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International Journal of

Recent Trends in Engineering

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International Journal of Recent Trends in Engineering (IJRTE)

ISSN 1797-9617

Volume 1, Number 5, May 2009

Issue on Mechanical Engineering

Page(s): 176-180

Synthesis of High Purity Micron Size Boron Carbide Powder from B2O3/C Precursor

J. A. Bigdeloo, and A. M. Hadian

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Among the refractory carbides, next to carbides of tungsten, titanium and silicon carbide, boron carbide (B4C) has of late assumed great significance as a strategic material because of its high hardness, low density, and high cross section for neutron absorption, chemical inertness, and etc. The main applications of this material include military industries, nuclear industries, solid fuels for rockets, coating resistant component, and etc. In this research, boron carbide has been produced by sol-gel method from inexpensive raw materials such as boric acid and citric acid in micron particle size. Aqueous solution of boric acid in presence of citric acid forms a stable gel under controlled pH condition (pH=2-3). The gel pyrolyzed at 600, 650, 700 and 750C temperatures under vacuum. From XRD patterns it was found that the ratio of B2O3 to C in the precursor powder pyrolysed at 650C was better compare to the other temperatures for production of composite precursor with carbon matrix and boron oxide as reinforcement. Those composite precursors heated under vacuum at 5C/min up to 1350, 1450 and 1500C and kept 2.5 hrs. Final product has been characterized by X-ray diffraction (XRD), particle size analysis (PSA), scanning electron microscopy (SEM) and chemical analyses. The purity of product for 1.6 and 1.9 ratios of raw materials is 86.14% and 91.26% (weight percent), respectively. By using this method boron carbide powder with D90 equal to 3.43 micron can be produced.

Index Terms

boron carbide, boric acid, citric acid, powder synthesis, sol_gel

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