Khairel Rafezi Ahmad
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Preferred name
Khairel Rafezi Ahmad
Official Name
Ahmad, Khairel Rafezi
Alternative Name
Ahmad, Khairel R.
Ahmad, K. R.
Rafezi Ahmad, Khairel
Ahmad, Khairel Rafiez
Ahmad, Khairul R.
Khairel, R. A.
Rafezi, Khairel
Ahmad, Khairel Refazie
Ahmad, Khaireel Rafezi
Main Affiliation
Scopus Author ID
43260917000
Researcher ID
AAK-8057-2020

Research Output

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  • Publication
    Effect of sintering temperature on the preparation and characterization of green glass ceramic from rice husk ash as a matrix
    (Trans Tech Publications Ltd., 2020)
    Shahrizam Saad
    ;
    Abdullah Chik
    ;
    Khairel Rafezi Ahmad
    ;
    Sharifah Shahnaz Syed Bakar
    Powder metallurgy technique were proved successful net-shape technology which suitable for the production of green glass ceramic (GGC) from rice husk ash (RHA) and characterized by good physical and mechanical properties of glass ceramic. In this research, the glass sample was formed by mixing varying percentage of weight of silica, flux and additives. The aim of this work is to study the effect of the sintering temperature to the physical and mechanical properties of GGC. The samples were mixed in different volume fraction of additives which is 5%, 10% and 15% in constant composition of RHA and flux. The mixture was consolidated into rigid die compaction at 300MPa, then sintered at 450, 550 and 750°C. Vickers hardness test were investigated. The glass composite were then characterize by scanning electron microscopy (SEM). The GGC with 10% additives at sintering temperature 550°C shows highest hardness strength which is about 213.0 HV.
  • Publication
    Influence of heating temperature on structure, morphology and electrochemical performance of LiV₃O₈ cathode for lithium-ion batteries application
    (Trans Tech Publications Ltd., 2020)
    Mohamad Izha Ishak
    ;
    Khairel Rafezi Ahmad
    ;
    Rozana Aina Maulat Osman
    ;
    Mohd Sobri Idris
    LiV₃O₈ layered structure was successfully synthesized by a conventional solid-state approach and subsequent heat-treated at 400, 450, 500 and 550 ºC. The samples were characterized by XRD, SEM, TEM, BET. Electrochemical performance of LiV₃O₈ was investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge. The results showed that high purity of LiV3O8 with layered structure was formed. The morphology of the samples were mixed between nanorods and nanosheets structure. For electrochemical performance, results showed that LiV₃O₈ heat-treated at 500 ºC performed a highest charge and discharge capacity of 212 and 172 mAh g-1, respectively. From electrochemical performance results made them a good candidate for cathode material for lithium-ion batteries application.
  • Publication
    Facile synthesis of layered LiV₃O₈ nanosheets and their electrochemical performance as cathode materials for Li-Ion batteries
    (Springer, 2020-03)
    Mohamad Izha Ishak
    ;
    Mohd Sobri Idris
    ;
    Rozana Aina Maulat Osman
    ;
    S. M. Hasanaly
    ;
    A. H. Hashim
    ;
    M. F. Rosle
    ;
    Khairel Rafezi Ahmad
    Layered nanosheets of a LiV₃O₈ cathode material were successfully prepared via a modified solid-state synthesis. The morphological changes of the layered nanosheets of the LiV₃O₈ cathode, which resulted from preparation at different temperatures, strongly affected the electrochemical performance of this cathode material. The layered nanosheets of the LiV₃O₈ cathode prepared at 500 °C delivered the highest electrochemical performance with initial charge and discharge capacities of 212 and 175 mAh g−1, respectively, when cycled between 1.5 and 4.0 V versus Li/Li+. The particulate morphology of LiV₃O₈ showed widths in a range of 100-145 nm and lengths between 1.0 and 2.5 µm. The layered nanosheet structure contributed to the increased electrochemical performance of LiV₃O₈ as a cathode material for applications in high-energy lithium-ion batteries.
