Browsing by Author "Hekmatifar, M."

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Citation Count: 0
Bonding properties of Al/Sn/Al laminates fabricated via electrically press bonding process
(Elsevier, 2024) Daneshmand, Saeed; Salahshour, Soheıl; Sajadi, S. Mohammad; Jasim, Dheyaa J.; Salahshour, Soheil; Hekmatifar, M.; Nasajpour-Esfahani, Navid
In the late 1980s, electrically assisted press bonding gained attention in the semiconductor industry due to its ability to improve bond quality and reliability. This bonding method has several advantages, including improved bond strength, reduced bonding time, and the ability to bond materials that are traditionally challenging to bond. This connection method is commonly used in applications where high band strength, reliability, and electrical conductivity are critical, such as microelectronics manufacturing, semiconductor devices, and advanced packaging technologies. In this study, AA1100 bars were connected using an electrically assisted press connection process at current levels of 100A, 200A and 300A. Poor bond strength is an important drawback in bonding processes. Therefore, to solve this problem, Sn particles were used as a finishing process and filler metal to increase the bond strength of aluminum sheets during electric press joining. AA1100 bars were produced with different weight percentages (wt%) of Sn particles as interlayer filler at different levels of electric current. The results reveal that increasing the level of electric current and the weight percentage of Sn leads to stronger bond strength. In this study, a scanning electron microscope (SEM) is used to check the quality of the bond. It is worth mentioning that the analysis of the exfoliation surface by SEM is performed on the samples after the peeling test to check the quality of the bond. In addition, the findings reveal that the bond strength improves with Sn content and higher current levels due to the Joule heating effect in the electrical press bonding process.
Citation Count: 0
An innovative approach combination of powder metallurgy and accumulative press bonding to fabricate Al/ graphite nanocomposites and investigate the tribological and wear properties
(Elsevier B.V., 2025) Vini, M.H.; Basem, A.; Daneshmand, S.; Jasim, D.J.; Hekmatifar, M.; Salahshour, S.
In this study, Al/Gr Nanocomposites (NC) were fabricated using an innovative approach that is a combination of powder metallurgy (PM) and accumulative press bonding (APB). By this combination method, many of defects are removed from the composite matrix which improves the mechanical properties. The APB process is a unique technique that made it possible to create NCs with distinct properties. In simpler terms, this process involves compressing a series of overlapping bulky samples that achieves a specific reduction ratio, such as 50 %. It is worth noting that extensive research has been done to understand the properties of Al/Gr-NCs comprehensively. By increasing the Gr value up to 10 %, hardness and friction coefficient dropped and wear rate increased by 23 %, 214 % and 37 %, respectively. Focusing on the analysis of microstructural, and tribological properties (TP), with special emphasis on the effect of Gr content as an additive component. In addition, the use of a scanning electron microscope (SEM) has facilitated the study of the surface and microstructure of tribo–NC. The result of this study revealed desirable behaviors. It was observed that with the increase of Gr content, the hardness and friction coefficient (FC) of the NC samples decreased, while the density and WR rate of the samples increased. These results indicate the importance of Gr addition in adjusting the MP and TP of NCs. Finally, the combination of PM and the APB process offers a promising way to fabricate nanoparticle (NP)-reinforced materials with desirable MP. © 2024 Elsevier B.V.
Citation Count: 1
Investigating the effect of external heat flux on the thermal behaviour of hybrid paraffin-air heat sink: A molecular dynamics approach
(Elsevier, 2023) Wang, Ke; Salahshour, Soheıl; Alizadeh, As'ad; Al-Rubaye, Ameer H.; Nasajpour-Esfahani, Navid; Salahshour, Soheil; Hekmatifar, M.
One of today's concerns regarding energy storage units is the low rate of storage and release of thermal energy and, as a result, the efficiency loss in these units. Subsequently, different strategies are utilized to solve this concern, such as using phase change materials (PCMs) and nanostructures. The background is the low storage and release rate of thermal energy in energy storage units, which leads to efficiency loss. This issue concerns many applications, including energy storage in buildings, vehicles, and electronic devices. This study aims to investigate the effect of external heat flux (EHF) on the thermal efficiency of a specific heat sink by employing molecular dynamics (MD) simulation. After ensuring the simulated atomic structures are stable, EHF is applied to see how it affects the thermal behaviour of the combination. The obtained results show that by increasing the EHF applied to the prototype, the thermal behaviour of the structure improves. So, with the increase of EHF from 0.1 W/m2 to 0.5 W/m2, the heat flux and thermal conductivity (TC) increase from 212.27 W/m2 to 317.90 W/mK to 286.71 W/m2 and 340.03 W/mK. The findings significantly affect energy storage unit efficiency and can inform future research and development efforts.
