Sharif Digital Repository

In this study, ultra-fine grained Cu and Cu + carbon nanotube (CNT) nanocomposites were prepared through a processes combining flake powder metallurgy, hot pressing, and high-pressure torsion (HPT). The effects of grain refinement and CNT reinforcement on the microstructure, hardness, wear resistance, and corrosion behavior of the newly developed nanocomposites were investigated. The results indicated that the HPT process decreased the grain size of Cu and Cu + CNT by 67.7% and 68.1%, respectively, and increased their microhardness by 151% and 132%. The addition of CNTs substantially improved the tribological behavior of Cu by generating a mechanically mixed carbon- and oxide-rich layer.... 

Cubic phase Li7La3Zr2O12 (LLZO) is a promising solid electrolyte for next-generation Li-ion batteries. In this work, the combustion sol–gel technique is used to prepare an Al-doped LLZO solid electrolyte. The crystal structure is investigated, and the cubic phase is confirmed. Densification properties were investigated using SEM and optical dilatometry. The densification of the Al-doped sample takes place in two stages through two different shrinkage rates. Using 0.25 mol Al-dopant 94% relative density is achieved at 1100 °C. The effect of Al-doping on electrochemical properties is investigated in detail using AC impedance spectroscopy. The result indicates that the optimum concentration of... 

Graphene-based carbon hollow spheres (CHSs) fabrication, doped with 2-mercaptobenzimidazole (MBI) was successfully done in previous work. The active/barrier corrosion protection performance (CPP) of epoxy coatings was evaluated using salt spray test, electrochemical impedance spectroscopy (EIS), and scanning vibrating electrode technique (SVET). Results proved the active/barrier CPP enhancement of epoxy coatings in the presence of 3 wt. % MBI@CHSs. While the presence of MBI and empty CHSs in epoxy coatings did not further improve the active performance. An improvement in the adhesion loss of the epoxy coating, ca. 58 %, was observed in the presence of 3 wt. % MBI@CHSs. © 2021  

Commercial paints and coatings can serve as a protective barrier for metallic substrates in a corrosive environment. A considerable variety of nanostructures can be embedded in a polymeric coating to achieve both barrier and active protection. This research aims to elucidate the role of polyaniline (PANI) as an active polyelectrolyte modifier for the surface modification of mesoporous silica nanoparticles (MSNs) doped with zinc cations (Zn2+). To characterize the samples, we employed different techniques, including field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FTIR), Raman... 

In this study, a novel inorganic/organic hybrid pigment based on zinc cations/Ferula Asafoetida leaves extract (Zn-FALE) was synthesized, and its corrosion protection properties were investigated in a saline solution and an organic coating. Interactions of components between Zn2+ cations and FALE were assessed by thermo-gravimetric analysis (TGA) and ultraviolet-visible (UV–visible) spectroscopy. Corrosion inhibitive performance of FALE and Zn-FALE pigments in the solution phase and coating phase was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). TGA and UV–visible results revealed the proper chelation between inorganic and organic components of... 

In this study, ultra-fine grained Cu and Cu + carbon nanotube (CNT) nanocomposites were prepared through a processes combining flake powder metallurgy, hot pressing, and high-pressure torsion (HPT). The effects of grain refinement and CNT reinforcement on the microstructure, hardness, wear resistance, and corrosion behavior of the newly developed nanocomposites were investigated. The results indicated that the HPT process decreased the grain size of Cu and Cu + CNT by 67.7% and 68.1%, respectively, and increased their microhardness by 151% and 132%. The addition of CNTs substantially improved the tribological behavior of Cu by generating a mechanically mixed carbon- and oxide-rich layer.... 

The high aspect ratio and unique thermal and electrical characteristics of carbon nanofiber (CNF) made it an ideal physical barrier against the penetration of corrosive ions. However, the poor compatibility of the CNF with the polymer matrix and the lack of active corrosion inhibitors are the key limitations of this nanomaterial, resulting in short-term anti-corrosion resistance. An intelligent self-healing epoxy (EP) coating, including CNF modified with a polydopamine (PDA)-La3+ complex, was successfully fabricated to overcome these issues. Electrochemical impedance spectroscopy (EIS) evaluation implied that mild steel (MS) submerged in a 3.5 wt % NaCl solution containing the CNF-PDA-La... 

In this study, the effects of unmodified calcium zinc phosphate (UCZP) and modified calcium zinc phosphate (MCZP) nanopigments (NPs) on the rheological, mechanical, and corrosion protection performance (CPP) of the epoxy (EP) coatings were investigated. Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to study morphology and overall chemical structure of synthesized calcium zinc phosphate (CZP) NPs, respectively. The grafting of methyltriethoxysilane (MTES) molecules on the surface of CZP was assessed using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and... 

Two-dimensional MXenes are the newly emerging family of nanomaterials with competitive performance for nano-device development. Surface functional groups and abundant binding sites make these materials ideal candidates for sensor applications. Herein, we report the successful fabrication of a MXene-based nano-bio device for capturing, sensing, and filtering the Escherichia coli (E. coli) bacteria. Mannose carbohydrate, which binds strongly to E.coli's fimH protein via glucan multivalent interactions, is used as the bio-receptor element. MXene's structure was engineered to guarantee efficient E. coli capturing without mannose detachment. Electrochemical impedance spectroscopy (EIS) and cyclic... 

