Nur Hidayah Ahmad Zaidi
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Nur Hidayah Ahmad Zaidi
Official Name
Nur Hidayah, Ahmad Zaidi
Alternative Name
Zaidi, Nur Hidayah Ahmad
Ahmad Zaidi, N. H.
Ahmad Zaidi, Nur Hidayah
Zaidi, N. H.Ahmad
Zaidi, N. Hidayah A.
Zaidi, N. H.A.
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37012813200

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  • Publication
    Analysis of Thermal Comfort Among Workshop Users: At TVET Technical Institution
    ( 2024-02-01)
    Alias N.M.
    ;
    Umar Kassim
    ;
    Sinar Arzuria Adnan
    ;
    Nur Hidayah Ahmad Zaidi
    ;
    Siti Nurul Aqmariah Mohd Kanafiah
    ;
    Yusoff M.N.
    ;
    Sk Muiz Sk Abdul Razak
    Thermal comfort is a part of indoor environmental quality that should be considered to ensure the occupants' well-being. Unconducive buildings not only bring occupants discomfort but also tend to affect health, disrupt the process of teaching and learning, and reduce work productivity. Thus, this study determines the thermal condition of existing workshop buildings used in Technical and Vocational Education and Training (TVET) implementation. ASHRAE Standard 55 (2017) is referred to in the determination of thermal comfort involving objective measurements and subjective measurements. Observation methods of environmental variables such as air temperature, radiant temperature, air velocity, relative humidity is observed. Evaluations of comfort are based on occupant surveys and environmental measurements. A total of 257 people completed a questionnaire distributed at three technical institutions in Kedah, Malaysia. According to the findings, the average thermal sensation vote is 1.85, which leads to 66.5% of respondents feeling discomfort. Meanwhile, the adaptive model analysis showed that the workshop environmental conditions were out of the comfort zone and did not comply with the ASHRAE 55 standard. Hence, the thermal discomfort factors from the occupants' perspective were identified and widely discussed. As a result, the research findings will benefit parties involved in new building construction or existing building renovations to improve indoor air quality.
  • Publication
    The effects of henna fillers on the properties of polyurethane foam composites
    ( 2020-01-01)
    Adnan S.A.
    ;
    Zainuddin F.
    ;
    Nur Hidayah Ahmad Zaidi
    ;
    Zulkeply N.A.
    ;
    Nur Maizatul Shima Adzali
    ;
    Zuraidawani Che Daud
    Polyurethane (PU) foam were produced from polyol (PolyGreen R3110) and 4,4-diphenylmethane diisocyanate (Maskiminate 80) with distilled water as a blowing agent. Natural fibers have received more attention from researchers due to their ability to increase the properties of the polymer composites. In this work, PU/Henna foam composites were prepared by used Henna fibers at different loading of 5, 10, 15 and 20 wt. %. The effect of different Henna loading on PU foam were investigated by density, compression test, morphology and water absorption. Core density of PU/Henna foam composites increased with addition Henna compared to control PU and showed highest core density of 85.10 kgm-3 . Compressive strength decreased to 0.53 MPa after Henna addition at 5 % PU/Henna foam composites. Henna addition to 20 % PU/Henna foam composites were reduced the compressive strength to 0.97 MPa due to stiffness effect of Henna that contributed to embrittlement of the cell wall. The distorted cell wall and less uniform of cell structure were proved by SEM due to Henna addition as compared to control PU. Water absorption percentage of PU/Henna foam composites were increased with Henna addition as compared to control PU. It is because hydrophilic properties of Henna tendency to absorb moisture.
  • Publication
    The effect of aging time on microstructure and hardness value of AZ80 Mg Alloy
    ( 2020-11-24)
    Zuraidawani Che Daud
    ;
    Azahar S.H.
    ;
    Mohd Nazree Derman
    ;
    Nur Maizatul Shima Adzali
    ;
    Nur Hidayah Ahmad Zaidi
    ;
    Adnan S.A.
    AZ 80 Magnesium (Mg) alloy (AZ80) is the lightest structural metallic materials with good mechanical properties. However, Mg AZ80 has drawbacks which result in poor ductility and low strength where applications of Mg alloy have been restricted. The AZ80 has high aluminium content can cause the precipitation of ß-phase which is Mg17Al12 in Mg-Al alloy. It can affect the mechanical properties such as poor strengthening. This paper was discussed the effect of aging time on microstructure and hardness value of AZ80. The AZ80 samples were cut to 1cm × 1cm. Samples heat treated at 360 C for one-hour quenching in water. Then, samples aged at 170 C with different aging times (2 to 8 hours) with same quench. Optical Microscope (OM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Vickers Microhardness machine were used to analyse the samples. As the results showed ß-Mg17Al12 phase was discontinuously distributed along the grain boundary throughout solid solution treatment. The ß-Mg17Al12 phase did not fully dissolve into the α-Mg phase and distributed along the grain boundary. The results showed that sample after 2 hours aging time with highest hardness value 62.5 HV is the optimum sample.
