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Heterogeneousnucleation Coating Technique of Graphite and Its Application

Author: ZouLingLi
Tutor: WuZuoZuo
School: Wuhan University of Science and Technology
Course: Inorganic non-metallic materials
Keywords: Graphite Heterogeneous Nucleation coated Surface Modification MgO-C castable
CLC: TQ02
Type: Master's thesis
Year: 2002
Downloads: 288
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Abstract

This paper mainly studied by heterogeneous nucleation of graphite surface modification. And on this basis, after the by Heterogeneous Nucleation law modified graphite introduced into MgO-C Castables modified graphite castable. By heterogeneous nucleation method is more successful applications in the nano-powder surface coating a surface modification method, this paper were used by heterogeneous nucleation method two different processes on the graphite surface processing, namely hydrolysis coating process and precipitation of the coating process. The the hydrolyzable coating process modification results show that: the pH value of the treatment temperature, the concentration of the cladding layer precursor solution, the buffer solution was added in an amount and cladding precursor added in an amount of several factors cladding layer formed on the surface of graphite have important influence. The optimum conditions for hydrolysis graphite surface modification pH = 6.5, the overlying layer precursor solution concentration = 0.064 mol ╱ l, T = 343K, V ₍ (buffer solution) = 40ml. Under this condition, the graphite surface is evenly coated with a layer of Al (OH) ₃ cladding layer of particles, the particle size of the cladding layer so that the graphite surface in the tens of nanometers to hundreds of nanometers. Further, the increase in the amount added with the modified processing systems cladding precursor, the particle diameter of the modified graphite surface coating increases, more densely distributed after modified by the hydrolysis method, the surface electrical properties of the graphite is changed, and its The isoelectric point was changed from 2 to 3 to 8 to 9, and close to the isoelectric point of the Al (OH) ₃ of; compared with unmodified graphite, modified graphite, and the contact angle of water is decreased by approximately 10 °. Al (OH) ₃ / graphite (wt%) = 10 when the hydrolysis method modified graphite oxidation weight loss rate than non-modified graphite decreased by approximately 20%, Thus, hydrolysis after modification, graphite and water wettability improvement, antioxidant improved precipitate modified coating process results indicates that: the selectivity of the precipitation pH value is smaller, the choice of pH in this test range of values, the graphite surface is not coated, only a small part of the surface of the local enrichment of flocculent cladding material deposited coating uniformity and increasing amount of precursors with cladding precipitation method modified graphite increased surface flocculent local enrichment of the cladding material, cladding thickening after precipitation method modified graphite surface electrical changes, its isoelectric point from 2-3 to 7-8, but The contact angle measurement results show that, after modified by the precipitation method, the graphite and the contact angle of water and did not change with the Al (OH) ₃ of the isoelectric point (8-9) there are some differences; , i.e. the modified graphite with water wettability no significant improvement; When Al (OH) ₃ / Graphite (wt%) = 10, the oxidation weight loss rate of the modified graphite than unmodified graphite decreased by approximately 10%, modified by the precipitation method, the oxidation resistance of graphite has been some improvement. water solution modified graphite and modified graphite preparation precipitated MgO-C castable, its liquidity and other The basic performance study results show that: castable MgO-C containing unmodified graphite compared to the aqueous solution of modified graphite MgO-C castable mobility and other basic performance slightly improved, and with the cladding precursors were added to the increase in the amount of aqueous solution of modified graphite MgO-C castable improved with the increasing amount of modified graphite, the aqueous solution modified graphite of the MgO-C castable performance was a significant downward trend MgO-C castable precipitation method modified graphite as the carbon source is not significantly improved.

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