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Mechanical properties of stabilized zirconia nanocrystalline EB-PVD coating evaluated by micro and nano indentation

Journal of Advanced Ceramics 2013年第4期2卷 333-340页

作者： Meysam KESHAVARZ mohd hasbullah idris Norhayati AHMAD Department of Materials Science and Engineering Faculty of Mechanical EngineeringUniversiti Teknologi Malaysia81310 UTM Johor BahruJohorMalaysia

Yttria-stabilized zirconia(YSZ)thin nanocrystalline coatings at different substrate preheating temperatures were deposited via electron beam-physical vapour deposition(EB-PVD).Nanocrystalline ZrO_(2)-Y_(2)O_(3) was deposited on the bond coat in order to compensate for the coefficient of thermal expansion(CTE),which can be functionalized as a thermal barrier coating(TBC).The aim of this study was to evaluate mechanical properties with respect to adhesion of zirconia nanocrystalline’s top ceramic layer to the interfacial bond coat by utilizing micro and nano indentation *** the present paper,the structural studies were carried out using X-ray diffraction(XRD)analysis of coating content(8 mol%of Y_(2)O_(3)).The tetragonal phase of stabilized zirconia was *** emission scanning electron microscopy(FESEM)and atomic force microscopy(AFM)were employed to characterize the coatings’morphology and *** mechanical behavior of ZrO_(2)-Y_(2)O_(3) thin films under point loading conditions was studied by nanoindentation using a Berkovich indenter with 130 nm tip ***,adhesion of top coat to the interfacial underlying metallic bond coat known as MCrAlY(M=Ni,Co)was estimated according to the highest peak load tests;for a 120 mN peak load,the film manifested tolerable adhesion ***,nanoindentation of ZrO_(2)-Y_(2)O_(3) nanostructure deposited at 1050℃substrate preheating temperature produced the highest hardness value of about 21.7 *** micro hardness was utilized with the aid of the Tabor equation in order to achieve deeper insight into the correlation between adhesion and deposition process parameters.

关键词： zirconia nanoindentation nanocrystalline electron beam-physical vapour deposition(EB-PVD) thermal barrier coating(TBC)

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Effect of Primary and Eutectic Mg_2Si Crystal Modifications on the Mechanical Properties and Sliding Wear Behaviour of an Al–20Mg_2Si–2Cu–xBi Composite

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Journal of Materials Science & Technology 2016年第11期32卷 1083-1097页

作者： Saeed Farahany Hamidreza Ghandvar Nur Azmah Nordin Ali Ourdjini mohd hasbullah idris Department of Materials and Mechanical Engineering Buein Zahra Technical University Department of Materials Manufacturing and Industrial Engineering Faculty of Mechanical Engineering Universiti Teknologi Malaysia (UTM) Department of Mechanical Engineering Faculty of Engineering University of Ottawa

This work investigated the microstructure evolution, tensile, impact, hardness, and sliding wear properties of an Al–20Mg2Si–2Cu in situ composite treated with different Bi contents. The desired modification of primary Mg2 Si particles was achieved with the addition of 0.4 wt% Bi. Increasing Bi beyond 0.4 wt%resulted in a loss of modification, possibly due to the formation of Al8 MgB iS i4 compound before the precipitation of the primary Mg2 Si. Additionally, the structure of the pseudo-eutectic Mg2 Si was transformed from plate to fibrous, which was consistent with decrease of growth temperature extracted from the cooling curve thermal analysis. Addition of Bi had an effect on the morphology of Al5 Fe Si（β）, Al2Cu（θ） and Al5Cu2Mg8Si6（Q） intermetallic compounds. The tensile strength, elongation percentage, impact toughness, and hardness increased by 6%, 13%, 75%, and 23%, respectively, due to modification of both the primary and eutectic Mg2 Si crystals. The tensile and impact fracture surfaces showed fewer decohered particles in the Bi-treated composite. The enhancement in wear resistance of the Bi-treated composite could be attributed to solid lubricant function of insoluble soft Bi phase and modification effects on Mg2 Si particles.

