Ebrahim Ghasemi - Academia.edu (original) (raw)
Papers by Ebrahim Ghasemi
![Research paper thumbnail of Corrosion Inhibitor Release from Zn-Al-[PO43-]-[CO32-] Layered Double Hydroxide Nanoparticles](https://attachments.academia-assets.com/106078062/thumbnails/1.jpg)
](Progress in Color, Colorants and Coatings, Nov 1, 2016
n-Al layered double hydroxide (LDH) nanoparticles with carbonate as the charge balancing anion in... more n-Al layered double hydroxide (LDH) nanoparticles with carbonate as the charge balancing anion in the interlayer space were synthesized using co-precipitation method. Then, the carbonate base Zn-Al LDH nanoparticles were doped with phosphate ion via anion-exchange reaction to synthesize Zn-Al-[PO 4 3-]-[CO 3 2-]. The structure and composition were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric-differential thermal analysis (TG-DTA). Inductively coupled plasma-optical emission spectrometer (ICP-OES) was employed to measure the phosphate release ability of Zn-Al-[PO 4 3-]-[CO 3 2-] in the 3.5 wt% NaCl solution. Results showed that zinc cation can release along with phosphate anion during ion exchange process. Then, the corrosion inhibition of phosphate anion and zinc cation on mild steel specimens was assessed by electrochemical impedance spectroscopy (EIS) and polarization. Field emission-scanning electron microscopy (FE-SEM) was used to study the surface morphology of the mild steel specimens after exposure to the test solutions. The results indicated the significant impact of zinc and phosphorus concentration in test solution on the corrosion inhibition properties. Prog. Color Colorants Coat. 9 (2016), 233-248© Institute for Color Science and Technology.
Corrosion Science, 2017
A comparative study on corrosion inhibitive effect of nitrate and phosphate intercalated Zn-Al-la... more A comparative study on corrosion inhibitive effect of nitrate and phosphate intercalated Zn-Al-layered double hydroxides (LDHs) nanocontainers incorporated into a hybrid silane layer and their effect on cathodic delamination of epoxy topcoat
In powder injection molding process, the rheological properties of feedstocks significantly influ... more In powder injection molding process, the rheological properties of feedstocks significantly influences the steady flow and the uniform filling into the mold. In this study, we investigated the effect of micro and nano size particles of Al2O3 on the rheological properties of Mg-Al2O3 feedstocks. A binder system containing Paraffin wax, Bees wax, and Stearic acid was synthesized. This binder was mixed with pure Mg and Al2O3 powders in various proportions. The Al2O3 powders contained both nano- and micro-Al2O3 differing in concentration from one sample to another. Flow characteristics of the samples were then investigated under different circumstances of shear rate and temperature by means of a rotary rheometer. Viscosity of the feedstocks was found to be decreased with micro size Al2O3 content whereas increased via nano size Al2O3.
Journal of Energy Chemistry
Materials Chemistry and Physics
Abstract In the present study, a dual functional nanostructured Fe2O3@TiO2 pigment, known as a co... more Abstract In the present study, a dual functional nanostructured Fe2O3@TiO2 pigment, known as a cool pigment, is presented owning photocatalytic properties and NIR reflection. The Fe2O3@TiO2 nano pigments were prepared with different proportions of Fe2O3/TiO2 at 0.06, 0.62 and 1.24. Fe3+ precursors were used to producing Fe2O3 nanoparticles via co-precipitation method and coated with TiO2 using the sol-gel method. The synthesized pigments were specified by XRD, SEM, TEM, FTIR, BET, LC-MS, Ultraviolet–visible Spectroscopy, Near Infrared Reflectance and Photoluminescence Spectroscopy techniques. The photocatalytic properties of the synthesized nanocomposites were appraised by analyzing the degradation of acid red18 and reactive black 5 under UV irradiation. The results showed that the crystallization of Fe2O3 and TiO2 highly enhances NIR reflectance. Fe2O3/TiO2 content also showed effective role on the band gap of the nanocomposite, catalytic property, and NIR reflection. An enhanced photoactivity along with the highest NIR reflectance (73%) demonstrated for Fe2O3@TiO2 with Fe2O3/TiO2 = 0.06 compared to other supported Fe2O3. Furthermore, the brownish color of such pigments suggests that it could be a suitable candidate for cool color coating.
