Now showing 1 - 10 of 12
  • Publication
    A Controlled Growth of Carbon Nanofibers (CNFs) on Graphene
    ( 2023-12-01)
    Fiyatillah M.
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    ; ;
    Kita L.K.W.
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    ; ;
    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  41
  • Publication
    Effect of using Palm Char and Coke as a Reductant in Production of Ferrosilicon
    This research focused on the synthesis of ferrosilicon alloy by coke and palm char as a reductant. Raw materials which were iron ore, silica sand, coke and palm char mixed and compacted into pellets. The pellets were reduced at temperature of 1300 C using horizontal tube furnace with nitrogen gas flow. The pellets after reduction process were characterized by X-ray fluorescence (XRF), X- ray diffraction (XRD), Scanning electron microscope equipped with energy dispersive spectra (SEM/EDS). The results from XRD analysis indicated that the formation of FeSi, Fe3Si and SiC phases were appeared at 1300 C for both reductants. The brighter phases were observed in SEM/EDS mapping analysis represents as iron and silicon. The EDX analysis showed the high amount silica developed for coke compared to palm char due to high content of silica and carbon. The results found that palm char as carbon reductant has the potential to produce ferrosilicon and silica carbide in sustainable way.
      7  31
  • Publication
    Structural Characterizations and Phase Transition on the Reducibility of Ilmenite Ore with Different Carbon Reductants by Carbothermal Reduction Under Hydrogen Atmosphere
    ( 2023-12-01) ; ;
    Nasrun N.A.
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    Kurniawan A.
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    Nomura T.
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    Rezan S.A.
    This research focused on investigating the properties and phase transition of ilmenite ore with various carbon reductants by performing a carbothermal reduction, followed by a hydrogen reduction (Ar:H2) at 900–1000 Â°C to extract rutile from the ore. To comprehend the impact of the carbon structure and characteristics on the reduction performance and incorporate a thermodynamic assessment during reduction reactions, two distinct carbon reductants: graphite (GI) and renewable carbon from palm char (PI), were selected. The phase transitions and reduced samples were examined using both qualitative and quantitative X-ray diffraction. The results revealed that ilmenite ore transformed into pseudobrookite ferrous (FeTi2O5), titanium trioxide (Ti3O5), rutile (TiO2), and iron (Fe) after carbothermal reduction at 1550 Â°C where brookite (TiO2) and anatase (TiO2) peaks were diminished. As the temperature rose during the secondary reduction by hydrogen, the reduction reaction sequenced as follows: FeTi2O5 → Ti3O5 → Ti2O3 → TiO2 and Fe. Due to the carbon structure and superior characteristics, the reduced PI demonstrated a greater degree of TiO2 reduction (81.8%) than the reduced GI (74.8%) at the highest reduction temperature of 1000 Â°C. In the early and middle stages of the reaction at high temperatures, the carbothermal reduction of ilmenite ore with solid carbon and CO participated and produced rutile, iron, and Ti3O5, whereas, in the latter stages, rutile, iron, and Ti2O3 are mostly formed when reduced by hydrogen. In conclusion, employing palm char with hydrogen atmosphere to extract pure rutile from ilmenite ore might be accomplished by using these proposed methods. Graphical Abstract: [Figure not available: see fulltext.]
      1  24
  • Publication
    Near surface studies on the role of graphene oxide in the carbon species activities in it-sofc cathode materials
    Active roles of carbon species in solid oxide fuel cell (SOFC) cathode was simulated by adding graphene oxide (GO) into Ba0.5Sr0.5Co0.2Fe0.8 (BSCF) materials prepared by sol-gel method. The mixture was heated up to intermediate temperature SOFC range (650 – 850 °C) for a period of 5 hours. A depth-profiling measurement by x-ray photoelectron spectroscopy (XPS) technique was carried out to analyse the carbon species activities at near surface of BSCF cathode. A depth-profiling analysis indicated that the GO bond components are retained under the cathode surface and does not affected the formation of carbonate phases in BSCF cathode.
      4  25
  • 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.
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    ; ;
    Kita L.K.W.
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    Jun H.Q.
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    ; ;
    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.
      3  40
  • Publication
    The Correlation between Palm Shell Char Properties and the Production of Metallic Iron in EAF Steelmaking Slag Reduction Reaction
    Palm shells wastes generated from oil palm processing are in abundance in landfills every year thereby posing environmental problems. Enormous amount of wastes generated by agro-industry has previously studied as carbon source in steelmaking hence providing solution to environmental problems. This paper studied on the conversion of palm shell waste into carbon material via physical and chemical activation method for metallic iron extraction. Physical char was prepared by pyrolyzed in nitrogen atmosphere at 450°C while chemical char was impregnated in phosphoric acid before pyrolyzed. Composite pellets of EAF slag (43.18 %Fe2O3) with physical and chemical char were rapidly heated at temperature 1550°C within 20 minutes under argon flow. All reduced samples were analyzed on the weight loss, degree of reduction, iron recovery and phase analysis using X-ray diffraction (XRD). The results indicated that chemical/slag showed higher weight loss (38.8%) and excellent degree of reduction (29.94%) compared to physical/slag due to higher volatile matter content (9.8%) and larger surface area (562.14m2/g). It was found that the production of metallic iron particles after the reduction process and indicated that chemical char achieved higher iron recovery (15.48%) compared to physical char due to higher total carbon content (60.28%). XRD and Rietveld refinement analysis confirmed that the iron phase was a major component in metallic iron particles for physical/slag and chemical/slag samples. This elucidated that the iron oxides in EAF slag was completely reduced into iron by using palm shell chars as carbon materials. This finding indicates that palm shell chars potentially act as carbon materials in steelmaking applications according to their good characteristics.