关键词： Al–Mg2Si Composite Modification Bismuth Mechanical properties Wear

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Influence of Gating System,Sand Grain Size,and Mould Coating on Microstructure and Mechanical Properties of Thin-Wall Ductile Iron

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Journal of Iron and Steel Research International 2010年第12期17卷 38-45页

作者： Hassan Jafari mohd hasbullah idris Ali Ourdjini Majid Karimian Gholamhassan Payganeh Department of Materials Engineering Universiti Teknologi Malaysia Department of Materials Engineering Shahid Rajaee Teacher Training University

Two gating systems namely stepped and tapered runners were used to cast strip samples with different thicknesses by CO2/silicate process using sand grain sizes of AFS 151 and 171. To assess the effect of mould coating on the properties of thin wall ductile iron, half of the moulds were coated whilst the rest were not coated. Molten metal with the carbon equivalent of 4.29% was prepared and poured at 1 450 ℃. Microstructure of the specimens was analyzed by optical and scanning electron microscopes. Count, area fraction, roundness and diameter of the graphite nodules of the samples were measured by image analyzer. Brinell hardness and tensile tests of all the samples were also conducted. The results show that by using stepped runner gating system with uncoated and coarse sand mould, roundness and count of the graphite nodules decrease whereas diameter and area fraction increase. Although fine sand and coated mould cause longer distance of molten metal travel, hardness and strength of the samples decrease.

关键词： thin-wail ductile iron gating system sand grain size mould coating mechanical property mierostructure

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Effect of Multi-Step Tempering on Retained Austenite and Mechanical Properties of Low Alloy Steel

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Journal of Iron and Steel Research International 2011年第12期18卷 49-56页

作者： Hamid Reza Bakhsheshi-Rad Ahmad Monshi Hossain Monajatizadeh mohd hasbullah idris Mohammed Rafiq Abdul Kadir Hassan Jafari Materials Engineering Department Islamic Azad University Materials Engineering Department Faculty of Mechanical EngineeringUniversity Technology Malaysia Materials Engineering Department Faculty of Mechanical EngineeringShahid Rajaee Teacher Training University

The effect of multi-step tempering on retained austenite content and mechanical properties of low alloy steel used in the forged cold back-up roll was *** evolutions were characterized by optical microscope,X-ray diffraction,scanning electron microscope and Feritscope,while the mechanical properties were determined by hardness and tensile *** results revealed that the content of retained austenite decreased by about 2% after multi-step ***,the content of retained austenite increased from 3.6% to 5.1% by increasing multi-step tempering *** hardness and tensile strength increased as the austenitization temperature changed from 800 to 920 ℃,while above 920 ℃,hardness and tensile strength *** addition,the maximum values of hardness,ultimate and yield strength were obtained via triple tempering at 520 ℃,while beyond 520 ℃,the hardness,ultimate and yield strength decreased sharply.

关键词： cold back-up roll retained austenite mechanical property austenite grain size

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Effect of pattern coating thickness on characteristics of lost foam Al-Si-Cu alloy casting

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Transactions of Nonferrous Metals Society of China 2012年第9期22卷 2092-2097页

作者： Majid KARIMIAN Ali OURDJINI mohd hasbullah idris Hassan JAFARI Department of Mechanical Engineering Islamic Azad University of Komeyni Shahr Esfahan 119-84175 Iran Department of Materials Engineering Faculty of Mechanical Engineering Universiti Teknologi Malaysia 81310 UTM Skudai Johor Malaysia Department of Materials Engineering Faculty of Mechanical Engineering Shahid Rajaee Teacher Training University Tehran 16785-136 Iran

An experimental study on lost foam casting of an Al-Si-Cu alloy was conducted. The main objective was to study the effect of pattern coating thickness on casting imperfection and porosity percentage as well as eutectic silicon spacing of the alloy. The results showed that increasing slurry viscosity and flask dipping time influenced the casting integrity and microstructural characteristics. It was found that thinner pattern coating produced improved mould filling, refined microstructure and higher quality castings containing less porosity.