Materials Science and Engineering: C
Layered double hydroxide (LDH) nanoparticles (NPs) have potential applications for the loading an... more Layered double hydroxide (LDH) nanoparticles (NPs) have potential applications for the loading and controlled release of drugs. This study investigated the synthesis of Zn/Al-LDH using the co-precipitation and ion-exchange methods, coating with SiO2 NPs and precise control of the release of vitamin C (VC). The results showed that more VC could be loaded by ion exchange. The surface of the VC-loaded LDH NPs was coated with SiO2 using the sol-gel and physical mixing methods. The structure, surface morphology, drug loading and thermostability were characterized and the drug release profile and release kinetics of the intercalated LDHs were studied. It was found that the SiO2 NPs more uniformly coated the LDH surfaces using the sol-gel process than the physical mixing method. The release behavior of VC from the intercalated nanohybrid is well described by the Avrami-Erofe'ev and Elovich models in the slow and fast stages. The sol-gel coated LDH@SiO2 nanohybrid system showed sustained drug delivery compared to the physical mixing method. The overall VC release from LDH increased more than 3-fold after coating with SiO2 NPs. Taken together, the Zn/Al-LDH@SiO2 coated by sol-gel should be considered as a potential sustained-release drug delivery system for VC.
International Journal of Applied Ceramic Technology
Applied Surface Science
Abstract The adsorption mechanisms and kinetics of zinc cations at the graphene oxide (GO) nanosh... more Abstract The adsorption mechanisms and kinetics of zinc cations at the graphene oxide (GO) nanosheets-water interface were studied by experimental and theoretical approaches. Results showed that adsorption of zinc cations onto GO surface forms a monolayer and obeys Langmuir isotherm. Meanwhile, the kinetics of sorption best fits with the pseudo-second-order model, suggesting that the sorption process is more than one-step. Various characterization techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), ultraviolet-visible spectrophotometry (UV–Vis) and field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDS) were conducted to describe the mechanism of the adsorption process. EIS and polarization tests results showed that zinc cations adsorption on the GO sheets provided active corrosion inhibition on mild steel in the chloride solution. The zinc binding to GO surface was further probed from a theoretical perspective applying electronic quantum mechanics (QM) methods. Theoretical results clarified the adsorption of zinc cations onto active sites of GO sheets. The electronic-structure quantum mechanics approach revealed that zinc cation more strongly binds to the surface of GO(OH) compared with the other two mono-functionalized models namely GO(COOH) and GO(O). This finding was in good agreement with X-ray photoelectron spectroscopy (XPS) analysis.
Journal of Industrial and Engineering Chemistry
Abstract Herein, we demonstrated a facile non-covalent functionalization route to exploit the GO ... more Abstract Herein, we demonstrated a facile non-covalent functionalization route to exploit the GO sheets as an efficient carrier for high loading of Zn(II) corrosion inhibitor with the controllable slow release. The Zn(II) intercalated GO exhibited good compatibility with epoxy matrix stemming from the chemical and structural alterations as confirmed by Raman analysis along with XPS, FE-SEM and HRTEM. The kinetics of Zn(II) release from the GO carrier revealed the consistency of experimental data with the Higuchi model. EIS combined with cathodic disbondment tests results proved the dual-function active/passive corrosion mitigation of Zn(II) intercalated GO-Epoxy system.
Applied Catalysis B: Environmental
Abstract Designing durable and highly active photoelectrocatalysts for overall water splitting is... more Abstract Designing durable and highly active photoelectrocatalysts for overall water splitting is very challenging. Here, we report an easy method for synthesizing a highly efficient three-dimensional core-shell photoelectrocatalyst. This catalyst consists of cadmium sulfide as the core and nickel-cobalt layered double hydroxide as the shell, thus CdS@NiCo-LDH. The advantages of this catalyst are high specific surface area, rapid transfer of electrons, and open channels for the release of gaseous products, which lead to better oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline environments. The use of this catalyst in water decomposition for OER allows current density values of 10, 100, 500, and 1000 mA cm−2 at a voltage of 132, 198, 306, and 309 mV, respectively. Also, using this catalyst for HER allows current density values of 10 and 100 mA cm-2 at a voltage of 379 and 202 mV respectively.
