Now showing 1 - 3 of 3
  • Publication
    Dielectric properties and microwave absorbing properties of silicon carbide nanoparticles and silicon carbide nanowhiskers
    Silicon carbide (SiC) is well known for their outstanding microwave absorbing properties. SiC nanomaterials (SiCNMs) are expected to have better microwave absorption performance due to their high specific surface area. To date, no study was reported to compare the dielectric properties and microwave absorbing properties of different type of SiCNMs. Therefore, the objective of this paper is to compare the dielectric properties and microwave absorption properties of different types of SiCNMs. In this paper, SiC nanoparticles (SiCNPs) and SiC nanowhiskers (SiCNWs) were characterised using SEM and XRD. In addition, their dielectric properties and microwave absorbing properties were measured using network analyser and transmission line theory. It was found that SiCNWs achieved higher dielectric constant and loss factor which are and εr’ =17.94 and εr″ = 2.64 compared to SiCNPs that only achieved εr’ = 2.83 and εr″ = 0.71. For microwave absorbing properties, SiCNWs and SiCNPs attained minimum reflection loss of -10.41 dB and -6.83 dB at 5.68 GHz and 17.68 GHz, respectively. The minimum reflection loss of SiCNPs and SiCNWs obtained in this study is much lower than the nanometer-SiC reported previously. These results suggested that SiCNWs can be an ideal candidate of microwave susceptors for various microwave applications
      1  13
  • Publication
    Nanoparticle synthetic methods: Strength and limitations
    ( 2020-01-01)
    Ramanathan S.
    ;
    ; ;
    Poopalan P.
    ;
    Perumal V.
    Nanoparticles (NPs) are produced through nanotechnology development by reducing the metal to its nuclear size. NP synthesis includes a few techniques, such as physical, chemical, and biological techniques. Physical methods avoid NP solvent contamination but it is not negligible to consume a large quantity of energy for condensation and evaporation of particles. In addition, extremely high modulation of temperature and pressure indirectly expends the cost of NPs synthesis. In the chemical technique, reducing agents and protective agents are used to synthesize NP and prevent agglomeration in order to synthesize high purity and stable NP. High intake of strong chemicals leads to contamination of the synthetic NP. In comparison to NP’s synthesis by chemical and physical techniques, the interest in NP biological synthesis has concentrated on its ecofriendly and effective technique. The biological technique used under green synthesis differs with the type of reduction agent used as microorganisms (bacteria and fungi) and plants and their extracts. Exclusion in the consumption of powerful chemical agents and set-up of high-energy reactions highlights the significant benefits of biological technique in NP synthesis. Thus, the synthesis of NP with plant extracts by biological method is the appealing technique for a large-scale production of NP and has a higher potential in significant medicinal applications.
      2  23
  • Publication
    The effect of graphite type on the synthesis of SiC nanomaterials by microwave-assisted synthesis
    SiC nanomaterial (SiCNM) is known for its excellent properties and has great potential for a wide range of applications. In this article, preparation of SiCNMs from different types of graphite was performed by microwave-assisted synthesis. Different types of graphite which are graphite flake (GF) and expanded graphite (EG) were used to react with silica for the synthesis of SiCNMs in laboratory microwave furnace at 1400 Â°C. It was found that SiC nanowhiskers (SiCNWs) were formed when EG was used, while irregular shaped SiC nanoparticles (SiCNPs) were formed when GF was used. β-SiC appeared as the only phase in the XRD patterns for both SiCNMs formed using GF and EG. SiCNWs and SiCNPs have interplanar spacing of around 0.25 nm which is the axial direction of [111]. The difference of formation mechanism is believed to be the origin of different morphology of SiCNMs synthesized from different types of graphite.
      3  25