Showing 8 results for Cobalt
M. H. Fathi, Gh. Feizi, Sb. Moosavi, Gh. Gahanshahi, M. Salehi, A. Saatchi and V. Mortazavi,
Volume 20, Issue 1 (7-2001)
Abstract
Hydroxyapatite coatings have been used on metallic substrates in a variety of applications, including modifying the surface of human implants, bone osseointegration and biological fixation. In this paper, the effects of various kinds of metallic substrate on clinical and pathological results of in vivo tests are presented. Four kinds of endodontic implants i.e, stainless steel, cobalt base alloy, plasma sprayed hydroxyapatite coated stainless steel, plasma sprayed hydroxyapatite coated cobalt base alloy were prapared and implanted in mandibular canine of
cats. After a healing period of 4 months, investigation by SEM and histopathological interpretation and evaluation showed significant differences in tissue response and osseointegration between coated and non-coated metallic implants. It was concluded that the results were affected by the kind of metallic substrate .
Keywords: Hydroxyapatite coating, Dental endodontic implant, Osseointegration, Corrosion, Stainless steel,
Cobalt base alloy
M. M. Diband Khosravi and M. Abdollahiy,
Volume 24, Issue 1 (7-2005)
Abstract
Reductive leaching was used to dissolve metals, especially cobalt, present in Fars Tidar mine,. In this paper, cobalt ore was leached with sulphuric acid in the presence of phenol to determine the effects of various factors on leaching. These factors included temperature, acid concentration, time, phenol content, pulp density, and interaction between some of the parameters. The results indicated that temperature was more effective on SN ratio (Signal to Noise ratio) which was found to be about 80%. The effecst of time and acid concentration on SN ratio were also determined at about 8% and 4 %, respectively. Although the effect of phenol content on cobalt leaching was too low but dissolution of cobalt decreased in the absence of phenol. Therefore, it was concluded that phenol was one of the factors in effective the leaching process. Anyway, three parameters
including temperature, acid concentration, and time were selected as more effective parameters. Consequently optimum conditions can be obtained with high levels content of temperature, acid concentration, and time with low levels of phenol and pulp density.
P. Razmjouee, S. M. Mirkazemi,
Volume 34, Issue 1 (5-2015)
Abstract
In this investigation, the effect of Polyvinylpyrrolidone (PVP) additive on microstructure, morphology and magnetic properties of cobalt ferrite nanoparticles prepared by hydrothermal method was studied. X-ray diffraction (XRD) studies in different synthesis conditions showed the formation of cobalt ferrite and cobalt oxide. Comparing IR spectrum of PVP additive, sol prepared before hydrothermal process and C-0.1PVP3, 190 obtained by FTIR spectroscopy indicated the formation of bond between PVP and surface of metallic hydroxide and cobalt ferrite particles, which prevented them from growing and coarsening. Scanning electron microscope (SEM) was used to study the morphology of samples. According to vibration sample magnetometer (VSM) results, as PVP amount increases from 0.1 to 0.3 volume percent, coercive field increases from 298 to 684 Oe and saturation magnetization decreases from 58 to 51 emu/g.
H. Amiri, S. M. Mirkazemi, A. Beitollahi ,
Volume 34, Issue 2 (7-2015)
Abstract
In this investigation, the effect of heat treatment on magnetic properties of glass and nano-structured cobalt-ferrite glass-ceramic was studied. The glass was synthesized in the system of Na2O-Fe2O3-CoO-B2O3-SiO2. Based on DTA results, heat treatment was done at different times and temperatures. X-ray diffraction pattern of glass-ceramic showed the crystallization of CoFe2O4 and some nonmagnetic phases. The highest magnetization of 11.8 emu/g was obtained for the sample heat-treated for 2 hr at 670C in graphite bed. Average crystallite size of CoFe2O4 in this sample was 50 nm. Scanning Electron Microscopy (SEM) confirmed the formation of cobalt ferrite nanoparticles in the glass matrix.