International Journal of Engineering
This study investigates the effects of micro- and nano-sized SiC powder on the rheological behavi... more This study investigates the effects of micro- and nano-sized SiC powder on the rheological behavior of Al based feedstocks for powder injection molding (PIM). Different compositions of Al feedstocks with additions of micro and nano-SiC powder were prepared and their rheological properties were measured with a rotational rheometer. The effects of SiC content and shear rate were investigated and activation energies were compared amongst the feedstocks. The results showed that nano-SiC powder has a prominent effect on the viscosity and yield stress whereas micro-SiC does not have an effective role and the base micro-Al powder determines the overall rheological behavior of the feedstock. It was found that the feedstocks reveal pseudoplastic behavior at low shear rates and dilatancy at high shear rates. The critical shear rate (γcrit) was 100 s-1 for changing the rheological behavior. The activation energy of a given feedstock was found to increase with micro-SiC content while the reverse trend was observed for nano-SiC.
Journal of Materials Science: Materials in Medicine, 2016
Composite pastes composed of various amounts of melt-derived bioactive glass 52S4 (MG5) and polyc... more Composite pastes composed of various amounts of melt-derived bioactive glass 52S4 (MG5) and polycaprolactone (PCL) microspheres in sodium alginate solution were prepared. Rheological properties in both rotatory and oscillatory modes were evaluated. Injectability was measured as injection force versus piston displacement. In vitro calcium phosphate precipitation was also studied in simulated body fluid (SBF) and tracked using scanning electron microscopy, X-ray diffraction and FTIR analyses. All composite pastes were thixotropic in nature and exhibited shear thinning behavior. The magnitude of thixotropy decreased by adding 10-30 wt% PCL, while further amounts of PCL increased it again. Moreover, the composites were viscoelastic materials in which the elastic modulus was higher than viscous term. The pastes which were just made of MG5 or PCL had poor injectability, whereas the composites containing both of these constituents exhibited reasonable injectability. All pastes revealed adequate structural stability in contact with SBF solution. In vitro calcium phosphate precipitation was well observed on the paste made of MG5 and somewhat on the pastes with 10-40 wt% PCL, however the precipitated layer was amorphous in nature. Overall, the produced composites may be appropriate as injectable biomaterials for non-invasive surgeries but more biological evaluations are essential.
In recent years, corrosion protection of the steel structures by organic coatings has led to a lo... more In recent years, corrosion protection of the steel structures by organic coatings has led to a lot of cost payment. Organic coatings due to their barrier properties against corrosion species access to the steel surface can protect the steel against corrosion. However, the corrosive electrolyte diffusion into the coating matrix through porosities and damaged parts leads to the coating hydrolytic degradation resulting in the decrease of coating barrier performance. To overcome this problem and improve the corrosion protection properties of the coatings, various kinds of anti-corrosive pigments are used. Chromates are one of the most effective anti-corrosive pigments. Since chromate-based pigments have high toxicity and environmental hazards, researchers are tried to investigate the alternative materials that reduce environmental hazards and also have a good anti-corrosion properties. Due to the non-toxic, low cost and availability of the iron oxide based pigments, the researchers'...
Journal of Ceramic Processing Research
In this research, the effect of milling time and carbon sources was investigated on the β-SiC nan... more In this research, the effect of milling time and carbon sources was investigated on the β-SiC nanofiber formation via the carbothermal process. Carbon black and petroleum coke were used as carbon sources. They were mixed with microsilica separately; milled for different periods of time and fired at 1450 oC. Phase formation and microstructure of samples were studied using X-ray powder diffraction and scanning electron microscopy, respectively. The results indicated that millingbprocess for 5 h appreciably contributes to the formation of β-SiC phase. Moreover, it was revealed that the carbon black leads to formation of fiber-like SiC nonaparticles.
In powder injection molding process, the rheological properties of feedstocks significantly influ... more In powder injection molding process, the rheological properties of feedstocks significantly influences the steady flow and the uniform filling into the mold. In this study, we investigated the effect of micro and nano size particles of Al2O3 on the rheological properties of Mg-Al2O3 feedstocks. A binder system containing Paraffin wax, Bees wax, and Stearic acid was synthesized. This binder was mixed with pure Mg and Al2O3 powders in various proportions. The Al2O3 powders contained both nano- and micro-Al2O3 differing in concentration from one sample to another. Flow characteristics of the samples were then investigated under different circumstances of shear rate and temperature by means of a rotary rheometer. Viscosity of the feedstocks was found to be decreased with micro size Al2O3 content whereas increased via nano size Al2O3.
