Molybdenum trioxide (MoO3) powders with fiber and belt-like morphologies were synthesized through... more Molybdenum trioxide (MoO3) powders with fiber and belt-like morphologies were synthesized through a molten salt method using NH4NO3 as a molten salt. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential thermal analysis (TG–DTA), Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible absorption spectroscopy. The results revealed that the amount of NH4NO3 and temperature had an important effect on controlling the morphology of the obtained molybdates. With increasing the temperature from 550 C to 750 C, and also changing the MoO3/NH4NO3 molar ratio from 1:4 to 1:7, the width of the particles increases and the fiber-like morphology changes to the belt one. Furthermore, the band gap energy of MoO3 decreased from 2.76 eV to 2.71 eV as the temperature increased from 550 C to 750 C.
Synthesis of vanadium carbide–copper nanocomposite was achieved via mechanochemical combustion
me... more Synthesis of vanadium carbide–copper nanocomposite was achieved via mechanochemical combustion method from reactant mixture of V2O5, CuO, C and Mg powders. The obtained samples were characterized by X-ray diffraction (XRD), transmission electronmicroscopy (TEM) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). X-ray diffraction investigations indicated that the combustion products were V4C3, V2C and Cu phases. Microstructural studies showed that a nanostructured powder with a mean particle size of about 100 nm was procured in the samples milled for 90 min.
In this study, the effect of using phosphate bonding materials such as sodium hexametaphosphate (... more In this study, the effect of using phosphate bonding materials such as sodium hexametaphosphate (SHMP) and sodium tripolyphosphate was investigated in the presence of water and recycled magnesia carbon (MgO–C) refractory aggregates as raw materials. For this purpose, different compounds are prepared, and some parameters such as bulk density, volume per cent of apparent porosity and cold crushing strength weremeasured at different temperatures (200, 500 and 11008C), and phase and microstructure studies were performed by X-ray diffraction, SEM and energy dispersive spectroscopy. Statistically, effects of the factors were also determined using the analysis of variance method. Results indicated that MgO–C monolithic refractory samples were successfully produced from recycling the spent MgO–C bricks, and use of these phosphat ebinders especially that of 5 wt-% SHMP produce some phosphate bonds like Mg2P2O7, Mg3(PO4)2 and AlPO4 and improve the physical and mechanical properties.
The aim of this study was to synthesize glass ionomer-silk fiber composite and examining the effe... more The aim of this study was to synthesize glass ionomer-silk fiber composite and examining the effect of adding natural degummed silk fiber on the mechanical properties of glass ionomer cement (GIC). For this purpose, natural degummed silk fibers with 1 mm length and 13-16 µm diameter were added to the ceramic component of a commercial glass ionomer cement in 1, 3, and 5 wt. %. Compressive strength (CS), three-point flexural strength (FS) and diametral tensile strength (DTS) of the prepared glass ionomer-silk fiber were measured. Analysis of variance (ANOVA) was used to compare the obtained results. Moreover, SEM technique was used for the investigation of the surface morphology of the as-prepared composite and the fractured area. The results showed that the highest compressive strength, flexural strength and diametral tensile strength were obtained using 3, 3, and 5 wt. % of silk fiber, respectively. However, at 3 wt. % of silk fiber, all three measures of strength exhibited a significant increase compared to the commercial GIC. Therefore, it can be suggested that the addition of 3 wt. % silk fiber to the ceramic component of GIC is desired for dental restorations and orthopedic implant applications, where the maximum strength in all three modes of loading would be beneficial.
Glass Ionomer Cements (GICs) are one of the most important dental restorative materials. Improvem... more Glass Ionomer Cements (GICs) are one of the most important dental restorative materials. Improvement of biological and mechanical properties of these materials has been taken into consideration. The aim of this work was to preparation and characterization of GICs by melting method and evaluation of adding Hydroxyapatite (HA) micro and nanoparticles on compressive strength of GICs. In this research, the ceramic part of GIC was prepared using melting method, and micro and nano-hydroxyapatite were synthesized from natural bone. HA micro and nanoparticles were added to GICS in different weight percents (0, 1, 3, 5 and 7 wt.%). The microstructure of synthesized products, chemical composition of the ceramic part of glass ionomer cement and the size and shape of HA nanoparticles were studied by Scanning Electron Microscopy (SEM), X-ray Fluorescence (XRF) and Transmission Electron Microscopy (TEM), respectively. The phase analysis of GICs composite was carried out by X-ray Diffraction (XRD) technique. Finally, the compressive strength of composite samples were determined and compared. TEM confirmed the nanometric scale of hydroxyapatite particles. Results of the compression test showed that adding HA micro and nanoparticles with the values of less than 5% by weight had no distractive effect on compressive strength of GICs. The final result of this research was gaining GICs containing HA micro and nanoparticles with improved equivalent mechanical properties. The improvement of GICs properties in dentistry applications can be achieved by adding bioactive materials like HA micro and nanoparticles.