关键词： aluminum alloy lost foam casting coating thickness slurry viscosity dipping time porosity

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Effect of solution treatment on corrosion characteristics of biodegradable Mg-6Zn alloy

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Transactions of Nonferrous Metals Society of China 2015年第5期25卷 1490-1499页

作者： Seyed Morteza Ghaffari SHAHRI mohd hasbullah idris Hassan JAFARI Babak GHOLAMPOUR Mahtab ASSADIAN Department of Materials Manufacturing and Industrial Engineering Faculty of Mechanical EngineeringUniversiti Teknologi Malaysia Department of Materials Engineering Faculty of Mechanical EngineeringShahid Rajaee Teacher Training University

A binary Mg-6Zn biodegradable alloy was solution treated to evaluate the effects of resulting microstructure changes on the alloy＇s degradation rate and mechanisms in-vitro. The treatment was conducted at 350 °C for 6-48 h. Optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction were used to analyze the as-cast and treated samples. Immersion and electrochemical tests were performed in simulated body fluid at 37 °C to assess the samples corrosion resistance. To confirm the results of the corrosion tests, p H measurement was carried out. It is found that over 24 h solution treatment dissolves intermetallic phases in matrix and produces an almost single phase microstructure. Decreasing the intermetallic phases results in lower cathode/anode region ratios and lowers corrosion rates. The results of the electrochemical and mass loss tests reveal that extended solution treatment improves the corrosion resistance of the alloy. The results also show that solution at 350 °C for 24 h enhances the corrosion resistance of the as-cast alloy more than 60%. In addition, decreasing intermetallic phases in the microstructure accompanied a lower p H rise reduced corrosion rate. Solution treatment is suggested as a corrosion improving process for the application of Mg-Zn alloys as biodegradable implant materials.

关键词： magnesium alloy solution treatment biodegradation immersion polarization orthopaedic implant

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Effect of fluoride treatment on corrosion behavior of Mg-Ca binary alloy for implant application

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Transactions of Nonferrous Metals Society of China 2013年第3期23卷 699-710页

作者： Hamid Reza Bakhsheshi-Rad mohd hasbullah idris Moha mmed Rafiq Abdul Kadir Mohammadreza Daroonparvar Materials Engineering Department Faculty of Mechanical EngineeringUniversiti Teknologi MalaysiaSkudai 81310JohorMalaysia Department of Biomechanics & Biomedical Materials Faculty of Biomedical Engineering & Health SciencesUniversiti Teknologi MalaysiaSk udai 81310JohorMalaysia

The influence of hydrofluoric acid（HF） treatment on the corrosion behavior of the Mg-0.5Ca alloys was investigated by immersion specimen in sodium hydroxide and HF solutions with various concentrations and durations at room *** evolutions of the specimens were characterized by atomic force microscopy,X-ray diffraction,field-emission scanning electron *** corrosion resistance was examined through potentiodynamic polarization and immersion test in Kokubo *** results revealed that the fluoride treated Mg-0.5Ca alloys produced by immersion in 40% HF provided more uniform,dense and thicker coating layer（12.6 μm） compared with the 35% HF treated *** electrochemical test showed that the corrosion resistance of fluoride treated specimen was 35 times higher compared with the untreated Mg-0.5Ca alloy specimen in Kokubo *** vitro degradation rate of the fluoride treated specimens was much lower than untreated Mg-0.5Ca alloy in Kokubo *** immersion test the surface of 40% HF treated sample showed a few corrosion dots,while untreated specimens were fully covered by corrosion products and *** treated Mg-0.5Ca alloy with 40% HF is a promising candidate as biodegradable implants due to its low degradation kinetics and good biocompatibility.