Carbon, 2015
ABSTRACT Surface modification of graphene oxide (GO) has been performed by grafting of polyisocya... more ABSTRACT Surface modification of graphene oxide (GO) has been performed by grafting of polyisocyanate (PI) resin. Results obtained from X-ray photo electron spectroscopy, thermal gravimetric analysis and X-ray diffraction analysis revealed that the PI resin chains were successfully attached onto the surface of GO nanosheets through covalent bonding with hydroxyl and carboxylic groups leading to amides and carbamate esters bonds formation. Subsequently, the PI functionalized GO sheets were incorporated into the polyurethane (PU) matrix. The X-ray diffraction analysis showed that surface modification of GO nanosheets with PI enhanced the level of exfoliation of PI–GO in the PU matrix. Scanning electron microscope analysis showed the enhanced interaction between GO and PU matrix after functionalization by PI resin. The electrochemical impedance spectroscopy and salt spray tests were performed to reveal the effects of addition of 0.1 wt.% GO and PI–GO nanosheets on the corrosion protection properties of the PU coating. Also, the adhesion loss of the coatings was obtained by pull-off adhesion test after 30 days immersion in 3.5 wt.% NaCl solution. It was found that incorporation of 0.1 wt.% surface modified GO nanosheets into the PU matrix resulted in significant improvement of the coating corrosion protection properties and ionic resistance.
Progress in Organic Coatings, 2015
ABSTRACT Potassium zinc phosphate (PZP) pigments were synthesized using different mole ratios of ... more ABSTRACT Potassium zinc phosphate (PZP) pigments were synthesized using different mole ratios of KOH/ZnCl2, i.e. 1.5, 2, 2.5, 3, 3.5 and 4. The inhibition effects of the pigments were studied in the extract solution by polarization test and electrochemical impedance spectroscopy (EIS). The surface morphology was studied by scanning electron microscope (SEM). Surface analysis was performed by X-ray photoelectron spectroscopy. Pigments were also incorporated into the epoxy coating and salt spray and pull-off tests were implemented to investigate its corrosion protection properties.
The Scientific World Journal, 2014
Toner is a main component of electrophotographic printing and copying processes. One of the most ... more Toner is a main component of electrophotographic printing and copying processes. One of the most important ingredients of toner is magnetite (Fe3O4) which provides the tribocharging property for toner particles. In this study, nano- and microparticles of Fe3O4were synthesized using the coprecipitation method and different amounts of lauric acid as a surfactant. The synthesized nano and micro Fe3O4was then used as the charge control agent to produce toner by emulsion aggregation. The Fe3O4and toner were characterized by X-ray powder diffraction (XRD), atomic gradient force magnetometry (AGFM), dynamic laser scattering (DLS), particle size analysis, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The results show that the optimum amount of surfactant not only reduced particle size but also reduced the magnetite properties of Fe3O4. It was found that the magnetite behavior of the toner is not similar to the Fe3O4used to produce it. Although small-sized ...
Science and Engineering of Composite Materials, 2014
This study aims to prepare optimal feedstock for fabrication of Al/SiC nanocomposites by the low-... more This study aims to prepare optimal feedstock for fabrication of Al/SiC nanocomposites by the low-pressure injection molding technique. For this purpose, micron-sized aluminum and nanosized SiC powders were mixed with different amounts of the binder consisting of 89 wt% paraffin wax, 9 wt% bees wax, and 2 wt% stearic acid. Rheometry analyses as well as the Weir model were utilized to determine the optimal feedstock with the desired rheological properties and high homogeneity. Considering powder to binder ratios, shear sensitivity, flow activation energy, and homogeneity within the rheometry analyses, the feedstock of 78 wt% powder loading is selected as the optimal sample for injection molding. Investigation of optimal feedstock by the scanning electron microscopy technique also verified the high homogeneity of this feedstock. In addition, it was observed that all of the feedstocks had thixotrop behavior.
Journal of Sol-Gel Science and Technology, Nov 1, 2014
In this paper, the influence of sol–gel surface modification of lithium zinc phosphate (LZP) pigm... more In this paper, the influence of sol–gel surface modification of lithium zinc phosphate (LZP) pigment by methacryloxy propyl trimethoxy silane on corrosion inhibition, dispersion stability and adhesion strengthwas studied. IR spectroscopy and thermogravimetric analysis confirmed that organic functional group was successfully grafted onto the LZP surface. EIS and polarizationmeasurements ofmild steel showed an improvement in corrosion resistance for the extract of surface modified pigment in 3.5 % NaCl solution which was connected to better solubility proved by ICP-OES. The dispersion stability of the pigment in epoxy resinwas found to be improved after surface modification. In addition, the adhesion strength of the epoxy coating containing surface modified pigment to mild steel after exposure to salt spray (5 % NaCl solution) was enhanced. The sol–gel surface modification had led to increase in hydrophobicity of the pigment particle surface, but simultaneously increased solubility of...
