLink-oai-etd.ohiolink.edu-osu1311955861
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu13119558612021-08-03T06:03:32Z Coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating Bhallamudi, Vidya Praveen <p>Flexible and electrically insulating alumina coatings, on metallic lead wires for high temperature applications, have been made using Electrophoretic Deposition (EPD) and Slurry coating techniques.</p><p>Experiments were done to study the effect of deposition current, solids content and alumina particle size on the EPD of alumina from aqueous suspensions. The alumina was dispersed using an ammonium salt of polyacrylic acid. A current of 1mA, solids content of 40 wt.%, 0.23 μm alumina particle size gave the best results for aqueous EPD. A pH of 8.17 and conductivity of 16280 X10<sup>-6</sup>(Ω.cm)<sup>-1</sup> gave the highest rate of deposition. However the overall effect of the pH and conductivity is not completely understood. The effect of sintering temperature, coating thickness, wire thickness, wire material and its surface condition on adherence of the coating were also studied. The various parameters were qualitatively observed by studying the variation of "crack density" due to these parameters. Adherence was observed to be better for thinner coatings and for coatings made on thinner wires. Adherence also increased with sintering temperature. Heat treatments were done in air and vacuum to modify the surface condition. The heat treatments increased the surface roughness of the wires, which increased the crack density. Platinum showed the least effect due to the heat treatments, while chromel-p showed the maximum. Aqueous EPD samples showed and pores. Non-aqueous EPD was also studied. Coatings were made from suspensions in mixture of ethanol and acetone. They did not have any drying cracks and showed only transverse cracks on sintering. The rate of coating is also much higher than in the case of aqueous EPD.</p><p> In the case of slurry coating, a machine was successfully built to continuously slurry coat metal wires. A slurry based on MEK and toluene, as dispersing liquids, and Butvar B-79 binder was used. An optimal slurry composition and rate of drawing were determined.</p><p> The resistivity of the coatings, made by both EPD and slurry coating was found to be of the order of 10<sup>8</sup> ohm-cm, even at 1050°C.</p> 2000 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1311955861 http://rave.ohiolink.edu/etdc/view?acc_num=osu1311955861 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
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NDLTD
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| language |
English
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NDLTD
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| author |
Bhallamudi, Vidya Praveen
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| spellingShingle |
Bhallamudi, Vidya Praveen
Coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating
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| author_facet |
Bhallamudi, Vidya Praveen
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| author_sort |
Bhallamudi, Vidya Praveen
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| title |
Coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating
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| title_short |
Coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating
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| title_full |
Coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating
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| title_fullStr |
Coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating
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| title_full_unstemmed |
Coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating
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| title_sort |
coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating
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| publisher |
The Ohio State University / OhioLINK
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| publishDate |
2000
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| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1311955861
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| work_keys_str_mv |
AT bhallamudividyapraveen coatinghightemperatureleadwireswithelectricallyinsulatingaluminabyelectrophoreticdepositionandslurrycoating
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| _version_ |
1719430134495182848
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