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Structural and mechanical properties of friction stir welded Al2O3 and SiC reinforced Al 7075 alloys
Jarair Shafique,Hussein Alrobei,Aneela Wakeel,Rizwan Ahmed Malik,Azhar Hussain,Jaehwan Kim,무하마드 라티프 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4
Al 7075 of 4 mm thickness plates were welded by using ceramic particles of micron size. Different revolution speed, ranging from 1600 to 2000 RPM and transverse speed of 17 to 35 mm/min were applied. The sound weld is achieved at revolution speed of 1600 RPM and transverse speed of 17 mm/min. In this work, ceramic particles of Al 2 O 3 and SiC were used to reduce the effect of the heat towards the base material during friction stir welding owing to their high friction coefficient and reasonable thermal conductivity and to enhance mechanical properties. Vickers microhardness test was performed on the plain, Al 2 O 3 , and SiC mixed Al 7075 welded samples. This test showed the welded joint by using Al 2 O 3 and SiC have 10 to 12 % increase in hardness than that of the joint without using particles. Tensile strength of welded joints without ceramics particles showed improved results. Dispersion of ceramics particles was examined by metallurgical microscope. Scanning electron microscope (SEM) images and fracture analysis of the stir welded zone and base materials were observed. The structuralproperty relationship of plain, Al 2 O 3 , and SiC mixed Al 7075 welded samples was discussed systematically and found that improvement in hardness for Al 2 O 3 , and SiC mixed Al 7075 welded samples was due to the higher thermal conductivities of added ceramic particles and precipitation strengthening mechanism. While, reduction in tensile strength ascribed to the formation of intermetallic compounds.
Zahoor Ahmad,Muhammad Aziz Choudhary,Aneela Mehmood,Riffat Wakeel,Tashfeen Akhtar,Muhammad Aftab Rafiq 한국고분자학회 2016 Macromolecular Research Vol.24 No.7
Polypyrrole (ppy) has been synthesized by employing [Co(NH3)6]Cl3 as a new oxidizing agent under basic condition in aquous solution. The optimized ratio of monomer to oxidizing agent has been taken as 1:2. The reaction was allowed to continue for 24-48 h at room temperature. The as synthesized ppy displayed well defined morphology, which was seemed as time dependent. It was nanospheres at 24 h, micro/nano mixture at 36 h and microspheres and microfibers at 48 h. The FTIR confirmed the formation of ppy due to the presence of characteristics broader ring and N-H stretching vibrations. The XRD showed the development of crystallites only within the fibrous ppy. The thermal and structural correlation was determined using TGA and DSC techniques alongwith SEM. The polymer was found to be considerably more stable as compared with similarly synthesized using other such oxidants. The conductivity of pure polymer and effect of NH3 over its conductivity was analyzed by four probe technique. Its strong potential of NH3 sensing has been confirmed from this technique due to showing linear increase in its conductivity. These results demonstrated that cobalt(III) is a potential oxidizing agent to produce thermally stable nano/microspheres of ppy. Moreover, the material was found quite useful for its characteristics of NH3 sensing that can be applied for other nitrogenous bases.