Progress in Color, Colorants and Coatings, Nov 1, 2016
n-Al layered double hydroxide (LDH) nanoparticles with carbonate as the charge balancing anion in... more n-Al layered double hydroxide (LDH) nanoparticles with carbonate as the charge balancing anion in the interlayer space were synthesized using co-precipitation method. Then, the carbonate base Zn-Al LDH nanoparticles were doped with phosphate ion via anion-exchange reaction to synthesize Zn-Al-[PO 4 3-]-[CO 3 2-]. The structure and composition were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric-differential thermal analysis (TG-DTA). Inductively coupled plasma-optical emission spectrometer (ICP-OES) was employed to measure the phosphate release ability of Zn-Al-[PO 4 3-]-[CO 3 2-] in the 3.5 wt% NaCl solution. Results showed that zinc cation can release along with phosphate anion during ion exchange process. Then, the corrosion inhibition of phosphate anion and zinc cation on mild steel specimens was assessed by electrochemical impedance spectroscopy (EIS) and polarization. Field emission-scanning electron microscopy (FE-SEM) was used to study the surface morphology of the mild steel specimens after exposure to the test solutions. The results indicated the significant impact of zinc and phosphorus concentration in test solution on the corrosion inhibition properties. Prog. Color Colorants Coat. 9 (2016), 233-248© Institute for Color Science and Technology.
Corrosion Science, 2017
A comparative study on corrosion inhibitive effect of nitrate and phosphate intercalated Zn-Al-la... more A comparative study on corrosion inhibitive effect of nitrate and phosphate intercalated Zn-Al-layered double hydroxides (LDHs) nanocontainers incorporated into a hybrid silane layer and their effect on cathodic delamination of epoxy topcoat
In powder injection molding process, the rheological properties of feedstocks significantly influ... more In powder injection molding process, the rheological properties of feedstocks significantly influences the steady flow and the uniform filling into the mold. In this study, we investigated the effect of micro and nano size particles of Al2O3 on the rheological properties of Mg-Al2O3 feedstocks. A binder system containing Paraffin wax, Bees wax, and Stearic acid was synthesized. This binder was mixed with pure Mg and Al2O3 powders in various proportions. The Al2O3 powders contained both nano- and micro-Al2O3 differing in concentration from one sample to another. Flow characteristics of the samples were then investigated under different circumstances of shear rate and temperature by means of a rotary rheometer. Viscosity of the feedstocks was found to be decreased with micro size Al2O3 content whereas increased via nano size Al2O3.
Journal of Energy Chemistry
Materials Chemistry and Physics
Abstract In the present study, a dual functional nanostructured Fe2O3@TiO2 pigment, known as a co... more Abstract In the present study, a dual functional nanostructured Fe2O3@TiO2 pigment, known as a cool pigment, is presented owning photocatalytic properties and NIR reflection. The Fe2O3@TiO2 nano pigments were prepared with different proportions of Fe2O3/TiO2 at 0.06, 0.62 and 1.24. Fe3+ precursors were used to producing Fe2O3 nanoparticles via co-precipitation method and coated with TiO2 using the sol-gel method. The synthesized pigments were specified by XRD, SEM, TEM, FTIR, BET, LC-MS, Ultraviolet–visible Spectroscopy, Near Infrared Reflectance and Photoluminescence Spectroscopy techniques. The photocatalytic properties of the synthesized nanocomposites were appraised by analyzing the degradation of acid red18 and reactive black 5 under UV irradiation. The results showed that the crystallization of Fe2O3 and TiO2 highly enhances NIR reflectance. Fe2O3/TiO2 content also showed effective role on the band gap of the nanocomposite, catalytic property, and NIR reflection. An enhanced photoactivity along with the highest NIR reflectance (73%) demonstrated for Fe2O3@TiO2 with Fe2O3/TiO2 = 0.06 compared to other supported Fe2O3. Furthermore, the brownish color of such pigments suggests that it could be a suitable candidate for cool color coating.
