Showing 28 results for Ceramic
A. Khakzadshahandashti, N.varahram, P. Davami,
Volume 11, Issue 2 (6-2014)
Abstract
This article examines the Weibull statistical analysis that was used for investigating the effect of melt
filtration on tensile properties and defects formed inside the casting. Forming and entrapping of double oxide films
have been explained by using the context of critical velocity of melt in the runner. SutCast software results were used
to examine the amounts of the velocity of melt as such. SEM/EDX analysis is used to observe the presence of double
oxide films in the fracture surfaces of the tensile specimens. The article goes on to propose that castings made with
foam filters with smaller pores show higher mechanical properties and reliability due to higher Weibull modulus and
fewer defects
A. Mohammadpour, S. M. Mirkazemi, A. Beitollahi,
Volume 12, Issue 3 (9-2015)
Abstract
In the present study, the feasibility of α-Fe ferromagnetic phase formation in glass and glass-ceramic by
reduction in hydrogen atmosphere have been investigated. The glass with the composition of 35Na
2
O–24Fe2O3–20B
2O3
–
20SiO
2
–1ZnO (mol %) was melted and quenched by using a twin roller technique. As quenched glass flakes were heat
treated in the range of 400-675 °C for 1-2 h in hydrogen atmosphere, which resulted in reduction of iron cations to α-Fe
and FeO. The reduction of iron cations in glass was not completely occurred. Saturation magnetization of these samples
was 8-37 emu g -1
. For the formation of glass ceramic, As quenched glass flakes heat treated at 590 °C for 1 h. Heat
treatment of glass ceramic containing magnetite at 675°C in hydrogen atmosphere for 1 h led to reduction of almost all of
the iron cations to α-Fe. Saturation magnetization of this sample increased from 19.8 emu g
-1
for glass ceramic to 67 emu
g
-1
A. Izadpanahi, S. Baghshahi, A. Shalbaf Zadeh,
Volume 13, Issue 3 (9-2016)
Abstract
In the following research, Lead magnesium niobate relaxor ferroelectric (PMN-PZT) ceramic powders were synthesized using the combustion method grand urea as the fuel for the first time. The starting materials used were lead nitrate, magnesium acetate, niobium oxide, zirconium nitrate, titanium oxide.
The raw materials were first mixed using the general formula of (1-x)Pb(Mg1/3Nb2/3)O3-xPb(Zr0.52Ti0.48)O3, with x=0.3. The synthesized powders were characterized using XRD, SEM and FTIR spectroscopy techniques. The X-ray diffraction patterns revealed that the structure of the prepared samples were tetragonal at 500,600,700 and 800 oC. However, the monoclinic phase was detected in the samples calcined at 800 oC and the amount of pyrocholore phase also drastically decreased at this temperature. The band gap widths of the samples were measured via UV spectroscopy in the wave number range of 400-4000cm-1. The results show that by increasing the calcination temperature, the band gap width of the prepared samples decreases. SEM micrographs verify that by rising the calcination temperature, the structure of the prepared samples becomes more homogenous.
G. Maghouli, B. Eftekhari Yekta,
Volume 15, Issue 1 (3-2018)
Abstract
Commercial dental lithium disilicate based glass-ceramics containing various amounts of P2O5 were synthesized. Regarding the crystallization behavior and physico-chemical properties of the glasses, the optimum percent of P2O5 was determined.as 8 %wt.
Crystallization behavior of the glasses was investigated by X-ray diffraction (XRD) and differential thermal analysis (DTA). The micro-hardness and chemical resistance of both glass and glass-ceramic searies were also determined.
According to our results, lithium phosphate was precipitated prior to crystallization of the main phases, i.e lithium meta silicate and lithium disilicate. This early precipitation led to evacuation of residual glass phase from lithium ions, which caused increasing the viscosity of glass and so shifting of crystallization to higher temperatures.
In addition, increasing in P2O5 amounts and consequently increasing in Li3PO4, led to significant decrease in the crystallite size and aspect ratio of crystals.
Furthermore, while the chemical resistance of the glasses was decreased with P2O5, it was increased with P2O5 after heat treatment process.
The chemical solubility of these three glass-ceramics was between 2080~1188 μg/cm2.
