جستجوی مقالات مرتبط با کلیدواژه « Scanning Electron Microscopy (SEM) » در نشریات گروه « مواد و متالورژی »

In this study, hydroxyapatite was produced and produced from yellow fish bones by hydrothermal method at two temperatures of 150 and 200 °C using water and alcohol additives. X-ray diffraction (XRD) analysis, infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to study the fuzzy structure, identification of powder organic compounds and particle morphology, respectively. XRD results showed that the peaks related to hydroxyapatite are in the range . According to the obtained results, it was found that to form the structure of hydroxyapatite, a minimum temperature of 200 degrees Celsius with water additive solution is required. The FTIR results also showed that the peak of 1032 cm-1 belongs to the chemical group and the peak of 560 cm-1 belongs to . As a result, the obtained hydroxyapatite powder ( ) can be used in medical work.

The aim of this work is the characterization of the Co3O4 fibres, prepared by the electrospinning method. The investigation of the structural, morphological,optical, and magnetic properties of electrospun fibres at two different calcination temperatures was conducted by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Diffuse Reflectance Spectra (DRS), and Vibrating Sample Magnetometer (VSM). XRD indicates the cubic phase of the calcined Co3O4 fibres. The microstructural parameters such as crystallite size and its distribution are determined from the X-ray diffraction pattern analysis using the whole powder pattern modeling (WPPM) approach. The results obtained from the X-ray diffraction pattern analysis and crystallite size distribution shows an increase in the crystallite size with calcination temperature. The SEM images show the formation of randomly oriented fibres with diameters in the range of 200-250 nm after calcination. The DRS results show a decrease in the band gap energy with increasing calcination temperature. The magnetic analysis performed by VSM, confirms a paramagnetic phase of fibres at elevated calcination temperatur.

Strengthening of copper matrix by dispersion of metallic oxides particles as an efficient way to increase strength without losing thermal and electrical conductivities has been recognized for many years. Such a composite can withstand high temperatures and keep its properties. Such copper alloys have many applications especially in high temperature including resistance welding electrodes¡ electrical motors and switches. In the present work¡ at first¡ the Cu-1%Al solid solution was prepared by the mechanical alloying process via 48 hours of milling. Subsequently¡ 0.66 gr of copper oxide was added to Cu-1%Al solid solution and mechanically milled for different milling times of 0¡16¡ 32¡ 48 hours. The milled powder mixtures were investigated by X-Ray Diffraction and scanning electron microscopy techniques. The lattice parameter of Cu increased at first¡ but then decreased at longer milling times. The internal strain increased and the average Cu crystal size decreased during milling process.The particle size decreased during the whole process. With increasing annealing temprature from 450°C to 750°C¡ the microhardness values of samples decreased at the beginning but then increased. From these results¡ it can be concluded that nanosize aluminaparticles are formed in the copper matrix.

In this paper vertically aligned Multi-walled carbon nanotubes (VA-MWCNTs) have been successfully synthesized by chemical vapor deposition (CVD) using ethanol (C2H5OH) as a carbon source and Co as a catalyst on quartz substrate. The effects of growth time and growth temperature on MWCNT growth were studied in detail. At 45 min growth time, by increasing the growth temperature from 550 oC to 650 oC, the length and density of MWCNTs increase. At 750 oC, MWCNTs become spaghetti-like. The optimum growth conditions were found to be at growth temperature of 650 oC. At 650 oC, by increasing the growth time from 30 min to 75 min, the length of carbon nanotubes increases (from 2μm to 12μm approximately). The morphology and structure of the grown MWCNTs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy techniques.

In the present work, Ni-W-PCTFE nanocomposite coatings were electrodeposited in the presence of different concentrations of polychlorotrifluoroethylene (PCTFE) from the tartrate bath on the plates of copper. The effect of the concentration of PCTFE was investigated on the corrosion resistance. Surface morphology and composition of the nanocomposite coating were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) measurements. Corrosion resistance of produced coatings were evaluated using open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and polarization techniques in 3.5% wt NaCl solution. The results of these studies show a significant shift in the corrosion potential toward noble potentials, decrease in the corrosion current density and increase in the charge transfer resistance with the incorporating of PCTFE particles in the Ni-W matrix. While The lowest corrosion current (5 ×10-5A cm-2) and the highest charge transfers resistance (19686 Ω cm2) for nanocomposite coatings obtained from the bath containing 4 g/L PCTFE.

In this study، Aluminium nanoparticles were synthesized by arc discharge method applying direct current between aluminium electrodes in liquid medium without the need to vacuum equipment، heat exchangers، furnaces and inert gases. In situ coating process was applied to the nanoparticles. Sample analysis indicates that the particle size was less than 30 nm. In this study، it has been seen that the liquid medium affect the arc velocity، arc stability، morphology and composition of the nanoparticles. Nanoparticles were characterized by X-ray diffraction (XRD) and their surface morphology were studies by scanning electron microscopy (SEM). The accuracy of nanoparticles coating was also investigated via IR spectroscopy.

A nanoceramic hexafluorozirconic acid based conversion coating free of phosphate salts was investigated. The effect of solution pH on coating morphology and corrosion resistance was evaluated. Corrosion resistance of nanoceramic conversion coating on cold rolled steel (CRS) substrates in different solution pH (3.5, 4.5 and 5.5) was studied utilizing DC polarization and Electrochemical Impedance Spectroscopy (EIS). The polarization tests revealed that sample was coated in pH=4.5 have the lowest corrosion current density and nobler corrosion potential in comparison with other coated samples. The results of EIS showed that this sample (pH=4.5) has the highest polarization resistance and the lowest capacitance. According to bode diagrams, this sample indicated greater phase angle (at high frequencies) and impedance modulus (at low frequencies). The morphology of the conversion coating surface formed at different pH was investigated using Field Emission-Scanning Electron Microscopy (FE-SEM). Images revealed that the morphological structure changed with increasing pH value.