Banjuraizah Johar
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Preferred name
Banjuraizah Johar
Official Name
Banjuraizah, Johar
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Scopus Author ID
36782257500
Researcher ID
ELA-9787-2022

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Impact of secondary phases content on the mechanical properties of cordierite

2017-01-01 , Eing Kuan Kok , Banjuraizah Johar , Ho Li Ngee , Zabar Yahidah

The Cordierite ceramic body had been synthesized through conventional techniques solid state reaction by using non-stoichiometric composition (2.5 MgO. 1.8 Al2O3. 5 SiO2). The sintering temperature study was carried out by heat treated the samples at several degree of sintering temperature (1250 °C, 1275 °C, 1300 °C, 1325 °C, 1350 °C and 1375 °C). The qualitative and quantitative of crystalline phase analysis was accomplished by using X-ray Diffraction (XRD) technique and Rietveld structural refinement. The Scanning electron microscopy (SEM) was employed for morphology analysis. The mechanical properties of samples were determined by Vicker's Hardness test. Rietveld quantitative phase analysis results show that α phase Cordierite constitutes up to 96.4 wt% when the samples was sintered for 2 hours at sintering temperature of 1375 °C and obtained densified and orderly crystal structure arrangement in SEM micrograph except the mechanical strength. The sample obtained the uppermost α phase Cordierite content gained the lowest hardness values (4.0±0.8GPa). Conversely, the sample contains 90 wt% α-cordierite and 1.4 wt% magnesium titatnate achieve highest hardness which is about 4.9±0.79GPa.

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The Microstructural and Bioactivity Behavior of Magnesium Alloy Filled with Bioglass for Biomedical Application

2022-01-24 , Nur Maizatul Shima Adzali , Dahlan N.F. , Banjuraizah Johar , Baharom N.A.

Magnesium alloy have known as degradable implant material due to biodegradable properties. However, by developed Mg alloy matrix composites containing a bioceramic will produced more biodegradable and does not need second surgical to remove the implants in body. Powder metallurgy route was used to fabricate the AZ91/BG composite by mixing, compacting and sintering. Mg alloy (AZ91) was reinforced with 0, 3, 6, and 9 wt% of bioglass (BG) before compact and sintered at 400°C for 2 hours. The Vickers hardness, scanning electron microscope, and x-ray diffraction are used to investigate the effect of BG particles addition on the mechanical properties and microstructure of the composite AZ91/BG. Bioactivity behaviour was studied by immersion test of AZ91/BG composite into phosphate buffered saline (PBS) solution for 72 hours. The results showed that as the addition of BG increases from 3 to 9 wt%, the hardness of AZ91/BG decrease from 43.3HV to 27.9HV. The result also showed the formation of protective layers or apatite layer on the surface of AZ91/BG composite after immersed in PBS solution for 72 hours. Phase analysis by XRD shows the presence of peak Ca10(OH)2(PO4)6 as the BG increased from 3 to 9 wt%. As a conclusion, AZ91/3BG shows the optimum composite for biomedical application based on its properties and bioactivity behaviour.

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Dielectric properties of Nephelium Lappaceum tropical wood

2020-03-25 , Khor Shing Fhan , Cheng Ee Meng , Banjuraizah Johar , Nashrul Fazli Mohd Nasir , Zaizul M.A. , Wan Azani Wan Mustafa , Nik Noriman Zulkepli , Dahham O.S.

Dielectric properties of rambutan wood (Nephelium Lappaceum) were investigated in three anisotropic directions, namely miters-cut, cross-cut, and rib-cut. Dielectric constants and dielectric loss factors were measured at ambient temperatures by using an impedance analyzer. The dielectric constant decreased as frequency increased from 4 to 1 MHz. Among the wood specimens, the rib-cut direction has the lowest dielectric constant, while the cross-cut direction has the highest value. A dielectric dispersion occurred within frequencies 100 Hz to 10 kHz, which corresponding to a relaxation peak as observed on dielectric loss factor spectra. The relaxation peak value of the dielectric loss factors shifted towards higher frequencies in the sequence of rib-cut, miters-cut, and cross-cut specimen. Above 500 Hz, the cross-cut specimen has the highest value conductivity than others. Generally, these variations were subjected to the anatomical structure in the wood, such as parenchyma, ray cell, vessel cell, and fiber cell.

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Phase Analysis of Bio-Based Derived Tricalcium Disilicate From 2CaO:1SiO2 By X-ray Diffraction

2021-12-14 , Siti Nur Hazwani Yunus , Fhan K.S. , Banjuraizah Johar , Nur Maizatul Shima Adzali , Jakfar N.H. , Cheng Ee Meng