Statement of Problem: In order to increase the performance of glass ionomer cement, it is reinfor... more Statement of Problem: In order to increase the performance of glass ionomer cement, it is reinforced with metal powders, short fibers, bioceramics and other materials. Fluoroapatite (Ca 10 (PO 4) 6 F 2) is found in dental enamel and is usually used in dental materials due to its good chemical and physical properties. Objectives: In this study, the effects of the addition of synthesized fluoroapatite nanoceramic on the compressive strength and bioactivity of glass ionomer cement were investigated. Materials and Methods: The synthesized fluoroapatite nanoceramic particles (~ 70 nm) were incorporated into as-prepared glass ionomer powder and were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Moreover, the compressive strength values of the modified glass ionomer cements with 0, 1, 3 and 5 wt% of fluoroapatite were evaluated. Results: Results showed that glass ionomer cement containing 3 wt% fluoroapatite nanoparticles exhibited the highest compressive strength (102.6 ± 4) compared to the other groups, including control group. Furthermore, FTIR and SEM investigations indicated that after soaking the glass ionomer cement-3 wt% fluoroapatite composite in the simulated body fluid solution, the intensity of O-H, P-O and CO absorption bands increased as a result of the formation of apatite layer on the surface of the sample, and the rather flat and homogeneous surface of the cement became more porous and inhomogeneous. Conclusions: Addition of synthesized nano-fluoroapatite to as-prepared glass ionomer cement enhanced the compressive strength as well as nucleation of the calcium phosphate layer on the surface of the composite. This makes it a good candidate for dentistry and orthopedic applications.
Molybdenum trioxide (MoO3) powders with fiber and belt-like morphologies were synthesized through... more Molybdenum trioxide (MoO3) powders with fiber and belt-like morphologies were synthesized through a molten salt method using NH4NO3 as a molten salt. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential thermal analysis (TG–DTA), Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible absorption spectroscopy. The results revealed that the amount of NH4NO3 and temperature had an important effect on controlling the morphology of the obtained molybdates. With increasing the temperature from 550 C to 750 C, and also changing the MoO3/NH4NO3 molar ratio from 1:4 to 1:7, the width of the particles increases and the fiber-like morphology changes to the belt one. Furthermore, the band gap energy of MoO3 decreased from 2.76 eV to 2.71 eV as the temperature increased from 550 C to 750 C.
Synthesis of vanadium carbide–copper nanocomposite was achieved via mechanochemical combustion
me... more Synthesis of vanadium carbide–copper nanocomposite was achieved via mechanochemical combustion method from reactant mixture of V2O5, CuO, C and Mg powders. The obtained samples were characterized by X-ray diffraction (XRD), transmission electronmicroscopy (TEM) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). X-ray diffraction investigations indicated that the combustion products were V4C3, V2C and Cu phases. Microstructural studies showed that a nanostructured powder with a mean particle size of about 100 nm was procured in the samples milled for 90 min.
In this study, the effect of using phosphate bonding materials such as sodium hexametaphosphate (... more In this study, the effect of using phosphate bonding materials such as sodium hexametaphosphate (SHMP) and sodium tripolyphosphate was investigated in the presence of water and recycled magnesia carbon (MgO–C) refractory aggregates as raw materials. For this purpose, different compounds are prepared, and some parameters such as bulk density, volume per cent of apparent porosity and cold crushing strength weremeasured at different temperatures (200, 500 and 11008C), and phase and microstructure studies were performed by X-ray diffraction, SEM and energy dispersive spectroscopy. Statistically, effects of the factors were also determined using the analysis of variance method. Results indicated that MgO–C monolithic refractory samples were successfully produced from recycling the spent MgO–C bricks, and use of these phosphat ebinders especially that of 5 wt-% SHMP produce some phosphate bonds like Mg2P2O7, Mg3(PO4)2 and AlPO4 and improve the physical and mechanical properties.
