Browsing by Author "Chattopadhyaya, Somnath"

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    Deposition of Steel over Steel by Friction Surfacing Technique and Investigation of its Physical Geometry
    (Research and Development Wing, MIST, 2023-12) Jangid, Hemlata; Singh, Nirmal K.; Chattopadhyaya, Somnath; Krishna Sai, M. Mohan; Parmar, Gaurav
    Friction surfacing (FS) is a coating technique inspired by friction stir welding. FS is a solid-state, thermo-mechanical process providing excellent wear and corrosion resistance properties. Frictional heating elevates the temperature of the consumable rotating tool (mechtrode) up to the softening of the material, the tool is traversed along the length of the plate, and the material gets deposited onto the substrate plate with good mechanical properties and excellent corrosion resistance properties, FS process may have wider application in the mining industry to provide an adequate coating on excavator's teeth, shovel teeth, and dragline teeth. This paper has an experimental approach to investigate the coating integrity during the FSed deposition of AISI4140 (consumable rod) over EN24 plate on a conventional milling machine. Various testslike wear test, XRD analysis, hardness, IR thermography, surface roughness, FESEM images have been analysed. Experiments have shown that at a low travel speed of 16mm/min, the coating is non-uniform and an excessive increase in travel speed will not give proper time for softening of the material, resulting in a discontinuous coating so the optimum travel speed must be chosen for better quality coating. Also, one more approach has been made to explore the effect of mechtrode shapes on the flash formation of the consumable tool while deposition of mild steel over mild steel on the milling machine where conical cylinder tool shape wasmore efficiently worked.
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    Development of Space-Borne Antenna Reflector via 3D Printing
    (Research and Development Wing, MIST, 2023-12) Kori, Jaya; Patnaik, Sampurna; Chattopadhyaya, Somnath; Chatternjee, Sayan
    The growing necessity of large aperture-based structures for many aerospace applications emphasizes the need to deploy large antenna structures in space. The space antennas should be light in weight and have low stowage volume, with efficient membrane packaging. The concept of additive manufacturing has been introduced to reduce weight as well as cost. In this paper, a comparative study has been done to analyze the advancement made in reducingweight with adequate strength. Based on the study, the main objectives are to develop a 3D-printed spherical reflector model with high specific strength and to assess the consistency of the model's shape. For determining the specific strength, tensile testing is performed on four different infill densities (20%, 40%, 60%, and 80%) with a grid infill pattern. It was observed that the specimen with 80% infill density has the highest tensile strength, 36.56 MPa, which is 23.51% more than 20% infill. However,the specimen with 20% infill density has the highest specific strength of 19.323 GPa/kg among the four specimens, which is approximately 64.64% higher than the 100% infill density. As a result of the testing, the spherical reflector model is 3D printed with 20% infill density, and it was found that the model achieves its shape stability and shape consistency with adequate specific strength.