  • Publication
    Effects of Heat Treatment on the Properties of SS440C for Blades Applications
    ( 2023-01-01)
    Nur Maizatul Shima Adzali
    ;
    Salihin S.K.
    ;
    Nur Hidayah Ahmad Zaidi
    SS440C steel is commonly used for knife blades, bearings, valve parts, and medical equipment. The composition of SS440C steels is designed to increase hardness especially in blade applications. The effect of quenching and tempering heat treatment on the properties of SS440C was investigated in this study. Quenching heat treatment is done at 1000 Â°C, followed by tempering at 150 and 500 Â°C in a muffle furnace. Microstructure of SS440C samples were studied using an optical microscope (OM) and scanning electron microscope (SEM). Properties of SS440C after heat treatment have been investigated using the Rockwell hardness test and tensile test. It was found that the sample quenched at 1000 Â°C (without temper) had the highest hardness with 58.4HRC, while the as-received annealed sample had 11.4HRC followed by sample tempered at 150 Â°C with 57.5HRC and 500 Â°C with 54.1HRC. Tensile testing reveals that quenching and tempering at 500 Â°C result in the highest maximum stress compared to other samples. Through optical microscopy observation, a sample tempered at 500 Â°C has larger size of carbide precipitate than sample that quenched and tempered at a 150 Â°C. Insufficient carbide dissolution or a more abrasive reaction is revealed by larger carbide sizes. In conclusion, SS440C temper at 500 Â°C reflects that it has better properties than the other.
  • Publication
    Heat treatment of ss 316l for automotive applications
    ( 2020-01-01)
    Nur Maizatul Shima Adzali
    ;
    Azhar N.A.
    ;
    Zuraidawani Che Daud
    ;
    Nur Hidayah Ahmad Zaidi
    ;
    Adnan S.A.
    Stainless steel 316L (SS 316L) is a low carbon-chromium-nickel-molybdenum austenitic stainless steel. Its application in automotive industry include as exhaust housings for catalytic converters and turbocharger. In this research, the tempering heat treatment was conducted by using SS 316L samples. These steels were austenitized at 860 °C for 1 hours before doing two tempering process. Austempering was conducted at 360 °C for 15 min in the muffle furnace then air cooled while martempering was conducted at 160 °C for 15 min in a muffle furnace then quench in water. The corrosion test was carried out using 1.0 M oxalic acid solution for 30 days in room temperature. Hardness test and microstructural observation were carried out for SS 316L before and after corrosion test. Experimental result showed that untreated sample have highest hardness value before and after corrosion test which were 232 HV and 225 HV respectively. The hardness value before corrosion test is 199.7 HV for austempered sample, and 201.3 HV for martempered sample. Untreated sample shows the lowest corrosion rate (0.94×10-3 mpy), followed by austempered sample (1.89 x 10-3 mpy) and the highest corrosion rate is for martempered sample (2.36×10-3 mpy). After corrosion, under optical microscope observation, martempered steel has more pits than austempered steel. In summary, austempering is the best heat treatment for SS 316L in automotive applications that give high ductility and toughness after heat treatment with high corrosion resistance.
  • Publication
    Hybrid System Methods in Industrialised Building Systems (IBS): A Structural Compatibility Study
    ( 2024-11-01)
    Azmin I.
    ;
    Umar Kassim
    ;
    Sinar Arzuria Adnan
    ;
    Nur Hidayah Ahmad Zaidi
    ;
    Siti Nurul Aqmariah Mohd Kanafiah
    ;
    Yusoff M.N.
    ;
    Abd Razak S.M.S.
    ;
    Ilpandari I.
    Hybrid System in Industrialised Building System (IBS) is combining IBS components with conventional method. Delay has become a familiar issue in construction field. The issues pertaining structure stability when using this combination method leads to delay while installing these two different method components. The combination also could cause a defect jointing. In Industrialised Building System (IBS), even though it is one of the technology methods that can save times, cost, and reduce labour in construction, but there still have constraints such as design issues, lack of experienced worker, and internal and external issues that can affect cost problems. In this study, the suitability structure based on combination method is investigated to discover the affected factors of suitability structure by using Hybrid System which is the aim of this study. The data analysis from quantitative survey shows that the top three affecting the building structure are: 1) weather effects with highest mean of 6.25 followed by 2) delay of jointing process at 6.03 and 3) defects from monolithic jointing at 5.93. Therefore, the amount of average data obtained shows that the most affected structure is the Hybrid System.
