Abstract
Biomass husk is a cost effective source to produce silicon based ceramics. Present work deals with the catalytic synthesis of silicon carbide from biomass husk of indigenous rice as raw materials. Rice husk samples were treated with different concentrations of sodium silicate, 40% hydrochloric acid and a mixture of 40% HCl and 2 gl-1 Na2SiO3. Treated husk were pyrolysed at 1350°C in argon atmosphere and then oxidised to eliminate unreacted carbon. Products were characterised by XRD, SEM and EDS techniques in order to confirm the carbide formation, to identify carbide morphology and to conduct elemental analysis respectively.Maximum yield was obtained in case of catalytic treatment with 2 gl-1 Na2SiO3. Acid treatment, although showed no considerable increase in yield, fostered whiskers formation instead of particles.
Highlights
Silicon carbide offers a wide spectrum of electrical, chemical and mechanical properties, for which it is used in a variety of modern applications [1]
High purity silicon carbide can be synthesised from rice husk (RH) which generally contains 71 – 87 wt% organic components such as cellulose, lignin and sugar [3], and 13-29 wt% inorganic components
Oxidation of RH vaporizes the organic part and residual inorganic component is termed as rice husk ash (RHA) [4,5] more than 95% of which comprises ultrafine silica [6]
Summary
Silicon carbide offers a wide spectrum of electrical, chemical and mechanical properties, for which it is used in a variety of modern applications [1]. The amorphous silica in the RH can produce silicon carbide, silicon nitride, silicon oxynitride, pure silicon and other silicon based compounds depending upon the composition, atmosphere, reaction temperature and pre-pyrolysis treatment. Pyrolysis of HCl treated RH led to improved yield of SiC as compared that obtained from untreated raw RH [10]. Ground and dried RHwere subjected to different processes including direct pyrolysis, oxidation of pyrolysed powder to remove residual carbon and HF treatment to remove SiO2 and get pure SiC powder. Pre-treated samples were pyrolysed one by one in SentroTech (STT-1650) tube furnace that was heated from ambient to 1350°C at a constant rate of 5°Cmin–1, soaked at maximum temperature for 30 min. Energy dispersive spectrometry (EDS) coupled with SEM provided elemental analysis of the products
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