Now showing 1 - 9 of 9
  • Publication
    Prediction of carbon concentration profile within carburised-carbon steel 1024 using Alternating Direction Implicit (ADI) method
    Pack carburisation is recognised to improve the carbon surface content of carburised-carbon steel 1024 that enhance the surface hardness and further can be used in automobiles, form implements, machines, gears and springs. The transient two-dimensional diffusion equation that represents the carbon concentration profile within the carburised-carbon steel 1024 is discretised using Alternating Direction Implicit (ADI) technique. A semi-analytical method is used to verify the ADI method and the numerical algorithm is developed in MATLAB software. To materialise the pack carburisation process, the boundary condition, initial condition and step time are encoded to signify the experiment conditions from the literature. The simulation results successfully predicted the carbon concentration profile within the carburised-carbon steel 1024 with variation of carburisation time (2 hours to 60 hours) and temperature (900°C - 1000°C). The effect of carburisation time and temperature are evaluated and the relation of both effects on the carbon development is explained. Simulation results show that carburisation extended to 60 hours only increases the carbon content at the core to 0.3wt % from 0.24 wt% of its original content. The small increment is satisfactory to maintain its ductility by hardening the surface.
      6  1
  • Publication
    Progression in the growth of cylindric nanostructures: carbon nanotubes (CNTs) and carbon nanofibers (CNFs) on graphene
    ( 2022-12) ; ;
    H.A. Hanafi
    ;
    Mishthafiyatillah
    ;
    ; ;
    Mohamad Nazri Abdul Halif
    ;
    ;
    A.F. Abd Rahim
    The combination of carbon nanotubes (CNTs) and graphene produce a CNTs-graphene hybrid material with excellent electrical and mechanical properties that improved from their single form. This CNTs-graphene hybrid material has the potential to be used as electrodes and interconnects as it has better properties compared to copper (Cu). This work intended to grow CNTs on graphene using a CVD technique. The growth process used graphene on a Cu substrate with ferrocene as the catalyst, acetone as the carbon precursor and reactor temperature of 800oC. However, the process has unintentionally grown carbon nanofibers (CNFs). To observe the progression in the growth of CNTs and CNFs on graphene, the effect of growth reaction time is crucial. Hence, this work investigates the growth progression of the CNTs and CNFs on graphene based on different reaction times of 10 min, 20 min, 30 min and 60 min. It was found that the agglomeration of carbon is incomplete at 10 min reaction time and produced cylindric nanostructures. A further reaction time of 20 min and 30 min has significantly changed the size of the cylindric nanostructures into CNTs and CNFs with a very slight difference in the size, density, and coverage. The 30 min reaction time produced denser CNTs and CNFs with more uniform size and coverages. A longer reaction time of 60 min led to very long CNFs with an average length of 120 μm. In conclusion, meticulous fine-tuning of the reaction time is required to control the formation of CNTs and CNFs on graphene.
      2  29
  • Publication
    A Review: Synthesis and Mechanism of Growth of the Carbon Nanotubes (CNTs) – Graphene Hybrid Material and its Application as Electrodes
    The CNTs–graphene hybrids have many advantages and potential for use in a wide range of electronic applications as electrodes. The CNTs–graphene hybrid structure outperforms the structure of each material in terms of characteristics and performance. There are several methods to grow CNTs. This paper reviews the chemical vapor deposition (CVD) method used to synthesize CNTs–graphene hybrid material. This paper discusses the processes and growth parameters of the synthesis of the CNTs-graphene hybrid. This paper also discusses the growth mechanism and kinetics of CNTs. In addition, the potential and performance of CNTs–Graphene hybrid material as electrodes in batteries are also reviewed.
      3  28
  • Publication
    A mini-review of coupled convection-diffusion equations in a fixed-bed adsorption
    (IOP Publishing, 2020)
    Nurhusnina Mohd Supian
    ;
    ;
    Environmental contamination triggered by dyes has gained global attention. Industrial effluent of dye in high concentration into the rivers must be reduced to minimise the harmful effect on the quality of water that threatens human health. The removal of dye from wastewater is a significant step in addressing the problem of dye emission which can be achieved through adsorption separation technologies. In the most adsorption process, the adsorbent is in contact with fluid in a fixed bed. The performance of adsorptive separation of dye can be predicted through a fixed bed mathematical model which consists of coupled partial differential equations for optimizing the design and operating conditions. This paper presents a mini-review of mathematical modelling of fixed-bed adsorption of dye. The discussions are limited to the used of single component-dye separation in, convection-diffusion equations coupled with Langmuir isotherm. Besides, the numerical methods used for solving the convection-diffusion equations are also discussed in this paper.
      2  7
  • Publication
    A review: synthesis and mechanism of growth of the carbon nanotubes (CNTs) – graphene hybrid material and its application as electrodes
    The CNTs–graphene hybrids have many advantages and potential for use in a wide range of electronic applications as electrodes. The CNTs–graphene hybrid structure outperforms the structure of each material in terms of characteristics and performance. There are several methods to grow CNTs. This paper reviews the chemical vapor deposition (CVD) method used to synthesize CNTs–graphene hybrid material. This paper discusses the processes and growth parameters of the synthesis of the CNTs-graphene hybrid. This paper also discusses the growth mechanism and kinetics of CNTs. In addition, the potential and performance of CNTs–Graphene hybrid material as electrodes in batteries are also reviewed.