Materials Science and Engineering: C
Layered double hydroxide (LDH) nanoparticles (NPs) have potential applications for the loading an... more Layered double hydroxide (LDH) nanoparticles (NPs) have potential applications for the loading and controlled release of drugs. This study investigated the synthesis of Zn/Al-LDH using the co-precipitation and ion-exchange methods, coating with SiO2 NPs and precise control of the release of vitamin C (VC). The results showed that more VC could be loaded by ion exchange. The surface of the VC-loaded LDH NPs was coated with SiO2 using the sol-gel and physical mixing methods. The structure, surface morphology, drug loading and thermostability were characterized and the drug release profile and release kinetics of the intercalated LDHs were studied. It was found that the SiO2 NPs more uniformly coated the LDH surfaces using the sol-gel process than the physical mixing method. The release behavior of VC from the intercalated nanohybrid is well described by the Avrami-Erofe'ev and Elovich models in the slow and fast stages. The sol-gel coated LDH@SiO2 nanohybrid system showed sustained drug delivery compared to the physical mixing method. The overall VC release from LDH increased more than 3-fold after coating with SiO2 NPs. Taken together, the Zn/Al-LDH@SiO2 coated by sol-gel should be considered as a potential sustained-release drug delivery system for VC.
International Journal of Applied Ceramic Technology
Applied Surface Science
Abstract The adsorption mechanisms and kinetics of zinc cations at the graphene oxide (GO) nanosh... more Abstract The adsorption mechanisms and kinetics of zinc cations at the graphene oxide (GO) nanosheets-water interface were studied by experimental and theoretical approaches. Results showed that adsorption of zinc cations onto GO surface forms a monolayer and obeys Langmuir isotherm. Meanwhile, the kinetics of sorption best fits with the pseudo-second-order model, suggesting that the sorption process is more than one-step. Various characterization techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), ultraviolet-visible spectrophotometry (UV–Vis) and field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDS) were conducted to describe the mechanism of the adsorption process. EIS and polarization tests results showed that zinc cations adsorption on the GO sheets provided active corrosion inhibition on mild steel in the chloride solution. The zinc binding to GO surface was further probed from a theoretical perspective applying electronic quantum mechanics (QM) methods. Theoretical results clarified the adsorption of zinc cations onto active sites of GO sheets. The electronic-structure quantum mechanics approach revealed that zinc cation more strongly binds to the surface of GO(OH) compared with the other two mono-functionalized models namely GO(COOH) and GO(O). This finding was in good agreement with X-ray photoelectron spectroscopy (XPS) analysis.
Journal of Industrial and Engineering Chemistry
Abstract Herein, we demonstrated a facile non-covalent functionalization route to exploit the GO ... more Abstract Herein, we demonstrated a facile non-covalent functionalization route to exploit the GO sheets as an efficient carrier for high loading of Zn(II) corrosion inhibitor with the controllable slow release. The Zn(II) intercalated GO exhibited good compatibility with epoxy matrix stemming from the chemical and structural alterations as confirmed by Raman analysis along with XPS, FE-SEM and HRTEM. The kinetics of Zn(II) release from the GO carrier revealed the consistency of experimental data with the Higuchi model. EIS combined with cathodic disbondment tests results proved the dual-function active/passive corrosion mitigation of Zn(II) intercalated GO-Epoxy system.
Applied Catalysis B: Environmental
Abstract Designing durable and highly active photoelectrocatalysts for overall water splitting is... more Abstract Designing durable and highly active photoelectrocatalysts for overall water splitting is very challenging. Here, we report an easy method for synthesizing a highly efficient three-dimensional core-shell photoelectrocatalyst. This catalyst consists of cadmium sulfide as the core and nickel-cobalt layered double hydroxide as the shell, thus CdS@NiCo-LDH. The advantages of this catalyst are high specific surface area, rapid transfer of electrons, and open channels for the release of gaseous products, which lead to better oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline environments. The use of this catalyst in water decomposition for OER allows current density values of 10, 100, 500, and 1000 mA cm−2 at a voltage of 132, 198, 306, and 309 mV, respectively. Also, using this catalyst for HER allows current density values of 10 and 100 mA cm-2 at a voltage of 379 and 202 mV respectively.
International Journal of Engineering
This study investigates the effects of micro- and nano-sized SiC powder on the rheological behavi... more This study investigates the effects of micro- and nano-sized SiC powder on the rheological behavior of Al based feedstocks for powder injection molding (PIM). Different compositions of Al feedstocks with additions of micro and nano-SiC powder were prepared and their rheological properties were measured with a rotational rheometer. The effects of SiC content and shear rate were investigated and activation energies were compared amongst the feedstocks. The results showed that nano-SiC powder has a prominent effect on the viscosity and yield stress whereas micro-SiC does not have an effective role and the base micro-Al powder determines the overall rheological behavior of the feedstock. It was found that the feedstocks reveal pseudoplastic behavior at low shear rates and dilatancy at high shear rates. The critical shear rate (γcrit) was 100 s-1 for changing the rheological behavior. The activation energy of a given feedstock was found to increase with micro-SiC content while the reverse trend was observed for nano-SiC.
