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Study the Effect of Polymeric Quenching on Wear Resistance of Eutectic Modified aluminium – Silicon alloy

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Journal of Minerals and Materials Characterization and Engineering 2011年第10期10卷 941-958页

作者： kahtan k. al-khazraji Waleed A. Hanna Osama S. Muhammed Materials Eng. Department University of Technology Baghdad – Iraq.

Polymer quenchants are being used increasingly in the heat treating industry. One reason for this increase is the continual engineering advancements that facilitate their replacement for quench oils and water. The physical properties of a polymer quench bath directly affect the cooling rate of a quenched part. These properties include the type of quenchant, concentration, and agitation. These parameters must be controlled to optimize the quenching process in terms of alloy microstructure, properties, and performance. Such data is scarce for cast aluminum alloys in the literatures and a quantitative measurement of the effects from individual process parameter is not available. In this study a master alloy of modified eutectic (al-12%Si) was prepared and used. The specimens were quenched and heat treated in distilled water, food oil, machine oil and (0.2-1.4) wt% concentrations of polyvinylalcohol (PVA). The specimens are characterized for x-ray diffraction, microstructure, hardness, and wear rate. The results had shown that the use of (0.6) wt% PVA revealed a maximum hardness with a slight decrease in the wear rate, and a maximum decrease in the wear rate was achieved when (1.2) wt % PVA was used compared to the reference cast alloy, also results had revealed that the use of polymer quenchants affect positively well in the decrease in the wear rate of the eutectic al-Si alloy over the traditional quenching media.

关键词： al-Si alloy polymer quenching wear resistance.

A Review and Bibliometric Analysis of the Current Studies for the 6G Network.

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2165-2206页

作者： Qusay M.Salih Md.Arafatur Rahman Ahmad Firdaus Mohammed Rajih Jassim Hasan kahtan Jasni Mohamad Zain Ahmed Hussein ali Faculty of Computing Universiti Malaysia Pahang Al-Sultan Abdullah(UMPSA)PekanPahang26600Malaysia Department of Medical Equipment Technology Engineering Al Salam University CollegeBaghdadIraq School of Mathematics and Computer Science University of WolverhamptonWolverhampton01902UK Department of Production Engineering and Metallurgy University of TechnologyBaghdadIraq Cardiff School of Technologies Cardiff Metropolitan UniversityCardiffCF52YBUK Institute for Big Data Analytics and Artificial Intelligence(IBDAAI) Kompleks Al-KhawarizmiUniversiti Teknologi MARAShah AlamSelangor40450Malaysia Department Computer Science Al-Salam University CollegeBaghdadIraq

The race to develop the next generation of wireless network.,k.own as Sixth Generation(6G)wireless,which will be operational in 2030,has already *** realize its full potential over the next decade,6G will undoubtedly necessitate additional improvements that integrate existing solutions with cutting-edge ***,the studies about 6G are mainly limited and scattered,whereas no bibliometric study covers the 6G ***,this study aims to review,examine,and summarize existing studies and research activities in *** study has examined the Scopus database through a bibliometric analysis of more than 1,000 papers published between 2017 and ***,we applied the bibliometric analysis methods by including(1)document type,(2)subject area,(3)author,and(4)country of *** study’s results reflect the research 6G community’s trends,highlight important research challenges,and elucidate potential directions for future research in this interesting area.

关键词： 6G bibliometric wireless network. review

Sintering Behavior and Microstructure Evolution of Mechanically alloyed W-Bronze Composite Powders by Two-step Ball Milling Process

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Journal of Materials Science & Technology 2013年第1期29卷 59-69页

作者： kahtan S. Mohammed Azmi Rahmat k.airel R. Ahmad School of Materials Engineering Universiti Malaysia Perlis

