Effect of pH on the dispersability of silicon carbide powders in aqueous media

Rao, R Ramachandra and Roopa, HN and Kannan, TS (1999) Effect of pH on the dispersability of silicon carbide powders in aqueous media. Ceramics International, 25 (3). pp. 223-230.

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The dispersion behaviour of commercial silicon carbide (SiC) powders of various grit sizes in deionised water was studied over the pH range 2-11. The slips were characterised for the state of their dispersion by employing the various quantitative diagnostic techniques e.g. particle size distribution,sedimentation, rheological behaviour, viscosity and zeta potential. SiC powders were found to get optimally dispersed at a pH value of 10 at which their near newtonian slips displayed a minimum in sedimentation height and viscosity and a maximum in zeta potential. In the acidic (pH =2-7) range the slips were highly flocculated as manifested by larger sedimentation height, higher viscosity, lower zeta potential value and thixotropic, non-newtonian flow behaviour. Moderate to good dispersion conditions were observed in the alkaline range of pH =7-10. The above results corroborate well with the casting behaviour of these slips. The density and moisture content as well as the green microstructure of the cast product bear a direct relationship to the state of aggregation of the slips induced by the alterations in the pH of the slurry.

Item Type: Article
Additional Information: Copyright belongs to Elsevier Science Ltd.
Uncontrolled Keywords: A.Slip casting;D.Silicon carbide;Aqueous dispersion;Slip characterisation;Viscosity;Zeta potential;Sedimentation
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Depositing User: Mr. N A
Date Deposited: 08 Jun 2006
Last Modified: 03 May 2012 06:14
URI: http://nal-ir.nal.res.in/id/eprint/1459

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