Advanced Materials Processing Research Group
Institution: Indian Institute of Technology Gandhinagar
About the lab
Advanced Materials Processing Research Group (AMPRG) primarily works on FSWP and (FSC); surface composites, modelling and simulation of various welding and joining processes. The group also work in deep learning (artificial intelligence) and additive manufacturing (3D printing). The research involved processing and characterization of metallic (aluminum, copper, titanium, steel, magnesium alloys), polymers and ceramic materials. We strive to support the needs of aerospace, automobile, marine, defense and strategic sectors. In FSW, the group has capability to predict heat transfer, material flow, tool wear, grain evolution, recrystallization, thermal and strain gradients.
Featured projects (1)
Featured research (9)
Low-density polyethylene (LDPE) is a soft thermoplastic with extensive application as a packing material such as plastic bags, dispensing bottles, milk pouches, etc. Many LDPE bags are used and dumped in landfills every year, leading to millions of tons of persistent waste. In addition, the recycling of LDPE is of no commercial interest due to its low stiffness, poor mechanical properties, and limited commercial application. In the current work, we attempt to recycle milk pouches made of LDPE to create polymer filaments for fused deposition modeling (FDM), thereby adding value to waste plastic by converting it into high-value 3D printer filament. This research examines the feasibility of reclamation of waste LDPE milk pouches as filament for 3D printers and studies the changes in filament’s chemical and mechanical properties when produced at different temperatures. The waste milk pouches are cleaned thoroughly, shredded, and extruded using a single screw extruder at three nozzle temperatures, i.e., 150°C, 180°C, 210°C. The extruded specimens are analyzed using an optical microscope and scanning electron microscope (SEM) for surface texture. The effect of change in process temperature on flow behaviors is also studied by integrating a current sensor and an encoder. Fourier transform infrared spectroscopy (FTIR) analysis is performed on the filaments and the used LDPE milk pouches to compare the chemical bondings of the polymer. The mechanical properties of the extruded filaments are examined using dynamic mechanical analysis (DMA). The morphological analysis, chemical characterization, and mechanical characterization of prepared filaments are presented. The results show that the chemical bondings are intact after extrusion at all the temperatures examined in this work. The surface texture and the mechanical properties are better at higher temperatures owing to better fluidity and are more suitable for fused deposition modeling. Thus, it is possible to valorize waste LDPE milk pouches by transforming them into filaments for 3D printing.
Electron Beam Melting (EBM) is an emerging additive manufacturing technique for the fabrication of titanium alloy Ti-6Al-4V for orthopedic applications. Here, a hybrid manufacturing technique viz. EBM with Friction Stir Processing (FSP) has been proposed to enhance implant surface properties. The surface modification using FSP reduces the roughness generated by the EBM technique from ~44.77 μm to ~15.82 μm. Simultaneously, FSP improves the biological and mechanical properties of the Ti-6Al-4V substrates. The roughness, wettability, amounts of ions released, and surface microhardness were measured to analyze the stability of the substrates. The effect of the hybrid processing strategy on cell viability was tested against mouse fibroblast cells NIH3T3 through MTT assay, and we found that the friction stir processed substrate (EBM-F) showed the highest cell viability. The EBM-F surface displays a two-fold increase in the cell-viability as compared to the unprocessed EBM surface after 24 h of cell-seeding. The FSP substrate allows human cervical cells HeLa to adhere onto its surface while selectively preventing the attachment of E.coli bacterial cells. These observations towards cells signify biocompatible surface characteristics of the FSP EBM substrate.