The miscibility of W in Sn and Cu is extremely poor. Sintering of W-bronze composites to their full density is proved to be difficult. To tack.e this problem, the ball milling process of the W-bronze powder mixture proposed in this study was split into two steps. In the first step, the softness of Sn powder was exploited to modify the surface morphology of W particles. In the second step, Cu was added to the ball milled mixture. To achieve this goal, four 50 wt% W-bronze compact sets of different powder precursors and activator additions were produced. The sintering process was performed at 1150 ℃. The two-step ball milled powder yielded sintered compacts of homogeneous microstructure of fine polygonal W grains dispersed in bronze matrix. They showed the highest hardness and densification levels. The sintered density, microstructure, hardness and densification mechanisms of the sintered compacts were investigated, examined and evaluated using different metallographic, microscopic and measurement facilities.

关键词： Metal matrix composites Mechanical alloying Sintering Microstructure Scanning electron microscopy

Effect of small tool pin profiles on microstructures and mechanical properties of 6061 aluminum alloy by friction stir welding

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Transactions of Nonferrous Metals Society of China 2015年第9期25卷 2856-2865页

作者： H.I.DAWOOD kahtan S.MOHAMMED Azmi RAHMAT M.B.UDAY School of Materials Engineering Universiti Malaysia PerlisTaman Muhibah-Jejawi-Arau Department of Chemical Engineering College of EngineeringUniversity of AL-Qadisiya Centre for Low Carbon Transport in Cooperation with Imperial College London Institute for Vehicle System EngineeringUniversiti Teknologi Malaysia

The effect of small tool pin profiles on the microstructures and mechanical properties of 6061 aluminum alloy joints using friction stir welding （FSW） technique was investigated. Three different tool pin profiles： threaded tapered cylindrical （T1）, triangular （T2） and square （T3） were used to produce the joints. The results indicate that the weld joints are notably affected by joining with different tool pin profiles. The triangular tool pin profile produces thebest metallurgicaland mechanical weld properties compared with other tool pin profiles. Besides, the lowest tensile strength and microhardness are obtained for the joint friction stir welded with square tool pin profile. It is observed that the smaller tool pin profile and shoulder diameter lead to narrow region of heat affected zone （HAZ） and a desired level of softening. The fracture surface examination shows that the joints are also affected when welding with different types of tool pin profiles. The fracture surface shows that the triangular specimen fails with a ductile fracture mode during the tensile test, while the brittle fracture modes are observed in the joints fabricated with other tool pin profiles （T1 and T3）.

关键词： friction stir welding small tool pin profile mechanical properties aluminum alloy grain size

Microstructural Evaluation and Mechanical Properties of an al-Zn-Mg-Cu-alloy after Addition of Nick.l under RRA Conditions

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Materials Sciences and Applications 2013年第11期4卷 704-711页

作者： Haider T. Naeem kahtan S. Mohammed School of Materials Engineering University Malaysia Perils Taman Muhibbah Perlis Malaysia School of Materials Engineering University Malaysia Perils Taman Muhibbah Perlis Malaysia College of Engineering Al- Muthana University Al-Muthana Iraq

The effects of nick.l in improving the mechanical properties and microstructural of al-Zn-Mg-Cu alloys produced by semi-direct chill casting were investigated. aluminium alloys were homogenized at different temperatures conditions, which aged at 120°C for 24 h (T6 temper), and retrogressed at 180°C for 30 min and then re-aged at 120°C for 24 h (RRA). The results of the microstructural analyses showed that with adding nick.l to aluminium alloy, nick.l-rich dispersoid particles were formed, such as al7Cu4Ni, al4Ni3, al75Ni10Fe15, al3Ni2, and al50Mg48Ni7. Intermetallics compounds within the matrix alloy led to dispersion and fine-grain mechanisms which prevent the recrystallization and grain growth. Enhancement of mechanical properties of the alloys study is obtained through the precipitation hardening of alloying elements of the base alloy besides Ni-bearing dispersoid particles. The microstructure of these alloys were examined through optical and scanning electron microscopy along with energy dispersive X-ray and X-ray diffraction.