M. Hakimi, P. Kameli, B. Aslibeiki, A. Faqeeh,
Volume 35, Issue 4 (2-2017)
Abstract
In this work, cobalt ferrite nanocrystallites were synthesized by air annealing of milled Co-Fe compound. Effect of annealing temperature on phase formation of cobalt ferrite and structural and magnetic properties of the product was studied. Analysis of annealed sample in 450 oC showed that around 46 weight percent of the specimen was changed to Co2FeO4. This value increased to 95 and 90% for 800 oC and 900 oC annealed samples respectively. Reduction of saturation magnetization under annealing was related to transformation of Co-Fe to cobalt ferrite. Increasing the value of saturation magnetization in 900 oC annealed sample compared to 800 oC one was attributed to decreased surface to volume ratio and crystallite size. The main reason of occurrence of maximum coercivity in 800 oC annealed sample was its low crystallite size.
M. Eshraghi, Z. Mosleh, M. Rahimi,
Volume 38, Issue 1 (6-2019)
Abstract
In this investigation, the structural and magnetic properties of Cr and Zn substituted Co ferrite with the general formula Co1-xZnxFe2-xCrxO4 (x= 0.1, 0.3, 0.5, 0.7) as prepared by sol- gel method were studied. The structural, morphological and magnetic properties of the samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM) and Vibrating sample magnetometer (VSM). XRD measurements along with the Rietveld refinement indicated that the prepared samples were single phase with the space group of Fd-3m. Results of SEM images also showed that the particles were in the nanosize range. Also, the magnetic properties of the samples indicated that the magnetization was first decreased, reaching the minimum value for x=0.1 sample; then it was increased. This behavior was related to the cation distribution at the tetrahedral and octahedral sites. Moreover, coercivity was significantly decreased with increasing the doping level due the decrease of magnetocrystalline anisotropy because of the nonmagnetic Zn ion substitution.
A. H. Kianfar, N. Eskandari, M. A. Arayesh,
Volume 39, Issue 2 (8-2020)
Abstract
In this research the synthesis of [Co(Salen)(PPh3)(H2O)]4[Fe(CN)6] and [Co(Salophen)(PPh3)(H2O)]4[Fe(CN)6] schiff base complexes was reported. Co3O4/CoFe2O4 magnetic nanoparticles were prepared by calcination of these complexes at 500, 550 and 600°C. Precursor complexes were identified by FT-IR and UV-Vis spectroscopy and their thermal behavior was studied via TG/DTA. Nanomagnetic samples were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FT-IR). Magnetic properties of the synthesized nanoparticles were studied using Vibrating Sample Magnetometer (VSM). Magnetic parameters such as saturation magnetization (Ms), remanent magnetization (Mr), coercive field (Hc) and squareness ratio (SQ = Mr/Ms) were determined at room temperature. Stoichiometry and approximate composition of the prepared samples were studied by Electron Diffraction X-ray spectroscopy (EDX). The prepared nanocomposites could be useful in some practical applications due to their high magnetization, good chemical stability and dispersion.
N. Ghobadi, S. A. Hosseini Moradi, M. Amirzade,
Volume 40, Issue 4 (3-2022)
Abstract
In this research, cobalt ferrite powders (CoFe2O4) and cobalt ferrite/reduced graphene oxide composite (CoFe2O4/RGO) were synthesized by the co-precipitation method. The phase structure, morphology, magnetic properties, and microwave absorption properties of the produced samples were investigated through various techniques. X-ray diffraction test indicated the successful formation of pure CoFe2O4 and its composites with RGO. According to the Scanning electron microscopy (SEM) images, most pure and composite samples’ particles were formed in a semi-spherical shape. The VNA test results showed the saturation magnetization of CoFe2O4 and the composite containing 5 wt.% and 10 wt.% of RGO, 71.6, 56, and 37 emu/g, respectively. Also, the network analyzer results demonstrated the maximum reflective losses in the X-band range due to the impact of microwaves on CoFe2O4 te was -5.5 db. This amount reached 21.5 dB with the addition of 10 wt.% RGO. Also, the wave input increased from 41% for the pure CoFe2O4 to 99.5% for the sample containing 10 wt.% RGO.