In this paper, tricalcium disilicate was formed from dicalcium silicate compound powder, synthesised via a mechanochemical technique using a stoichiometric 2CaO:1SiO2. Compound CaO and SiO2 were derived from the bio-waste of eggshell and rice husk at the calcination temperature of 900oC and 800oC, respectively. The dicalcium disilicate powder was sintered for 2 hours at different temperatures ranging from 1150oC to 1350oC. Using X-ray diffraction with Rietveld analysis, it was found that the amount of tricalcium disilicate with monoclinic (beta) crystal structure increases on sintering temperature at the expense of dicalcium silicate. The complete formation of single-phase tricalcium disilicate began at a sintering temperature of 1300oC. The effect of sintering temperatures on the crystallisation and phase transition of dicalcium silicate is reported. The size of crystallites depends on the sintering temperature. The finding of this study rebound to the benefit of society by reducing the risk-off pollution cause by accessive redundant bio-waste eggshell and rice husk and also reduced the amount of CaO and SiO2 used in the fabrication of Ca3Si2O7

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UVA-irradiated dual photoanodes and dual cathodes photocatalytic fuel cell: mechanisms and Reactive Red 120 degradation pathways

2022-11-01 , Ong Y.P. , Ho Li Ngee , Ong S.A. , Ibrahim A.H. , Banjuraizah Johar , Thor S.H. , Lee S.L. , Teoh T.P.

To enhance dye removal and energy recovery efficiencies in single-pair electrode photocatalytic fuel cell (PFC-AC), dual cathodes PFC (PFC-ACC) and dual photoanodes PFC (PFC-AAC) were established. Results revealed that PFC-AAC yielded the highest decolorization rate (1.44 h−1) due to the promotion of active species such as superoxide radical (•O2−) and hydroxyl radical (•OH) when the number of photoanode was doubled. The results from scavenging test and UV-Vis spectrophotometry disclosed that •OH was the primary active species in dye degradation of PFC. Additionally, PFC-AAC also exhibited the highest power output (17.99 μW) but the experimental power output was much lower than the theoretical power output (28.24 μW) due to the strong competition of electron donors of doubled photoanodes to electron acceptors at the single cathode and its high internal resistance. Besides, it was found that the increments of dye volume and initial dye concentration decreased the decolorization rate but increased the power output due to the higher amount of sacrificial agents presented in PFC. Based on the abovementioned findings and the respective dye intermediate products identified from gas chromatography-mass spectrometry (GC-MS), the possible degradation pathway of RR120 was scrutinized and proposed.

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Effect of alteration ratios of magnesia and alumina in non-stoichiometric cordierite composition formulations (2.(8-n)MgO.1.(5+n)Al2O3.5SiO2) on phase transformation and crystallization

2017-01-01 , Eing Kuan Kok , Banjuraizah Johar , Ho Li Ngee , Zabar Yahidah

This study focus on synthesis of α-phase cordierite using different non-stoichiometric cordierite composition through solid state reaction by adjusting the ratio of magnesia, MgO and alumina, Al2O3 in the cordierite composition formulation respectively. The qualitative and quantitative of phase analysis was carried out by X-ray diffractive (XRD) technique and Rietveld structural refinement method. Differential thermal analysis (DTA) was employed to investigate the crystallization behavior of various cordierite formulations as the function of temperature. The scanning electron microscopy (SEM) was also performed. Cordierite with formulation of 2.5 MgO1.8Al2O3.5SiO2 constitutes up to 96.4 wt% when the samples was sintered for 2 h at the optimal temperature of 1375 °C. The SEM micrograph revealed that the approaching single α-Cordierite sample obtained densified body with well alignment of crystal structure.

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Effect of sintering temperature on dielectric and electrical properties of bio-waste derived beta-dicalcium silicate

2023-11-01 , Mohd Yunus S.N.H. , Khor Shing Fhan , Banjuraizah Johar , Nur Maizatul Shima Adzali , Jakfar N.H. , Cheng Ee Meng , Mohd Tarmizi E.Z. , Talib Z.A.

Beta-dicalcium silicate ceramics were synthesized by mechanochemical-assisted solid-state reaction route using rice husks and chicken eggshells as silica and calcium oxide sources. The ceramics were sintered at 900, 1000, and 1100 °C for 2 h in air. The effect of sintering temperature on these ceramics' morphological, breakdown strength, dielectric, and electrical properties was investigated. It was found that the ceramic sintered at the optimized temperature of 1100 °C formed the pure β-dicalcium silicate (β-Ca2SiO4). Scanning electron micrographs showed that with the increase in sintering temperature, the average grain size and pore size of the sintered ceramics increased while the grain boundary density decreased, which promoted the breakdown path and resulted in a decrease in breakdown strength. The dielectric behavior examined from 25 to 300 °C and in a frequency range of 4–5 MHz found that the dielectric constant and loss tangent decreased with increasing frequency. Nyquist plot of impedance confirmed a non-Debye type relaxation, and grain and grain boundary contributions were revealed from equivalent circuit fitting. Variations of impedance spectroscopy reflect the positive and negative temperature coefficient of resistance behavior for these ceramics. Electric modulus spectra revealed that with the sintering temperature increase, the samples' conductivity activation energies increased from 0.35 to 0.46 eV. All the sintered samples attained low dielectric loss (0.004 < tanδ < 0.1) above 103 Hz, which makes them suitable materials for capacitor application.