Journal of Materials Science: Materials in Medicine, 2016
Composite pastes composed of various amounts of melt-derived bioactive glass 52S4 (MG5) and polyc... more Composite pastes composed of various amounts of melt-derived bioactive glass 52S4 (MG5) and polycaprolactone (PCL) microspheres in sodium alginate solution were prepared. Rheological properties in both rotatory and oscillatory modes were evaluated. Injectability was measured as injection force versus piston displacement. In vitro calcium phosphate precipitation was also studied in simulated body fluid (SBF) and tracked using scanning electron microscopy, X-ray diffraction and FTIR analyses. All composite pastes were thixotropic in nature and exhibited shear thinning behavior. The magnitude of thixotropy decreased by adding 10-30 wt% PCL, while further amounts of PCL increased it again. Moreover, the composites were viscoelastic materials in which the elastic modulus was higher than viscous term. The pastes which were just made of MG5 or PCL had poor injectability, whereas the composites containing both of these constituents exhibited reasonable injectability. All pastes revealed adequate structural stability in contact with SBF solution. In vitro calcium phosphate precipitation was well observed on the paste made of MG5 and somewhat on the pastes with 10-40 wt% PCL, however the precipitated layer was amorphous in nature. Overall, the produced composites may be appropriate as injectable biomaterials for non-invasive surgeries but more biological evaluations are essential.
In recent years, corrosion protection of the steel structures by organic coatings has led to a lo... more In recent years, corrosion protection of the steel structures by organic coatings has led to a lot of cost payment. Organic coatings due to their barrier properties against corrosion species access to the steel surface can protect the steel against corrosion. However, the corrosive electrolyte diffusion into the coating matrix through porosities and damaged parts leads to the coating hydrolytic degradation resulting in the decrease of coating barrier performance. To overcome this problem and improve the corrosion protection properties of the coatings, various kinds of anti-corrosive pigments are used. Chromates are one of the most effective anti-corrosive pigments. Since chromate-based pigments have high toxicity and environmental hazards, researchers are tried to investigate the alternative materials that reduce environmental hazards and also have a good anti-corrosion properties. Due to the non-toxic, low cost and availability of the iron oxide based pigments, the researchers'...
Journal of Ceramic Processing Research
In this research, the effect of milling time and carbon sources was investigated on the β-SiC nan... more In this research, the effect of milling time and carbon sources was investigated on the β-SiC nanofiber formation via the carbothermal process. Carbon black and petroleum coke were used as carbon sources. They were mixed with microsilica separately; milled for different periods of time and fired at 1450 oC. Phase formation and microstructure of samples were studied using X-ray powder diffraction and scanning electron microscopy, respectively. The results indicated that millingbprocess for 5 h appreciably contributes to the formation of β-SiC phase. Moreover, it was revealed that the carbon black leads to formation of fiber-like SiC nonaparticles.
In powder injection molding process, the rheological properties of feedstocks significantly influ... more In powder injection molding process, the rheological properties of feedstocks significantly influences the steady flow and the uniform filling into the mold. In this study, we investigated the effect of micro and nano size particles of Al2O3 on the rheological properties of Mg-Al2O3 feedstocks. A binder system containing Paraffin wax, Bees wax, and Stearic acid was synthesized. This binder was mixed with pure Mg and Al2O3 powders in various proportions. The Al2O3 powders contained both nano- and micro-Al2O3 differing in concentration from one sample to another. Flow characteristics of the samples were then investigated under different circumstances of shear rate and temperature by means of a rotary rheometer. Viscosity of the feedstocks was found to be decreased with micro size Al2O3 content whereas increased via nano size Al2O3.
