Synthesis of silicone carbide nanowhiskers by microwave irradiation method
This work described the synthesis of silicon carbide nanowhiskers (SiCNWs) by using the microwave heating.. The main objective of this project is to study the feasibility of synthesis of SiCNWs from expanded graphite (EG) and silica using microwaves heating. Several parameters were studied such a...
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| Format: | Thesis |
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| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/76729/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/76729/2/Full%20text.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/76729/3/Declaration%20Form.pdf |
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| Summary: | This work described the synthesis of silicon carbide nanowhiskers (SiCNWs) by using
the microwave heating.. The main objective of this project is to study the feasibility of
synthesis of SiCNWs from expanded graphite (EG) and silica using microwaves
heating. Several parameters were studied such as the effect of ratio of graphite and
silica, heating temperature, heating duration and types of graphite on the formation of
SiCNWs in term of morphology, compositions, optical properties and purity. In this
study, SiCNWs was synthesized by microwave heating mixture of EG and silica and the
effect of processing parameters on the synthesis were studied. For effect of ratio of EG
and silica, the mixture of EG and silica with the ratio 1:3 was found to be suitable for
the synthesis of SiCNWs because the formation of high purity β-SiC nanowhiskers.
Mixture of silica and EG with the ratios 1:5 and 1:7 had the traces of unreacted graphite.
Study of effect of heating temperature revealed a temperature at 1400 ºC is suitable for
the synthesis of SiCNWs. β-SiC appeared as the only phase in the XRD pattern of
SiCNWs formed at 1400˚C. FESEM imaging confirmed the presence of only a
negligible amount of graphite or silica in SiCNWs synthesized at 1400˚C. Meanwhile,
PL spectrum indicated the presence of single phase β-SiC peak at 440 nm which is
associated with band gap of 2.8 eV. Single absorption bands of Si-C bond were detected
at 803.5 cm-1 in FTIR analysis. SiCNWs produced in this study at 1400˚C has good
thermal stability with 6% of weight loss. Effect of heating duration was also studied and
40 minutes was found to be the most ideal heating duration for the synthesis of
SiCNWs. β-SiC appeared as the only phase in the XRD pattern for SiCNWs formed by
using 40 and 60 minutes of heating duration with no traces of unreacted silica and
graphite. FESEM imaging confirmed that no trace of graphite or silica was present in
SiCNWs synthesized at heating duration of 40 and 60 minutes. SiCNWs produced by
heating at 40 and 60 minutes have high thermal stability with weight loss lower than
6%. It was found that SiC nanowhiskers (SiCNWs) were formed when EG was used as
the starting material, while SiC nanoparticles (SiCNPs) were formed when FG was
used. β-SiC appeared as the only phase in the x-ray diffraction pattern for SiCNMs
formed by FG and EG. FESEM confirmed that no trace of graphite or silica was present
in both SiCNWs and SiCNPs. Meanwhile, photoluminescence spectra show the
presence of β-SiC peak at 440 nm and associated with band gap of 2.8 eV for both
SiCNWs and SiCNPs. Absorption bands of Si-C bond were detected at 803.4 cm-1 for
SiCNPs and 802.5 cm-1 for SiCNWs in the FTIR spectra. SiCNWs and SiCNPs have
high thermal stability with weight loss less than 6 %. In conclusion, SiCNWs and
SiCNPs have been successfully synthesized through the microwave heating of a mixture
of silica/EG and silica/FG in an argon atmosphere. |
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