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Formation of bio-based derived dicalcium silicate ceramics via mechanochemical treatment: physical, XRD, SEM and FTIR analyses

2023-07 , Siti Nur Hazwani Yunus , Khor Shing Fhan , Banjuraizah Johar , Nur Maizatul Shima Adzali , Nur Hazlinda Jakfar , Cheng Ee Meng , Emma Ziezie Mohd Tarmizi , Zainal Abidin Talib

Beta-dicalcium silicate plays an important role in modern technology, but its tendency for polymorphic transformation results in the dusting phenomenon, is a major challenge. Therefore, mechanochemical treatment is used to reduce the particle size to retain the stability of the polymorph. In this study, pure dicalcium silicate ceramics of β-monoclinic structure with P 121/c1 space group were synthesized using calcium oxide and silicate powders derived from calcined eggshells and rice husks, respectively. The powders were mixed in a 2:1 molar ratio by mechanochemical treatment and heat-treated in the air at temperatures ranging from 900°C to 1100°C for 2 h. The results reveal that pure betadicalcium silicate formed at 1100°C without adding stabilizers. The properties of the pristine and sintered bodies were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). SEM revealed that the grain and pore sizes increase with rising sintering temperatures. FTIR spectra indicate the existence of Si-O bonds in -4 4 SiO tetrahedrons on all the samples. The sample sintered at 1000°C attains the lowest bulk density (1.2463 g/cm3), whereas the apparent porosity is the highest (62.5%). The reason for this trend is due to the decomposition of carbonate into CO2 gas. The densification onset for the sample sintered at 1100°C as the bulk density rises and grain size achieves 6.06 μm. This study further explains the effect of sintering temperatures on the physical, structural, and morphological properties of Ca2SiO4 which would also be useful for further optimization of its use.

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Comparative study of different polyatomic ions of electrolytes on electricity generation and dye decolourization in photocatalytic fuel cell

2020-10-01 , Ong Y.P. , Ho Li Ngee , Ong S.A. , Banjuraizah Johar , Ibrahim A.H. , Lee S.L. , Nordin N.

Developing an effective interface interaction between photoanode and electrolyte is crucial for achieving superior photocatalytic fuel cell (PFC) performance. In this aspect, the contribution of the medium or electrolyte properties in the PFC system such as dye concentration, ionic nature and active radicals play a decisive role. Herein, we constructed a PFC with ZnO loaded nickel foam (ZnO/Ni) photoanode to study the influence of initial dye concentration, pH and supporting electrolytes of different polyatomic anions on the PFC performance. The optimum initial dye concentration and pH for the PFC with reactive red 120 as organic pollutants were found to be 30 mg L−1 and 7.5, respectively. The PFC performance can be synergistically enhanced by the addition of three types of polyatomic anions (Na3PO4, Na2SO4 and NaNO3) as supporting electrolytes. In turn, PO43- had the greatest influence on the reduction of internal resistance (highest short circuit current, Jsc) which corresponded to the conductivity of dye solution. Eventually, the higher charge of polyatomic ions could contribute to higher energy conversion efficiency in PFC. Nonetheless, SO42- anions favoured the cleavage of aromatic compounds by the advantage of recycling between SO42- and SO4[rad]- through hole scavenging activity. Comprehensively, our findings provided new insight into the selection of supporting electrolyte as well as the proposed mechanism of active radicals involved in PFC. Additionally, the ZnO/Ni photoanode demonstrated its excellent recyclability as it retained high PFC performance after five consecutive runs.

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Formation of Bio-based Derived Dicalcium Silicate Ceramics via Mechanochemical Treatment: Physical, XRD, SEM and FTIR Analyses

2023-07-01 , Yunus S.N.H. , Khor Shing Fhan , Banjuraizah Johar , Nur Maizatul Shima Adzali , Jakfar N.H. , Cheng Ee Meng , Tarmizi E.Z.M. , Talib Z.A.

Beta-dicalcium silicate plays an important role in modern technology, but its tendency for polymorphic transformation results in the dusting phenomenon, is a major challenge. Therefore, mechanochemical treatment is used to reduce the particle size to retain the stability of the polymorph. In this study, pure dicalcium silicate ceramics of β-monoclinic structure with P 121/c1 space group were synthesized using calcium oxide and silicate powders derived from calcined eggshells and rice husks, respectively. The powders were mixed in a 2:1 molar ratio by mechanochemical treatment and heat-treated in the air at temperatures ranging from 900°C to 1100°C for 2 h. The results reveal that pure beta-dicalcium silicate formed at 1100°C without adding stabilizers. The properties of the pristine and sintered bodies were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). SEM revealed that the grain and pore sizes increase with rising sintering temperatures. FTIR spectra indicate the existence of Si-O bonds in tetrahedrons on all the samples. The sample sintered at 1000°C attains the lowest bulk density (1.2463 g/cm3), whereas the apparent porosity is the highest (62.5%). The reason for this trend is due to the decomposition of carbonate into CO2 gas. The densification onset for the sample sintered at 1100°C as the bulk density rises and grain size achieves 6.06 μm. This study further explains the effect of sintering temperatures on the physical, structural, and morphological properties of Ca2SiO4 which would also be useful for further optimization of its use.-4 SiO4.

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