  • Publication
    Fabrication and properties of Cobalt-Chromium implant composite
    ( 2007)
    Nur Hidayah Ahmad Zaidi
    Cobalt implant composite (CIC) was produced by powder metallurgy technique. Composition of 0% ,5%, 10%, 15% and 20% of hydroxyapatite was mixed with cobaltchromium alloy. The fabrication technique is mixing, blending, pressing and sintering of the final product. Cobalt, chromium and hydroxyapatite powders were mixed in planetary ball mill at 600 rpm for 30 minutes. The consolidation method for CIC was uni-axial compacting using Universal Testing Machine (UTM) Gotech. The pressure used was 500 MPa. The CIC was sintered at 10000C temperature with 200C/min for 3 hours. The composites then were evaluated and tested to evaluate the microstructure and mechanical properties. The microstructure analysis is carried out by using the Scanning Electron Microscope and Image Analyzer attached to the optical microscope. In microstructure analysis, there are several characteristics need to observe i.e., particle sizes, porosities, mode of shapes, corrosion behaviours and bonding between mixed particles and fracture mechanism, which these can describe the composites material in details. The properties such as hardness, density, and particle sizes distribution, purity of raw materials, compressive strength and corrosion behaviours are analyzed by using Vickers Micro Hardness, AccuPyc 1330 Gas Pycnometer, MALVERN MASTERSIZER 2000 particle analyzer, X-Ray Diffraction (XRD), Compression test and Immersion Fluid test in Natrium Chloride (0.9%.NaCl ), respectively. From the microstructure analysis of the composite, the microstructure indicates the homogenous distribution of the chromium particles, and HAP particles are distributed homogenously in the matrix cobalt chromium. From the X-ray diffraction (XRD) the high peak of the x-ray analysis is indicating the purity of each powder such as chromium and cobalt. In general cobalt and chromium peaks occur at the range of 40 to 50 degree and there is no obvious sign of HAP signal in XRD analysis of the composites. Both experimental and theoretical density graphs have shown a similar pattern line which both experienced the density gradually decreased when percentage of HAP increased. The hardness of the composites decreases slightly with the increasing weight percent of HAP. The sonic modulus analysis, indicating that there is a reciprocate relationship between modulus and sound velocity, whereby modulus will be decreased when the sound velocity increases. The microstructure analysis on compression test, indicated the deformation behavior of the composite started to change from the ductile mode to the brittle mode resultant with the added of HAP. Besides, the crack pattern showed non continuously for the ductile mode behavior and had a continuous line for the brittle mode behavior. Corrosion study indicated that composites experienced more corrosion when the HAP was added.
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  • Publication
    Identification of ageing behavior of Mg-Al-Zn and AZ91 reinforced carbon nanotube at nlevated temperature
    ( 2021)
    Nur Hidayah Ahmad Zaidi
    Magnesium alloys are potential composite materials that can be applied for lightweight structural engineering applications due to its specific strength in mechanical and physical properties. However, these composite materials lose its strength and creep resistance properties when exposing at certain temperature. It is reported that by adding minor alloy AZ91 and composite AZ91 with reinforced carbon nanotubes (CNT) will improve its mechanical and physical properties. Nevertheless, the work on the effects of heat treatment and prediction of ageing behaviour properties and activation energy of AZ91 and composite AZ91 reinforced with CNT still less and potential to be explored. Mg-Al-Zn (AZ91) and composite AZ91 reinforced with carbon nanotube (CNT) were fabricated using powder metallurgy method. The composite samples were varied with the weight percent of CNT with 0, 0.3, 0.6 and 0.9 wt.%. The samples were mixed via planetary mill for 20 hours and compacted at 400 MPa, pallet shape with diameter 12 mm. All samples undergo sintering at 450 ˚C then undergo T4 heat treatment (solution treatment) at 415 °C and T6 (artificial ageing) at 175 °C, 210 °C and 300 °C. Microstructure of AZ91 and AZ91+ CNT composites were observed by using an optical microscope (OM) and Scanning Electron Microscope (SEM). All samples AZ91 and AZ9+CNT composites were undergone phase analysis by using X-Ray Diffraction (XRD). Meanwhile physical properties were characterized using pycnometer instrument to determine the density of the samples. Mechanical properties studies were performing by using Rockwell hardness test and compression test via Universal Testing Machine (UTM). Finally, the activation energy and hardness prediction of AZ91 and AZ9+CNT composites were evaluated by modifying and improving John Mehl-Avrami Semi-Empirical Model. From the analyses, it was found that CNT were homogeneously distributed into the matrix of AZ91 composites due to successfully mechanical alloying using planetary mill. Their densities were 1.98 g/m3 for AZ91 and 1.87 g/m3 for AZ91+ 0.3% CNT. Meanwhile, the compressive strength obtained were 26.8 MPa for AZ91 and 47.1 MPa for AZ91+CNT. The addition of CNT gives softening effect for composite AZ91 + 0.3% CNT and positive effect for composites AZ91 + 0.6% CNT and AZ91 + 0.9% CNT. Composites AZ91 + 0.6% CNT and AZ91 + 0.9% CNT show accelerated ageing and achieve peak aged hardness at 4 hour of ageing time. The positive effect of hardening is expected due to the precipitation of Mg17Al12. The investigation shows the significant of time and temperature are the main role in the precipitation hardening process of the nanocomposite. It is found that the hardness decreases when the temperature is increases and the hardness is increases together with ageing time. Encouraging prediction results are observed when compared with experimental data at a specific time and temperature. Kinetics study show an activation energy of 21kJ/mol of the AZ91 nanocomposite. The purpose of this study is to determine the optimal heat treatment parameter for producing a high-strength AZ91 composite, which is a critical material component for engine blocks used in the automobile sector.
      5  6