Papers by Keyword: Powder Metallurgy

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Authors: Imran Hamid, Abdul Rauf, Faisal Nasim, Muhammad Siddique, Adnan Gul
Abstract: Composites are the combination of materials that are mixed together to achieve specific structural properties. Teflon (Polytetrafluoroethylene PTFE) consists of long-chain molecular structure. Its monomer consists of two carbon atoms each of them having flourine atoms attached. Bonds within each chain are strong covalent bonds where as the secondary bonds between two chains are weaker. By raising temperature, the distance between the chains increases providing good adjustment of the atoms of other materials due to anisotropy of its mechanical properties. Powder metallurgy technique using hot isostatic pressing, a hybrid densification process in which pressure and temperature are applied at the same time, has been used to develop a teflon-copper composite material. Three samples were prepared by changing the teflon-copper composition as 60:40%, 65:35% and 70:30% by weight. Commercially available powders of teflon and copper of grain size ~ 40 μm was used. The aim to develop this type of material was to increase its density (~ 4 g/cm3), and hardness. The commercial applications of such type of composite material are solid lubricants, sleeves, bearings etc. In this paper the effect of composition on hardness, tensile strength and surface roughness is studied.
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Authors: Syeda Ammara Batool, Akhlaq Ahmad, Abdul Wadood, Abdul Mateen, Syed Wilayat Hussain
Abstract: Aluminum (Al) and Titanium (Ti) based lightweight alloys have been a topic of discussion and research for a few decades now. Resulting alloys with hard intermetallic phases in Al-Ti binary system have good microstructural and mechanical properties including low densities, high specific strength, better resistance against oxidation and corrosion which are highly desirable in aerospace industry. Such an alloy system was studied in our research. Powder metallurgy (PM) was used as processing route because of its economical and easy operation. Samples were prepared using metallic powders of Aluminum (Al) and Titanium (Ti) with varying compositions of 95 at.% Al-Ti, 90 at.% Al-Ti and 88 at.% Al-10 at.% Ti-2 at.% SiC. After compaction, pressureless sintering was carried out at 620°C for several hours in Argon atmosphere followed by annealing resulting in a reasonably dense Al-Ti alloy. Microstructure and phase composition of alloy was analyzed by Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS), respectively. Hardness was evaluated by Vickers micro indentation test. An increase in hardness was observed. Sample containing reinforcement particles (SiC) demonstrated highest value of hardness.
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Authors: Karim Arar, Salah Mansouri, Rachid Benbouta, Kamel Fedaoui
Abstract: In the present work, (Cu-Sn, Cu-Co) based alloys with different compositions have been obtained by using powder metallurgy (PM). These alloys were created with the purpose of increasing mechanical and structural properties of the industrial parts. The compacts are made according to the sintering manufacturing method, the uniaxial compressed cold samples. Metallographic characterizations, hardness and density measurements were carried out in order to study the influence of the addition of tin and cobalt, the variation of the compaction pressure and the sintering temperature on the finishing product. It has been proved that the addition of tin and cobalt to a copper powder mixture increase the properties of the sintered parts.
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Authors: C.D. Zuraidawani, F.W. Norhadira, Mochd Nazree B. Derman
Abstract: The Mg-1wt.%Ca alloy was fabricated using powder metallurgy method. The anodizing process were done by using different voltage (5V, 15V, 25V) and concentration of KOH (0.1M, 0.5M, 1.0M). The surface changes on PM Mg/1wt.%Ca resulted by anodizing was analyzed using SEM-EDX and XRD pattern. Meanwhile, surface hardness was measured by micro-Vickers hardness machine. The experiment found different XRD pattern between all non-anodized and anodized samples. The study found that increasing the voltage will increase the hardness while increasing KOH concentration reduced the hardness. The relation of the hardness and oxide film formation can be analyzed using SEM-EDX and XRD pattern. The optimum value for voltage, KOH concentration and hardness are 25V, 0.1M and 27.2 HV. The XRD detect the changes in PM Mg/1wt.% Ca indicates the oxide film formation.
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Authors: Achanai Buasri, Chudeth Prasanwon, Bhornwalan Boonsong, Pantira Kohprasert, Vorrada Loryuenyong
Abstract: This research studied the fabrication of graphene-reinforced aluminum composite via powder metallurgy and uniaxial pressing. The process started from mixing graphene with aluminum powder with various content of graphene (0.5, 1, 1.5, 2 and 4 wt.%) in acetone medium, followed by dispersion process at high frequency using an ultrasonic bath. The mixed composite powders were then formed into pellet and sintered at 600°C. The results showed that when graphene content in graphene reinforced aluminum composite is low (0.5wt.%, 1wt.% and 1.5wt.%), the hardness was enhanced. It was suspected that graphene could get into aluminum matrix and impede the grain growth of aluminum and dislocation movement. However, when excessive graphene content was added, graphene nanoplatelets tended to agglomerate, decreasing the hardness of composite. Similarly, the improvement of electrical and thermal conductivities was achieved with a low content of graphene. The well dispersion of graphene in aluminum matrix could facilitate the electron transport and to induce the pore reduction throughout the matrix.
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