The aim of this study was to synthesize glass ionomer-silk fiber composite and examining the effe... more The aim of this study was to synthesize glass ionomer-silk fiber composite and examining the effect of adding natural degummed silk fiber on the mechanical properties of glass ionomer cement (GIC). For this purpose, natural degummed silk fibers with 1 mm length and 13-16 µm diameter were added to the ceramic component of a commercial glass ionomer cement in 1, 3, and 5 wt. %. Compressive strength (CS), three-point flexural strength (FS) and diametral tensile strength (DTS) of the prepared glass ionomer-silk fiber were measured. Analysis of variance (ANOVA) was used to compare the obtained results. Moreover, SEM technique was used for the investigation of the surface morphology of the as-prepared composite and the fractured area. The results showed that the highest compressive strength, flexural strength and diametral tensile strength were obtained using 3, 3, and 5 wt. % of silk fiber, respectively. However, at 3 wt. % of silk fiber, all three measures of strength exhibited a significant increase compared to the commercial GIC. Therefore, it can be suggested that the addition of 3 wt. % silk fiber to the ceramic component of GIC is desired for dental restorations and orthopedic implant applications, where the maximum strength in all three modes of loading would be beneficial.
Glass Ionomer Cements (GICs) are one of the most important dental restorative materials. Improvem... more Glass Ionomer Cements (GICs) are one of the most important dental restorative materials. Improvement of biological and mechanical properties of these materials has been taken into consideration. The aim of this work was to preparation and characterization of GICs by melting method and evaluation of adding Hydroxyapatite (HA) micro and nanoparticles on compressive strength of GICs. In this research, the ceramic part of GIC was prepared using melting method, and micro and nano-hydroxyapatite were synthesized from natural bone. HA micro and nanoparticles were added to GICS in different weight percents (0, 1, 3, 5 and 7 wt.%). The microstructure of synthesized products, chemical composition of the ceramic part of glass ionomer cement and the size and shape of HA nanoparticles were studied by Scanning Electron Microscopy (SEM), X-ray Fluorescence (XRF) and Transmission Electron Microscopy (TEM), respectively. The phase analysis of GICs composite was carried out by X-ray Diffraction (XRD) technique. Finally, the compressive strength of composite samples were determined and compared. TEM confirmed the nanometric scale of hydroxyapatite particles. Results of the compression test showed that adding HA micro and nanoparticles with the values of less than 5% by weight had no distractive effect on compressive strength of GICs. The final result of this research was gaining GICs containing HA micro and nanoparticles with improved equivalent mechanical properties. The improvement of GICs properties in dentistry applications can be achieved by adding bioactive materials like HA micro and nanoparticles.
Statement of Problem: In order to increase the performance of glass ionomer cement, it is reinfor... more Statement of Problem: In order to increase the performance of glass ionomer cement, it is reinforced with metal powders, short fibers, bioceramics and other materials. Fluoroapatite (Ca 10 (PO 4) 6 F 2) is found in dental enamel and is usually used in dental materials due to its good chemical and physical properties. Objectives: In this study, the effects of the addition of synthesized fluoroapatite nanoceramic on the compressive strength and bioactivity of glass ionomer cement were investigated. Materials and Methods: The synthesized fluoroapatite nanoceramic particles (~ 70 nm) were incorporated into as-prepared glass ionomer powder and were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Moreover, the compressive strength values of the modified glass ionomer cements with 0, 1, 3 and 5 wt% of fluoroapatite were evaluated. Results: Results showed that glass ionomer cement containing 3 wt% fluoroapatite nanoparticles exhibited the highest compressive strength (102.6 ± 4) compared to the other groups, including control group. Furthermore, FTIR and SEM investigations indicated that after soaking the glass ionomer cement-3 wt% fluoroapatite composite in the simulated body fluid solution, the intensity of O-H, P-O and CO absorption bands increased as a result of the formation of apatite layer on the surface of the sample, and the rather flat and homogeneous surface of the cement became more porous and inhomogeneous. Conclusions: Addition of synthesized nano-fluoroapatite to as-prepared glass ionomer cement enhanced the compressive strength as well as nucleation of the calcium phosphate layer on the surface of the composite. This makes it a good candidate for dentistry and orthopedic applications.
Uploads
Papers by Sara Alizadeh
method from reactant mixture of V2O5, CuO, C and Mg powders. The obtained samples were characterized by X-ray diffraction (XRD), transmission electronmicroscopy (TEM) and scanning electron
microscopy (SEM) with energy dispersive spectroscopy (EDS). X-ray diffraction investigations indicated
that the combustion products were V4C3, V2C and Cu phases. Microstructural studies showed that a
nanostructured powder with a mean particle size of about 100 nm was procured in the samples milled
for 90 min.
the physical and mechanical properties.
method from reactant mixture of V2O5, CuO, C and Mg powders. The obtained samples were characterized by X-ray diffraction (XRD), transmission electronmicroscopy (TEM) and scanning electron
microscopy (SEM) with energy dispersive spectroscopy (EDS). X-ray diffraction investigations indicated
that the combustion products were V4C3, V2C and Cu phases. Microstructural studies showed that a
nanostructured powder with a mean particle size of about 100 nm was procured in the samples milled
for 90 min.
the physical and mechanical properties.