There have been claims of early use of high-carbon steel in South India. Still, the antiquity, elemental composition and steelmaking process have not been explored adequately. The high carbon steel was known in the Iron Age or early historical period. However, the large-scale use of such steel was prevalent only in the medieval times. This article examines the presence of steel and its metallographic features in the iron artifacts retrieved from two archaeological sites, namely Ambal and Vallam, Tamil Nadu, India, with occupational evidence from the Iron Age to the medieval period through a number of scientific tests. Metallographic as well as mechanical tests were performed to identify the morphology and measure the strength respectively. Similarly, the chemical composition was determined to quantify the alloying elements in the material. The slag was exposed on the etched surface of the sample cut from axe. Microscopy and chemical composition analysis showed very fine bright dendrites of wüstite in the iron slag. The deterioration of samples was confirmed in microscopic and composition analysis. The result shows that the inhabitants of ancient Ambal and the Vallam were equipped with iron smelting technology and had the knowledge of steelmaking in the Iron Age. Keywords: Chemical composition, high-carbon steel, iron slag, mechanical test, microstructure. THROUGHOUT history, knowledge of iron has been chosen as one of the markers of urbanization and cultural development in human civilization. The iron objects are used for various purposes, such as agriculture and carpentry tools, weapons and household utensils. There have been many examples of the use of high carbon Indian crucible steel in the manufacture of various iron artifacts, such as the Delhi Iron Pillar (c. 400-420 CE) 1 and Damascus sword (c. 1100 CE) 2. The cultural sequence of Bronze Age and Iron Age between 3000 BCE and mid first millennium BCE is fairly categorized for North India and well-studied in the literature 3,4. Though there has been evidence of the smelting of iron ore to make iron in South India 5,6 , the antiquity of steel and indigenous iron metallurgy in this region has been a subject of discussion. The steelmaking process includes the smelting of iron ore and control of alloying elements during the process. Moreover, thermo-mechanical treatments are induced to improve the strength of the iron or steel objects. Numerous methods such as crucible steel, bloomery process and blast furnace technology are mentioned in the literature to produce cast iron and steel with a low to high percentage of carbon 7. In general, production of iron and steel is classified under two major categories: direct and indirect methods. In the direct method, the iron ore is reduced (crucible and bloomery process) below its melting point using reducing agents like carbon or charcoal. In ancient times, the bloomery process was often used to obtain iron. The melting point of pure iron, viz. 1535°C is reduced to around 1200°C by adding 2.1 wt% of carbon. The smelting of iron ore is performed inside the furnace after making alternate layers of ore and charcoal up to 0.3-0.5 m 3 and burning the hardwood charcoal to generate the required heat 8. Air is continuously supplied inside the furnace with the help of large bellows attached to clay-made tuyeres. The product formed called bloom consists of trapped slag and inclusion inside the pores of the reduced bloom. Therefore, the bloom is continuously hammered in the hot state to remove the slag and the unburnt fuelled charcoal, and reduce the porosity. The hammering of bloom modifies the shape of the product with ultra-fine grain microstructure. Bloomery processed product has a relatively lower percentage of carbon than the blast furnace technology. However, the percentage of carbon in the bloomery process (wrought iron <0.1% and steel 0.1-2.0%) is further changed during the heat treatment process to make iron harder by introducing carbon in iron by the carburizing process 9. Similarly, the steels smelted in a crucible made of clay and ash were called crucible steel. Iron ore was reduced to form slag and iron by heating with charcoal, ash, glass, and fluxes. The Indian crucible steel, also called wootz steel, was popular among the
A three-dimensional heat transfer and material flow-based model using experimentally measured thermophysical properties has been developed for friction stir welding (FSW) of Cu-0.8Cr-0.1Zr alloy. CuCrZr alloy is a precipitation-hardened copper alloy with good electrical and thermal conductivity and moderate strength at elevated temperatures. The temperature-dependent specific heat, thermal conductivity, and yield strength of the alloy were determined experimentally to develop a reliable and accurate numerical model. The results from numerical model were validated by performing suitable experiments for numerous tool rotational speeds and welding speeds during joining of 3-mm-thick CuCrZr alloy on a dedicated FSW. The temperature evolution across the welds was measured using thermocouples. The results from the developed numerical model were validated by comparing it with the measured weld thermal cycles, peak temperatures, and thermo-mechanical-affected zone (TMAZ) for various welds. Validation was also supported with microstructural evidences from the weld nugget zone and TMAZ. The developed model showed the capability to simulate FSW of CuCrZr alloy and predict the important results with reasonably good accuracy.
Polymer and polymer matrix composite materials are used in automotive applications owing to the high strength-to-weight ratio. However, the joining of polymer matrix composites is a challenging task due to the lower melting temperature, lower thermal conductivity, and agglomeration of reinforcements during fusion welding of these materials. Friction stir welding, a solid-state welding technology, is a suitable alternative for the welding of polymer matrix composites. The tool design, welding process parameters, and reinforcement content are some of the important factors that affect the material flow and microstructure in the welds. Several innovative modifications to conventional FSW, such as submerged FSW, heat-assisted FSW, friction stir spot welding, and friction riveting, have been suggested for defect-free welding of PMCs. Various weld properties such as tensile strength, hardness, shear bond strength, and impact strength have been studied for the FSW of PMCs. The weld defects have been analyzed and characterized. The numerical simulation of the FSW of PMCs has also been attempted by various researchers.
- Faculty of Materials Engineering
About Amit Arora
- Amit Arora currently works as Associate Professor of Materials Engineering, Indian Institute of Technology Gandhinagar, India. Amit does research in Materials Engineering and Manufacturing Engineering. Their most recent publication is 'Towards attaining dissimilar lap joint of CuCrZr alloy and 316L stainless steel using friction stir welding'.