关键词： Mg-Ca alloy surface treatment corrosion behavior biocompatibility

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Zinc-doped hydroxyapatite-zeolite/polycaprolactone composites coating on magnesium substrate for enhancing in-vitro corrosion and antibacterial performance

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Transactions of Nonferrous Metals Society of China 2020年第1期30卷 123-133页

作者： Nida IQBAL Saman IQBAL Tanveer IQBAL H.R.BAKHSHESHI-RAD Ahmed ALSAKKAF Ahmad KAMIL Mohammed Rafiq ABDUL KADIR mohd hasbullah idris H.Balaji RAGHAV Biomedical Engineering Centre University of Engineering and TechnologyKala Shah Kaku(KSK)CampusLahorePakistan Department of Physics University of the PunjabQuaid-e-Azam CampusLaborePakistan Department of Chemical Polymer&Composite Material Engineering University of Engineering and TechnologyKala Shah Kaku(KSK)New CampusLahorePakistan Advanced Materials Research Center Department of Materials EngineeringNajafabad BranchIslamic Azad UniversityNajafabadIran School of Mechanical Engineering Faculty of EngineeringUniversiti Teknologi MalaysiaJohorMalaysia Kulliyyah of Science International Islamic University MalaysiaBandar Indera Mahkota CampusJalan Sultan Ahmad Shah25200 KuantanPahang Darul MakmurMalaysia School of Biomedical Engineering and Health Sciences Faculty of EngineeringUniversiti Teknologi MalaysiaJohorMalaysia Tissue Engineering Group(TEG) National Orthopaedic Centre of Excellence in Research and Learning(NOCERAL)Department of Orthopaedic SurgeryFaculty of MedicineUniversity of Malaya50603 Lembah PantaiKuala LumpurMalaysia

This work is focused on developing zinc-doped hydroxyapatite-zeolite(Zn HA-Zeo)and polycaprolactone(PCL)composite coatings on magnesium(Mg)substrate to improve the corrosion resistance and antimicrobial ***-coating technique was used to coat Zn HA-Zeo/PCL on the Mg substrate at room *** samples were subjected to field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),Fourier transform infrared(FTIR),energy dispersive X-ray spectroscopy(EDX)and antimicrobial *** demonstrated that composite coatings consist of HA,scholzite,zeolite,and PCL *** spectra indicated the presence of calcium(Ca),silicon(Si),aluminum(Al),zinc(Zn),phosphorus(P)and oxygen(O).The composite surface appeared in spherical-like microstructure on coating with thickness ranging 226-260μ***-doped HA-Zeo composite coating had a high corrosion resistance and provided sufficient protection to the Mg surface against galvanic *** Zn HA-Zeo coating samples exhibited superior disc inhibition by confirming antimicrobial activity against the *** as compared to HA-Zeo *** these results showed that the Zn HA-Zeo coatings not only improved the corrosion resistance,but also enhanced the antimicrobial property and hence they can be used as suitable candidates for implant applications.

关键词： biodegradable magnesium bioceramics coating corrosion resistance antimicrobial activity

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DNBP-CCA:A Novel Approach to Enhancing Heterogeneous Data Traffic and Reliable Data Transmission for Body Area Network

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Computers, Materials & Continua 2024年第5期79卷 2851-2878页

作者： Abdulwadood Alawadhi mohd.hasbullah Omar Abdullah Almogahed Noradila Nordin Salman A.Alqahtani Atif M.Alamri InterNetWorks Research Laboratory School of ComputingUniversiti Utara MalaysiaSintok06010Malaysia Faculty of Computer Science and Information Technology Universiti Tun Hussein Onn MalaysiaParit RajaJohor86400Malaysia School of Games&Creative Technology University for the Creative ArtsFarnhamGU97DSUK Computer Engineering Department College of Computer and Information SciencesKing Saud UniversityRiyadh11543Saudi Arabia Software Engineering Department College of Computer and Information SciencesKing Saud UniversityRiyadh11543Saudi Arabia