Magnesium (Mg) and its alloys have proved promising as biodegradable candidates for the repair of bone tissue. Despite the encouraging bio-related properties of Mg, its high corrosion rate in contact with body fluids still presents a major challenge. An efficient approach to address this issue is to provide a protective coating on Mg. The present research evaluates, for the first time, in vitro bioactivity and biocompatibility of a novel multifunctional composite coating based on poly(methyl methacrylate) (PMMA) biopolymer and bioactive glass (BG) particles on Mg-based implant. Electrophoretic deposition (EPD) was utilized to obtain this coating from a bi-component suspension. Coatings’... 

This research focused on the corrosion resistance and microstructure of hybrid additively manufactured (HAM) samples of AISI 420/CX (420/CX SS) stainless steels. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott–Schottky analyses as well as the electrochemical noise (EN) technique were used to evaluate the electrochemical behavior of the as-built and heat-treated HAM parts in NaCl solution. The results showed a more protective passive layer formed on the CX SS side. The distribution of Cr-rich M23C6 carbides in matrix of 420 SS side resulted in a lower corrosion resistance compared to the CX SS side. The noise data analysis confirmed an increase in the... 

In this research study, interfacial assembled nanoporous zeolitic imidazolate framework (ZIF-8) multiwalled oxidized carbon nanotubes (MW-OCNTs) were developed and introduced into a silane coating. To analyze the destructive behavior of the nanoparticles exposed to salty solutions with three distinctive pHs of 2, 7.5, and 12, various types of tests such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and inductively coupled plasma (ICP) were accomplished. The XRD test revealed that the main characteristic peaks of ZIF-8 were eliminated and/or their intensity decreased. In accordance with the obtained data from the XRD test, nanoparticles at pH = 2 had been... 

In this project, the protective effect of Biebersteinia multifida root extract (BMRE) against corrosion of 1018 low carbon steel (1018LCS) in HCl solutions was appraised by assessing weight loss, electrochemical impedance spectroscopy (EIS), and polarization at 25 °C. The maximum inhibitory efficacy for the concentration of 1 g/l of the BMRE was 92.8% at 25 °C after 2 h and increased to 95.3% after 24 h of immersion. Polarization experiments have shown that the extract in acidic solutions can act as a mixed corrosion inhibitor. The corrosion inhibitory efficacy of BMRE decreased with increasing temperature, and at all temperature settings studied, the adsorption of BMRE molecules on 1018 LCS... 

Cu2ZnSnS4 (CZTS) is a good candidate for cost-effective perovskite solar cells (PSCs) due to its direct bandgap with a value of 1.4–1.5 eV. In this study, we investigate CZTS ink as an inorganic hole-transport-layer (HTL) in CsMAFAPbIBr mixed halide PSCs. We study the cell efficiency and hole extraction from the perovskite layer for different thicknesses of HTL. The optimized device exhibits better hole selectivity, and the best efficiency of the device (12.84%) is achieved for the CZTS layer with a thickness of 159 nm. The prepared samples were also tested by open-circuit voltage decay analysis and electrochemical impedance spectroscopies. Results show that the optimized device effectively... 

Bipolar Plates (BPPs) are the most crucial component of the Polymer Electrolyte Membrane (PEM) fuel cell system. To improve fuel cell stack performance and lifetime, corrosion resistance and Interfacial Contact Resistance (ICR) enhancement are two essential factors for metallic BPPs. One of the most effective methods to achieve this purpose is adding a thin solid film of conductive coating on the surfaces of these plates. In the present study, 410 Stainless Steel (SS) was selected as a metallic bipolar plate. The coating process was performed using titanium nitride and chromium nitride by the Cathodic Arc Evaporation (CAE) method. The main focus of this study was to select the best coating... 

In this paper, a high-performance epoxy nanocomposite with dual active/barrier protection ability based on calcium zinc phosphate (CZP) nanopigment was fabricated. Then chemistry, morphology, and anti-corrosion ability of the commercial zinc phosphate (ZP) and CZP pigments were studied. By electrochemical techniques, the inhibition potency of the CZP nanopigment was examined in a NaCl solution on mild steel (MS) substance and compared with that of ZP. Results revealed a higher corrosion inhibition degree of the CZP compared to the ZP. The growth of a protective layer on the metal coupons exposed to the CZP extract was illustrated by X-ray photoelectron spectroscopy (XPS), field emission... 

Manganese dioxide/reduced graphene oxide (MnO2/RGO) nanocomposite material was synthesized by the in-situ anodic pulse electrodeposition method to fabricate symmetric supercapacitors. The effects of the pH value of the electrodeposition bath were considered on the properties of fabricated electrodes. Three pH values of 4, 7, and 10 were evaluated, and physicochemical properties were studied using field-emission scanning and transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, nitrogen gas sorption isotherm, and thermogravimetric analysis. The electrochemical evaluation was performed by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV),...