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Atanu Das,Hee-Seon Bang 대한용접·접합학회 2018 대한용접·접합학회지 Vol.36 No.5
Multi-material joining of aluminium to steel is mainly restricted due to their different thermo-physical properties, melting temperatures, low solubility and in particular, formation of brittle intermetallic phase layer at the joint interface. Various joining processes have been attempted to join aluminium and steel sheets with an aim to reduce the growth of phase layer by precise control of heat input. However, laser beam and arc based joining processes are popular among other joining processes due to their strict control of heat input with regulative metal transfer and flexibility to join intricate shapes. A critical survey in joining aluminium to steel sheets by laser beam and arc based joining processes are presented in the present work. The influence of various joining parameters such as heat input, filler wire types on the growth of intermetallic phase layer thickness and corresponding joint strength are analysed and reported subsequently.
Gas Metal Arc Lap Joining of Aluminium Alloys and Steel Sheets
Atanu Das,Amitava De 대한용접·접합학회 2018 대한용접·접합학회지 Vol.36 No.5
A coupled experimental and theoretical investigation on joining of aluminium and galvanized sheets in lap joint geometry using an advanced pulsed current gas metal arc based process is presented. The experimental study was focussed on finding suitable processing conditions to restrict the heat input, and minimize the growth of the phase layer thickness and the formation of Fe-Al intermetallic compounds along the joint interface. The theoretical study included the development of a three-dimensional heat conduction model to compute the temperature field and thermal cycles, and estimate the final joint bead profiles and phase layer thickness as a function of processing conditions. The estimated results are tested extensively for a wide range of experimental conditions. The experimentally measured and the corresponding computed results show that the dissimilar material combinations of aluminium and galvanized steel can be joined successfully by pulsed current gas metal arc with a precise control of processing conditions and heat input.
Comparisons between Dual and Tri Material Gate on a 32 nm Double Gate MOSFET
Arpan Dasgupta,Rahul Das,Shramana Chakraborty,Arka Dutta,Atanu Kundu,Chandan K. Sarkar 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.10
The paper reports a comparative analysis between the dual material gate double gate (DMG-DG) nMOSFET and the tri material gate double gate (TMG-DG) nMOSFET in terms of their analog and RF performance. Three different devices having the DMG-DG structure have been considered. Each of the devices have different higher workfunction material gate length (L1) to lower workfunction material gate length (L2) ratio (L1:L2). Along with the three devices, the performance of the TMG-DG nMOSFET is compared. The analog parameters considered for the comparison are the drain current (Ids), the transconductance (gm), the transconductance generation factor (gm/Ids) and the intrinsic gain (gmRo). The drain induced barrier lowering (DIBL) of the devices is compared. The RF analysis is performed using the non quasi static (NQS) approach. We consider the intrinsic gate to source capacitances (Cgs), the intrinsic gate to drain capacitance (Cgd), the intrinsic gate to source resistances (Rgs), the intrinsic gate to drain resistance (Rgd), the transport delay (τm), the unity current gain cut-off frequency (fT ) and the max frequency of oscillation (fmax) for the RF comparisons. A single stage amplifier is also implemented using the devices for a circuit comparison.
Hee‑Seon Bang,Seong Min Hong,Atanu Das,Han‑Sur Bang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5
Hybrid friction stir welding, adopting an external pre-heat source in front of the friction stir welding (FSW) tool, is knownas a way of overcoming the disadvantages of conventional FSW; lack of plastic flow and excessive tool wear. In joining ofaluminum alloy to steel, presence of intermetallics (IMC) is essential, but its excessive growth can degrade the joint qualityby its brittleness. In this study, joining of 2.5 mm thick Al5052 aluminum alloy and 1.4 mm thick DP590 high strength steelhas been carried out by FSW and TIG assisted hybrid friction stir welding (HFSW) through experiments and numericalanalysis. Joints characteristics of two process was compared to optimize the process parameters. A 3-D model was developedto estimate the thermal elastic–plastic characteristics of the joints. It was confirmed that the joint efficiency of HFSW jointshas been improved to 84% than that of FSW (74%). 2.74 μm thickness of IMC layer was formed in HFSW joints and satisfiedthe permissible thickness (under 10 μm). The maximum residual stress (σzz) in welding direction was slightly higherat the HFSW joints than at the FSW joints. The overall results from experiment and simulation confirmed that HFSW is aneffective way of joining Al5052 to DP590.