      35  1
  • Publication
    A controlled growth of carbon nanofibers (CNFs) on graphene
    ( 2023-12)
    Mishtha Fiyatillah
    ;
    ; ;
    L K Wisnu Kita
    ;
    ; ;
    A F Abd Rahim
    Carbon nanofibers (CNFs) have superior properties such as high conductivity, good mechanical strength, high specific surface area, and chemical stability. CNFs-graphene hybrid material can be used as a high-quality electrode in electronics applications. In the CNFs on graphene synthesis, the growth parameters must be well controlled. This work observes the evolution of the CNF's growth on graphene on Ni at reaction temperatures of 800oC and 860oC and at different reaction times of 30 min, 60 min, and 120 min. This research aims to find suitable conditions for obtaining controllable growth of CNFs on graphene. Based on the SEM measurement, it was found that the 860oC reaction temperature at 60 min and 120 min reaction time led to longer and smaller widths of CNFs with high coverage and distribution on graphene. The CNFs on graphene formation were confirmed by the XRD analysis.
      2  30
  • Publication
    Carbon Nanofibers (CNFs) Synthesis on Graphene/Ni Thin Film: An Analysis on the Effect of Carrier Gas Flow Rate
    ( 2023-01-01)
    Fiyatillah M.
    ;
    ; ;
    Kita L.K.W.
    ;
    Jun H.Q.
    ;
    ; ;
    Abd Rahim A.F.
    The pursuit of high-performance materials for interconnects and electrodes in various electronic applications has led to the exploration of carbon nanotubes (CNTs)-graphene hybrid materials due to their potential to surpass copper (Cu) in terms of thermal conductivity. This study aimed to grow CNTs on graphene. However, the applied growth parameters led to the formation of carbon nanofibers (CNFs) on graphene. CNFs-graphene hybrids may have lower thermal conductivity compared to CNTs-graphene hybrids. This investigation aims to understand the growth evolution of the CNFs at a varied carrier gas flow rate. This work investigates the CNFs' growth on graphene on a nickel (Ni) thin film substrate under a growth temperature of 860°C in 2 hours. By varying the gas flow rate, this research aims to discern the optimal conditions for achieving controllable CNFs growth on graphene. This work found that the higher carrier gas flow rate led to better formation of CNFs with a more uniform coverage and smaller width. The XRD results confirm the formation of CNFs on graphene.
      2  27
  • Publication
    A Controlled Growth of Carbon Nanofibers (CNFs) on Graphene
    ( 2023-12-01)
    Fiyatillah M.
    ;
    ; ;
    Kita L.K.W.
    ;
    ; ;
    Abd Rahim A.F.
    Carbon nanofibers (CNFs) have superior properties such as high conductivity, good mechanical strength, high specific surface area, and chemical stability. CNFs-graphene hybrid material can be used as a high-quality electrode in electronics applications. In the CNFs on graphene synthesis, the growth parameters must be well controlled. This work observes the evolution of the CNF's growth on graphene on Ni at reaction temperatures of 800oC and 860oC and at different reaction times of 30 min, 60 min, and 120 min. This research aims to find suitable conditions for obtaining controllable growth of CNFs on graphene. Based on the SEM measurement, it was found that the 860oC reaction temperature at 60 min and 120 min reaction time led to longer and smaller widths of CNFs with high coverage and distribution on graphene. The CNFs on graphene formation were confirmed by the XRD analysis.
      3  34
  • Publication
    Enhancement of electrical conductivity of electrospun polyacrylonitrile fibres using carbon nanomaterials synthesised from polypropylene waste
    (Trans Tech Publications Ltd., 2020)
    Yong Siong Koo
    ;
    Zhun Yuan Soh
    ;
    ; ; ;
    A.N. Edzatty
    ;
    Roslan Nur Izzati
    Incorporation of carbon nanomaterials (CNMs) into polymer such as Polyacrylonitrile (PAN) fibres allow electric current to pass through easily. Therefore in this study, bulk quantities of CNMs are synthesised using Chemical Vapor Deposition (CVD) method by manipulating the reaction time and catalyst ratio. Polypropylene wastes are used as the carbon precursor and ferrocene as metal catalyst in the CVD experiment. Addition of 1 wt% synthesised-CNMs into electrospun PAN fibres successfully increased the electrical conductivity by 50%. Addition of CNMs improved the crystallinity of electrospun-PAN/CNMs fibres as proven by XRD analysis. Electrospun PAN/CNMs-A fibres show larger diameter than the diameter of electrospun PAN/CNMs-B. Large bead formations contained densely-packed CNMs-A within the structure of electrospun PAN/CNMs-A fibres hindered their effectiveness to conduct the electricity. On the contrary, PAN/CNMs-B shows remarkable improvement in electrical conductivity when loosely-packed CNMs-B are added to the PAN fibres.
      8  2