Citation Count: 0
Investigating the effect of external magnetic field on preventing deposition process in wax/asphaltene nanostructure using molecular dynamics simulation
(Pergamon-elsevier Science Ltd, 2024) Shao, Jianguo; Al-Aragi, Nawfel M. H.; Jasim, Dheyaa J.; Abosaoda, Munthar Kadhim; Shomurotova, Shirin; Salahshour, Soheil; Hekmatifar, M.
Background
Citation Count: 0
Investigation of the arrangement of aluminum fins on the thermal behavior of lauric acid as a phase change material in a two-pipe heat exchanger by CFD simulation
(Elsevier Ltd, 2024) Liu, W.; Mokhtari, M.; Hussein, M.A.; Kumar, A.; Albayati, T.M.; Bains, P.S.; Hekmatifar, M.
Background: Phase change material (PCM) thermal storage systems store more thermal energy per unit volume than sensible heat storage systems. PCMs offer a potential solution to reduce energy consumption in various thermal engineering applications. This study aimed to examine how fin arrangement affected the thermal efficiency and melting time of PCMs. Methods: A two-dimensional numerical analysis of the melting process of lauric acid in a heat exchanger featuring two pipelines and fins was conducted using CFD simulation. In most previous investigations, the heat transfer fluid was a single-phase liquid. An enthalpy-porosity technique was used to model the solid and liquid phases of PCM. The governing equations were solved using the commercial software ANSYS Fluent 2021, and the pressure and velocity equations were coupled using the SIMPLE algorithm. Significant findings: The best model among the 13 tested was Model 5, which featured 6 fins and a consistent angle of 60°. For Model 5, the melting time was 1818.3 s. Due to sensible heating, the fin's temperature (Temp) rose gradually from 300 K to 318 K. Temp then gradually increased as the PCM melted in the phase transition zone between 316.5 K and 321.2 K. Once the phase transition was complete, the PCM's Temp steadily rose from 324 K to 340 K. In Model 5, the inner wall Temp and the maximum Temp of the PCM were closest, at 327.34 K and 333.55 K, respectively. The thermal shock between the PCM and the ambient Temp caused a peak heat flux at the beginning of the PCM loading process. © 2024 The Authors
Citation Count: 0
The pool boiling heat transfer of ammonia/Fe 3 O 4 nano-refrigerant in the presence of external magnetic field and heat flux: A molecular dynamics approach
(Pergamon-elsevier Science Ltd, 2024) An, Qing; Salahshour, Soheıl; Alizadeh, As 'ad; Kamoon, Saeed S.; AL-Yasiri, Mortatha; Zhang, Mengyan; Hekmatifar, M.
Pool boiling is distinguished by its capacity to eliminate excessive heat fluxes (HFs) at low temperatures. In recent decades, the optimal design of flooded evaporators elevated the significance of pool boiling HT with refrigerant to conserve natural resources and energy. The industry highly regards this process on account of its superior heat transfer (HT) coefficient in comparison to other HT mechanisms. Among the types of boiling, pool boiling has a special place due to its ability to remove HFs at low temperatures. This study was the first to investigate the boiling characteristics of the ammonia/Fe 3 O 4 nano -refrigerant in a copper (Cu) nanochannel (NC) through molecular dynamics (MD) simulations. The primary goal was to investigate the effect of external HF (EHF) and external magnetic field amplitude (EMFA) on nanostructures ' atomic behavior (AB) and thermal behavior (TB). The research findings indicate that increasing the applied EHF led to increased particle movement and the HT rate. By changing the EHF, boiling behavior in the nano -refrigerant may also be seen. Maximum (Max) velocity (Vel.) increased to 8.970 & Aring;/ps when the EHF increases to 0.5 W/m 2 . Atomic collisions and particle mobility both increase when the EHF increases. Therefore, the maximum temperature value increases to 359.46 K. When the EMFA applied to the nano -refrigerant reaches to 0.5 T, the maximum values of the parameters, such as the Temp. and the velocity, reach to 410.07 K, and 11.802 & Aring;/ps, respectively.