      5  20
  • Publication
    Investigation on Phase Evaluation of Ilmenite Ore by Carbothermal Reduction and Carboiodination Reaction
    ( 2023-12-01)
    Adel A.A.
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    ; ;
    Togang L.I.G.
    This article presented the thermochemical calculation and experimental investigation on the phase evaluation of ilmenite ore (FeTiO3) via carbothermal reduction and carboiodination reaction for titanium production using graphite as a reducing agent. The carbothermal reduction and carboiodination reactions were performed in two different furnaces. The carbothermal reduction was evaluated at a temperature of 1550°C with inert argon gas utilizing a horizontal tube furnace. The carboiodination reactions were evaluated in temperatures ranging from 900°C, 950°C, and 1000°C using a vertical tube furnace with mixed iodine gas with argon gas. XRF and XRD were used for analyzing the chemical compositions and the phase evolutions of raw ilmenite ore and the reduced samples, respectively. The findings showed that the Perak ilmenite ore predominantly has a greater concentration of TiO2 (71.27wt%), Fe2O3 (18.85wt%), and some other oxides like aluminum oxide and quartz. In addition, XRD revealed that the ilmenite phase was converted into rutile (TiO2) titanium oxide (Ti3O5, Ti2O3), titanium carbide (TiC), and iron (Fe) phases, after the carbothermal reduction process. However, after the carboiodination reaction, the ilmenite and rutile phases remained at temperatures 900°C, 950°C, and 1000°C. The HSC Chemistry software was used in the determination of the thermochemical calculation and the possible reactions during the reaction which play an important role in shortening the reduction process. The results revealed the carboiodination process is a promising process that can reduce energy consumption and shorten the titanium production processes, and it needs more studies.
      1  23
  • Publication
    Phase transformations of Langkawi ilmenite ore during carbothermal reduction using palm char as renewable reductant
    ( 2022-02-01)
    Mohammed A.I.
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    ; ;
    Nur Hazira Najmi
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    ;
    Nomura, Takahiro
    The phase transformations of carbothermal reduction of Langkawi ilmenite ore by palm char were studied in reduction temperatures ranging from 1200 °C, 1300 °C, and 1400 °C using a horizontal tube furnace with inert argon gas. The palm shells as renewable carbon reductant for carbothermal reduction of ilmenite ore were converted into palm char using pyrolysis techniques to improve and increase the surface area and carbon content. The present study aims to reduce oxides in ilmenite ore from our local mining to produce titanium oxides by carbothermal reduction process and recycled agricultural waste from palm shell as renewable reductant. The phase and chemical compositions of ilmenite ore and reduced samples were analyzed by XRD and XRF. It was found that ilmenite ore mainly contained titanomagnetite, hematite, and titanium dioxide phases. After carbothermal reduction, the titanomagnetite phase from ilmenite ore was transformed into titanium dioxide, iron titania, iron, and titanium carbide at the highest reduction temperature (1400 °C) via XRD analysis. The phase transformation revealed the porous structure with wider pore size distribution and high carbon from palm char was able to reduce the oxides in ilmenite ore. According to XRF analysis, the TiO2 amount was increased with the temperature; from 25.7 wt.% at 1200 °C up to 50.8 wt.% with the extent of reduction of TiO2 was 78.56% at 1400 °C. The carbothermal reduction of ilmenite ore using palm char as a renewable reductant was possible and promising in mineral ore extractions.
      6  10
  • 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.
      4  34
  • Publication
    Prediction of maximum spreading time of water droplet during impact onto hot surface beyond the Leidenfrost temperature
    ( 2021-12-01) ; ;
    Rahim Y.A.
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    ; ;
    Ismail K.A.
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    Ani M.H.
    When a water droplet impacts on a heated surface in the film boiling regime, it will spread, recede, and finally bounce off from the heated surface. These unique liquid-solid interactions only occur at high surface temperatures. Our main objective in this research is to measure the maximum spreading and residence time of the droplet and the findings were compared to theory. We focused our study in the film boiling regime. Brass material was selected as the test surface and was polished until it became a mirror polished surface. The temperature range for this experimental work was between 100 °C up to 420 °C. Degassed and distilled water was used as the test liquid. The high speed video camera recorded the images at the rate of 10,000 frames per second (fps). As a result, it was found that the experimental value of maximum spreading and residence time agreed closely with the theoretical calculation. A new empirical formula that can be used to predict the maximum spreading time in the film boiling regime is also proposed.
      1  29