E. Shahmohamadi, A. Mirhabibi, F. Golestanifard,
Volume 17, Issue 1 (3-2020)
Abstract
In the present study, a soft computing method namely the group method of data handling (GMDH) is applied to develop a new and efficient predictive model for prediction of conversion percentage of silicon. A comprehensive database is obtained from experimental studies in literature. Several effective parameters like time, temperature, nitrogen percentage, pellet size and silicon particle size are considered. The performance of the model is evaluated through statistical analysis. Moreover, the silicon nitridation was performed in 1573 k and results were evaluated against model results for validation of the model. Furthermore, the performance and efficiency of the GMDH model is confirmed against the two most common analytical models. The most effective parameters in estimating the conversion percentage are determined through sensitivity analysis based on the Gamma Test. Finally, the robustness of the developed model is verified through parametric analysis.
S.m. Moussavi Janbesarayi, M. Mohebi, S. Baghshahi, S.a. Ahmad Alem, E. Irom,
Volume 17, Issue 2 (6-2020)
Abstract
Overusing nitrogen fertilizer causes some serious problems for water resources, soil, and agriculture products. Researchers have been trying to develop effective means which may use less amount of fertilizers containing nitrogen. In this work, cost-effective ceramic granule adsorbent was prepared to be used as a fertilizer carrier of controlled release behavior. A mixture of 70 wt.% domestic kaolin and 30 wt.% gibbsite was used to produce the granules. By utilizing thermal analysis of raw granule, the calcination temperatures were obtained and the effect of various calcination temperatures of 500, 600, and 700˚C on the water adsorption was studied. The characteristics of granules were investigated by XRD, BET, FTIR, and SEM analyses. The results showed that by increasing the calcination temperature, the crystal structure of the granules was transformed into a dehydrated form and by calcination at 600°C the specific surface area of granules increased from 7.50 to 53.45m2/g. The granules were soaked in a 500g/lit solution of urea, where they adsorbed about 10wt.% urea. The dried urea-loaded granules were placed in water where the release of urea was measured by UV-vis spectrophotometry. Finally, different portions of urea-loaded granules were evaluated as fertilizer in the growing bed of corn plant where the height and the stem diameter of samples were compared with a control sample as well as a sample fertilized by urea directly. The results showed that by using the loaded granules, the urea consumption can be reduced by 50%.
Sa. Benkacem, K. Boudeghdegh, F. Zehani, Y. Belhocine,
Volume 17, Issue 2 (6-2020)
Abstract
This paper focuses on the effect of ZrSiO4/ZnO ratio on the properties of the glaze to be used on ceramic sanitary-ware. Structural and morphological characterization of these glazed ceramics were identified by XRD, SEM, FTIR and Raman Spectroscopy. Furthermore, thermal properties were determined by DTA and TG techniques. Besides, flexural strength, Vickers Microhardness, whiteness and chemical resistance were investigated experimentally. XRD analysis showed that the zircon and quartz were the crystalline phases, zircon was also precipitated into the glaze layer during firing. It was found that an increase of the ZrSiO4/ZnO ratio part weights from 3.85 to 67, causes an increase in the zircon crystallite particle size from 203.90 to 288.86 Å. From DTA, it was observed that by increasing ZrSiO4/ZnO ratio, the crystallization temperature of zircon decreases. The glaze exhibits the highest whiteness value when the ratio of ZrSiO4/ZnO becomes 12.60.
P. Shahsavari, B. Eftekhari Yekta, V. Marghussian,
Volume 17, Issue 3 (9-2020)
Abstract
Strong glass-ceramic foams with a compressive strength of 20 MPa were prepared by adding various amounts of Fe2O3 to a soda lime-based glass composition, and SiC as a foaming agent. The foams were prepared by firing the compacted samples in the range of 750–950°C for different soaking times. The crystallization behavior of the samples was investigated by Simultaneous Thermal Analysis (STA), Scanning Electron Microscope, and X-Ray Diffractometer (XRD). Based on the results, solid solutions of pyroxene groups were crystallized by the surface mechanism, between 730˚C and 900˚C during the firing of the specimens, and their amounts increases with increasing of the added iron oxide. Besides, we found that Fe2O3 neither acts as a nucleant for pyroxene nor as an oxidizer for SiC. The results also showed that the compressive strength as well as the crystallization behavior of the foams was influenced by the presence of the SiC particles.