  • Publication
    Microstructural analysis of iron aluminide fabricated from iron mill scale by powder metallurgy method
    (Universiti Malaysia Perlis (UniMAP), 2010-06-09)
    S. Nurul Syuhada
    ;
    Ruhiyuddin Mohd Zaki
    ;
    Khairel Rafezi Ahmad
    This research describes the microstructural of iron aluminide which fabricated from iron mill scale by powder metallurgy method. The raw material used consists of iron mill scale and aluminum powder. Iron mill scale is obtained from steel plant company in north Malaysia. This mill scale was milled for 4 hours with grinding media to produce a fine particle size and then the mill scale was sieved into a different size. After that, the premix of iron mill scale and aluminum powder was compacted with 5.7 ton load and the process was conducted at room temperature. The green compact were subjected to sinter in condition of nitrogen atmosphere at 500ûC with 8°C/min heating rate and soaking time was set for 30 minute. The structural characteristics of sintered sample and raw material investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) methods are presented. SEM result of the sintered sample obtained at 500ûC showed that some particle of iron mill scale do not react with aluminum powder to create bonding together. This means the temperature that used for sintering do not reached the suitable sintering temperature.
  • Publication
    A review on the effect of extrusion parameter on 3D printing filament diameter
    (Springer, 2023)
    Krishna Kumar Nitiyah
    ;
    Luqman Musa
    ;
    Mohamad Syahmie Mohamad Rasidi
    ;
    Khairel Rafezi Ahmad
    ;
    Shayfull Zamree Abd. Rahim
    ;
    Rozyanty Rahman
    ;
    Ahmad Azrem Azmi
    Over the years, the extrusion technique has captured the attention of polymer industries by meeting the demand for polymer processing and fabrication of final products. Extrusion is a continuous process, and it has a lot of potential in the increasing polymer sector, especially in the three-dimensional (3D) printing sector. 3D printing is popular because the feedstock filament form is accessible and produce able. The properties of the filament used influence the printed part qualities regardless of the FDM parameters. This study provides information on how extrusion parameters affect the diameter of extruded filaments. This study reviews previous studies on the effect of varied extrusion settings on filament diameter. The review will serve as a resource for researchers in the 3D printing sector to fabricate their filaments for 3D printing. Overall, this paper will provide solutions to overcome issues in obtaining optimal filament diameters for future research projects.
      2  9
  • Publication
    Mesh refinement for cortical and trabecular bone finite element modeling: A review
    ( 2020-12-22)
    Mohd Zain, Noor Alia
    ;
    Ruslizam Daud
    ;
    Nur Saifullah Kamarrudin
    ;
    Khairel Rafezi Ahmad
    ;
    Nurul Huda A.A
    For centuries, the finite element (FE) method has been extensively used to predict the fracture performance and various method has been implemented to yield accurate results especially in healthcare industries. Bone fracture has been a critical problem since it interrupts the strength and structure of human bone. Thus, this problem will lead to bone malfunction and cause excess bleeding of surround tissues. Human bone consists of cortical and trabecular bone which serve a different amount of load sustainability before the fracture occurred. One of the most vital problems arise is the inaccuracy of the stress intensity factor related to the bone fracture. Recent studies have proven that with the implementation of appropriate meshing element produce higher accuracy results especially with the implementation of mesh refinement in the finite element model. The singularity elements suggested by Barsoum (1976) has proven that the quarter-point triangular elements give highly accurate results. Several methods for stress intensity factor calculation has been implemented by various past researchers. Among all the methods used, J-integral has proven to be the most accurate method compared to the others.The first section in your paper.
      7  31
  • Publication
    Quality and Management Planning Tools
    (Penerbit Universiti Malaysia Perlis, 2008)
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Zuraidah Mohd Zain
    ;
    Norazian Mohamed Noor
    ;
    Khairel Rafezi Ahmad
    There are numerous definition of quality. Even the most popular quality gurus have different definitions of quality. However the definitions have underlying common grounds that embody the discipline of Quality Studies. Over many years, quality practitioners gradually realized that a large number of quality- related problems can be solved using what is known as the “7 basic QC tools”. In addition, quite recently, the “7 basic QC tools” (or “7 management tools”) make their debut into the scene. These can be used in conjunction with the basic tools. Managers and engineers alike should capitalize on these tools when planning and implementing problem-solving as well as improvement projects. This book describes some quality definitions and discusses the use of both basic and new quality tools in a simple manner. It provides an uncomplicated overview for students who are starting their way in exploring quality.