The increased adoption of Internet of Medical Things (IoMT) technologies has resulted in the widespread use ofBody Area Networks (BANs) in medical and non-medical domains. However, the performance of IEEE 802.15.4-based BANs is impacted by challenges related to heterogeneous data traffic requirements among nodes, includingcontention during finite backoff periods, association delays, and traffic channel access through clear channelassessment (CCA) algorithms. These challenges lead to increased packet collisions, queuing delays, retransmissions,and the neglect of critical traffic, thereby hindering performance indicators such as throughput, packet deliveryratio, packet drop rate, and packet delay. Therefore, we propose Dynamic Next Backoff Period and Clear ChannelAssessment (DNBP-CCA) schemes to address these issues. The DNBP-CCA schemes leverage a combination ofthe Dynamic Next Backoff Period (DNBP) scheme and the Dynamic Next Clear Channel Assessment (DNCCA)scheme. The DNBP scheme employs a fuzzy Takagi, Sugeno, and Kang (TSK) model’s inference system toquantitatively analyze backoff exponent, channel clearance, collision ratio, and data rate as input parameters. Onthe other hand, the DNCCA scheme dynamically adapts the CCA process based on requested data transmission tothe coordinator, considering input parameters such as buffer status ratio and acknowledgement ratio. As a result,simulations demonstrate that our proposed schemes are better than some existing representative approaches andenhance data transmission, reduce node collisions, improve average throughput, and packet delivery ratio, anddecrease average packet drop rate and packet delay.

关键词： Internet of Medical Things body area networks backoff period tsk fuzzy model clear channel assessment media access control

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Adaptable and Dynamic Access Control Decision-Enforcement Approach Based on Multilayer Hybrid Deep Learning Techniques in BYOD Environment

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Computers, Materials & Continua 2024年第9期80卷 4663-4686页

作者： Aljuaid Turkea Ayedh M Ainuddin Wahid Abdul Wahab mohd Yamani Idna idris Faculty of Computer Science and Information Technology Universiti MalayaKuala Lumpur50603Malaysia Faculty of Computer Science and Information Technology Shaqra UniversityShaqra11961Saudi Arabia Center for Mobile Cloud Computing Faculty of Computer Science and Information TechnologyUniversiti MalayaKuala Lumpur50603Malaysia

Organizations are adopting the Bring Your Own Device(BYOD)concept to enhance productivity and reduce ***,this trend introduces security challenges,such as unauthorized *** access control systems,such as Attribute-Based Access Control(ABAC)and Role-Based Access Control(RBAC),are limited in their ability to enforce access decisions due to the variability and dynamism of attributes related to users and *** paper proposes a method for enforcing access decisions that is adaptable and dynamic,based on multilayer hybrid deep learning techniques,particularly the Tabular Deep Neural Network Tabular DNN *** technique transforms all input attributes in an access request into a binary classification(allow or deny)using multiple layers,ensuring accurate and efficient access *** proposed solution was evaluated using the Kaggle Amazon access control policy dataset and demonstrated its effectiveness by achieving a 94%accuracy ***,the proposed solution enhances the implementation of access decisions based on a variety of resource and user attributes while ensuring privacy through indirect communication with the Policy Administration Point(PAP).This solution significantly improves the flexibility of access control systems,making themmore dynamic and adaptable to the evolving needs ofmodern ***,it offers a scalable approach to manage the complexities associated with the BYOD environment,providing a robust framework for secure and efficient access management.

关键词： BYOD security access control access control decision-enforcement deep learning neural network techniques TabularDNN multilayer dynamic adaptable flexibility bottlenecks performance policy conflict

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