Carbon, 2015
ABSTRACT Surface modification of graphene oxide (GO) has been performed by grafting of polyisocya... more ABSTRACT Surface modification of graphene oxide (GO) has been performed by grafting of polyisocyanate (PI) resin. Results obtained from X-ray photo electron spectroscopy, thermal gravimetric analysis and X-ray diffraction analysis revealed that the PI resin chains were successfully attached onto the surface of GO nanosheets through covalent bonding with hydroxyl and carboxylic groups leading to amides and carbamate esters bonds formation. Subsequently, the PI functionalized GO sheets were incorporated into the polyurethane (PU) matrix. The X-ray diffraction analysis showed that surface modification of GO nanosheets with PI enhanced the level of exfoliation of PI–GO in the PU matrix. Scanning electron microscope analysis showed the enhanced interaction between GO and PU matrix after functionalization by PI resin. The electrochemical impedance spectroscopy and salt spray tests were performed to reveal the effects of addition of 0.1 wt.% GO and PI–GO nanosheets on the corrosion protection properties of the PU coating. Also, the adhesion loss of the coatings was obtained by pull-off adhesion test after 30 days immersion in 3.5 wt.% NaCl solution. It was found that incorporation of 0.1 wt.% surface modified GO nanosheets into the PU matrix resulted in significant improvement of the coating corrosion protection properties and ionic resistance.
Progress in Organic Coatings, 2015
ABSTRACT Potassium zinc phosphate (PZP) pigments were synthesized using different mole ratios of ... more ABSTRACT Potassium zinc phosphate (PZP) pigments were synthesized using different mole ratios of KOH/ZnCl2, i.e. 1.5, 2, 2.5, 3, 3.5 and 4. The inhibition effects of the pigments were studied in the extract solution by polarization test and electrochemical impedance spectroscopy (EIS). The surface morphology was studied by scanning electron microscope (SEM). Surface analysis was performed by X-ray photoelectron spectroscopy. Pigments were also incorporated into the epoxy coating and salt spray and pull-off tests were implemented to investigate its corrosion protection properties.
The Scientific World Journal, 2014
Toner is a main component of electrophotographic printing and copying processes. One of the most ... more Toner is a main component of electrophotographic printing and copying processes. One of the most important ingredients of toner is magnetite (Fe3O4) which provides the tribocharging property for toner particles. In this study, nano- and microparticles of Fe3O4were synthesized using the coprecipitation method and different amounts of lauric acid as a surfactant. The synthesized nano and micro Fe3O4was then used as the charge control agent to produce toner by emulsion aggregation. The Fe3O4and toner were characterized by X-ray powder diffraction (XRD), atomic gradient force magnetometry (AGFM), dynamic laser scattering (DLS), particle size analysis, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The results show that the optimum amount of surfactant not only reduced particle size but also reduced the magnetite properties of Fe3O4. It was found that the magnetite behavior of the toner is not similar to the Fe3O4used to produce it. Although small-sized ...
Science and Engineering of Composite Materials, 2014
This study aims to prepare optimal feedstock for fabrication of Al/SiC nanocomposites by the low-... more This study aims to prepare optimal feedstock for fabrication of Al/SiC nanocomposites by the low-pressure injection molding technique. For this purpose, micron-sized aluminum and nanosized SiC powders were mixed with different amounts of the binder consisting of 89 wt% paraffin wax, 9 wt% bees wax, and 2 wt% stearic acid. Rheometry analyses as well as the Weir model were utilized to determine the optimal feedstock with the desired rheological properties and high homogeneity. Considering powder to binder ratios, shear sensitivity, flow activation energy, and homogeneity within the rheometry analyses, the feedstock of 78 wt% powder loading is selected as the optimal sample for injection molding. Investigation of optimal feedstock by the scanning electron microscopy technique also verified the high homogeneity of this feedstock. In addition, it was observed that all of the feedstocks had thixotrop behavior.
Journal of Sol-Gel Science and Technology, Nov 1, 2014
In this paper, the influence of sol–gel surface modification of lithium zinc phosphate (LZP) pigm... more In this paper, the influence of sol–gel surface modification of lithium zinc phosphate (LZP) pigment by methacryloxy propyl trimethoxy silane on corrosion inhibition, dispersion stability and adhesion strengthwas studied. IR spectroscopy and thermogravimetric analysis confirmed that organic functional group was successfully grafted onto the LZP surface. EIS and polarizationmeasurements ofmild steel showed an improvement in corrosion resistance for the extract of surface modified pigment in 3.5 % NaCl solution which was connected to better solubility proved by ICP-OES. The dispersion stability of the pigment in epoxy resinwas found to be improved after surface modification. In addition, the adhesion strength of the epoxy coating containing surface modified pigment to mild steel after exposure to salt spray (5 % NaCl solution) was enhanced. The sol–gel surface modification had led to increase in hydrophobicity of the pigment particle surface, but simultaneously increased solubility of...