关键词： al-Zn-Mg-Cu alloys Intermetallic Microstructure Mechanical Orowan Mechanism

On Certain Theta Function Identities Analogous to Ramanujan’s <i>P-Q</i>Eta Function Identities

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Applied Mathematics 2011年第7期2卷 874-882页

作者： k.liyur R. Vasuk. Abdulrawf Abdulrahman Abdullah kahtan 不详

The purpose of this paper is to provide direct proofs of certain theta function identities analogous to Ramanujan’s P-Q eta functions identities.

关键词： Eta Function Identities Theta Function P-Q Modular Equations

Synthesis and Densification of Tungsten-Brass Composite by Mechanical alloying

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Open Journal of Metal 2015年第3期5卷 27-36页

作者： kahtan S. Mohammed Baba Gowon Shamsul Baharin Bin Jamaluddin Zuhailawati Hussain Polycarp Evarastics School of Materials Engineering Universiti Malaysia Perlis (UniMAP) D/A Pajabat Pos Besar Kangar Malaysia Department of Metallurgical and Materials Engineering Federal Polytechnic Idah Nigeria School of Materials and Mineral Resources Engineering Engineering Campus Universiti Sains Malaysia Nibong Tebal Malaysia

Fabrication of full-density W-brass composites is very difficult to achieve because of evaporation of zinc, insolubility of W and brass and compacts expansion. In this study, to achieve full-density W-brass composites, mechanical alloying (MA) and activated sintering process were utilized. Mechanical coating of W with Ni using high energy planetary ball mill was carried out. The milling was divided into two stages: to alloy and modify the surface of W with Ni for enhanced activation. The microstructure of the milled powders and sintered compacts, elemental composition and phases present were studied by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) respectively. As-received powder compacts was also sintered under the same condition for comparison purpose. The effects of milling time on the microstructure, sinterability and the hardness of the composites were investigated. It was observed that the samples produced from 8 h milled powder had the highest relative sintered density (98% TD) and microhardness (234 Hv). On the other hand, the samples from the as-received powders expanded and had a relative sintered density of (67% TD) and microhardness as low as 24 Hv. The significance of this study is the possibility of producing W-brass composites as a cheaper alternative to W-Cu composites.

关键词： W-Brass Mechanical alloying Microstructure Expansion Hardness

The Effects of Sintering Temperature on the Densification of Mechanically alloyed W-Brass Composites

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Open Journal of Metal 2015年第3期5卷 19-26页

作者： Baba Gowon kahtan S. Mohammed Shamsul Baharin Bin Jamaluddin Zuhailawati Hussain Polycarp Evarastics School of Materials Engineering Universiti Malaysia Perlis (UniMAP) D/A Pajabat Pos Besar Kangar Malaysia Department of Metallurgical and Materials Engineering Federal Polytechnic Idah Nigeria School of Materials and Mineral Resources Engineering Engineering Campus Universiti Sains Malaysia Nibong Tebal Malaysia

Prealloyed (PA) and premixed (PM) W-brass with the composition of 60 wt% W, 1 wt% Ni and 39 wt% brass was sintered at the temperature of 800°C, 920°C and 1000°C each. As a result of difficulties in the densification of W-Cu and W-Cu alloys, mechanical alloying (MA) and activated sintering were combined. The powders were mechanically alloyed for 13 hours to produce nanosized W grains embedded in brass. The microstructure and properties of these composites with increase in sintering temperature has been studied. Both prealloyed and premixed composites sintered at 800°C (solid state sintering) and 920°C (sub-solidus state sintering) have lower sintered densities and hardness. The densification rate in the premixed composites was observed to be higher than that of the prealloyed composites. Their densification and properties increased with the increase in the sintering temperature. Premixed composite sintered at 1000°C had 91.0% sintered density, 180 Hv microhardness against 76.0% and 133 Hv respectively for prealloyed composite at the same temperature. The values of electrical conductivity in both prealloyed and premixed composites increased with increase in temperature.

关键词： W-Brass Temperature Densification Prealloy Hardness