      5  20
  • Publication
    Pengenalan kepada ujian bahan tanpa musnah
    ( 2013)
    Mohd Arif Anuar Mohd Salleh
    ;
    Khairel Rafezi Ahmad
    ;
    Dewi Suriyani Che Halin
    ;
    Siti Hawa Mohamed Salleh
    ;
    Muhammad Hafiz Zan @ Hazizi
    Pengenalan Kepada Ujian Bahan Tanpa Musnah merupakan sebuah buku yang membincangkan beberapa perkara asas yang penting dalam ujian tanpa musnah. Ia meliputi kebanyakan kaedah ujian tanpa musnah yang sering digunakan di industri. Buku ini memberi penerangan dalam ujian bahan tanpa musnah yang sering digunakan dalam industri bagi memeriksa kecacatan atau ketidaksempurnaan sesuatu bahan tanpa merosakkan atau memusnahkan bahan yang diperiksa. Keseluruhan kandungan buku ini merangkumi perbincangan dari aspek teori serta konsep pengujian, kaedah pengujian, dan aplikasi ujian dalam industri.
      2  939
  • Publication
    Pengenalan Bahan Komposit
    (Penerbit Universiti Malaysia Perlis, 2011)
    Khairel Rafezi Ahmad
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Che Mohd Ruzaidi Ghazali
    ;
    Shamsul Baharin Jamaluddin
    ;
    Mohamed Faisol Mohamed Nor
    ;
    Alida Abdullah
    Bahan komposit ialah satu bahan kejuruteraan yang juga dikenali sebagai ‘Bahan Termaju’ dan penggunaannya semakin meluas pada masa kini. Perkara-perkara asas seperti jenis, sifat, kaedah penghasilan dan contoh aplikasi bagi bahan komposit dibincangkan di dalam buku ini. Buku ini juga menerangkan secara terperinci tentang bahan komposit seperti komposit matriks polimer, komposit matriks logam, komposit matriks seramik dan komposit matriks simen. Dengan terhasilnya penerbitan buku ini, diharapkan dapat membantu dan menarik minat pembaca yang ingin mengetahui lebih lanjut tentang bahan komposit dalam meningkatkan pemahaman terhadap asas-asas komposit atau bahan termaju dalam kejuruteran bahan.
      28  3
  • Publication
    Recycled Incineration Bottom Ash and Metakaolin as Sustainable Materials for Cement Replacement in Cementitious Composites
    ( 2023-01-01)
    Roshazita Che Amat
    ;
    Syakirah Afiza Mohammed
    ;
    Norlia Mohamad Ibrahim
    ;
    Nur Liza Rahim
    ;
    Khairel Rafezi Ahmad
    ;
    Raischi M.
    Study was related to the influence of the concrete properties by using different percentages of metakaolin and fixed percent of incineration bottom ash to partially replace the cement. Cement is a well-known building material and used for the construction in the world. Moreover, the used of metakaolin (MK) and incineration bottom ash (IBA) in this research would give significance to our environment as it can reduce the usage of cement in concrete. By using bottom ash, it could reduce the land filling space. The X-Ray Fluorescence (XRF) test was used to determine the chemical composition of IBA and MK. Four series of concrete have been examined, including control, IBA and MK were used as partial replacement for cement at 10%IBA + 10%MK, 10%IBA + 15%MK and 10%IBA + 20%MK of concrete mixes by volume. The curing period for the samples is 7 days and 28 days. To determine the properties of concrete, the tests such as slump test, density test, water absorption test, pulse velocity test, rebound hammer test and compression test were performed. The results proved that the strength development of 10%IBA + 10%MK concrete sample shows the highest compressive strength after 28 days of curing.
      1  18