Amir Hosein Paryab, Sorosh Abdollahi, Rashid Khalilifard, Hamid Reza Madaah Hosseini,
Volume 18, Issue 1 (3-2021)
Abstract
As an alternative to conventional fertilizers, e.g. NPK (the Nitrogen-Phosphorous-Potassium containing chemical fertilizers) which release their nutrients in a short period of time, due to high solubility in irrigation water, glass fertilizers are ideal as they release macro- and micronutrients for crops and plant nourishment. Also, despite conventional ones, they have no ground-water pollution. In the present study, glass fertilizers were synthesized via Polymer-Derived Ceramics (PDC) method. Despite the melt-casting procedure, PDC needs lower temperatures in heat treatment. The precursors consist of poly-siloxane and active fillers. Thus, thanks to gaseous release during heat treatment of the present active fillers, i.e. Ca(OH)2, MgCO3, and Al(OH)3, a porous microstructure can be generated. In order to manipulate the pore size and specific surface area, fractions of active fillers were used as calcined. The experiments showed that upon increase of non-calcined active fillers, the specific surface area and the amount of porosity was increased due to more gaseous release during heat treatment. Thus, affected by microstructure, the release rate of macro and micro-elements was higher in the sample containing non-calcined active fillers, in comparison to other samples. Additionally, the porous samples were able to be loaded by extra nutrients containing Nitrogen, like KNO3.
Amirhosein Paryab, Toktam Godary, Sorosh Abdollahi, Mohsen Anousheh, Adrine Malek Khachatourian,
Volume 18, Issue 3 (9-2021)
Abstract
Silicon oxycarbide (SiOC) materials derived from silicone attracted great attention for their superior high-temperature behavior. In the present study, Si(Ti)OC and Si(Ti,Al)OC nanocomposites, in which alkoxide precursors were used with the main silicone precursor, have been compared with SiOC material. Although in SiOC, C was bonded with Si in a carbon-rich SiOC phase, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that TiC was the preferred state for C atoms upon adding Ti into the system. This claim was also substantiated by Raman spectroscopy, where adding Ti into the system lowered the intensity of the D band, indicating the high affinity of C to form crystalline TiC. In the Si(Ti,Al)OC nanocomposites synthesized by adding AlCl3 into the Si(Ti)OC system, mullite nanocrystals formed a superlattice structure with TiC. UV-vis spectra of the nanocomposites showed Si(Ti,Al)OC with mullite-TiC superlattice had a larger bandgap compared with Si(Ti)OC with only TiC nanocrystals.
Hamid Ansari, Saeed Banaeifar, Reza Tavangar, Alireza Khavandi, Soheil Mahdavi,
Volume 19, Issue 3 (9-2022)
Abstract
The present study aimed to assess the effect of replacing copper as a multi-functional ingredient in the brake pad material with potassium titanate platelet (PTP) and a particular type of ceramic fiber (CF) copper-free composite. Chase dynamometer tests were conducted to compare a brake padchr('39')s tribological behavior when PTP and CF are added to the composition with that of the copper-bearing pad. The results concluded that PTP and CF demonstrated promising outcomes such as a stable coefficient of friction (COF), lower wear rate, and better heat resistance in copper-free friction composite. Scanning electron microscope (SEM/EDS) analysis was conducted to investigate the role of main elements such as Ti, Fe, K, O, and C on the formation of contact plateaus (CPs) upon the worn surface of friction composites. PTP maintained both continuous contact and smooth friction braking application of a brake pad. The uniform distribution of Ti on the wear track on the disc worn surface depicts the role of PTPs on stabilizing the friction film formation and eventually on the stability of COF.
Hussein Ali Jan Miran, Zainab Naji Abdullah, Mohammednoor Altarawneh, M Mahbubur Rahman, Auday Tariq Al-Bayati, Ebtisam M-T. Salman,
Volume 20, Issue 1 (3-2023)
Abstract
This contribution evaluates the influence of Cr doping on the ground state properties of SrTiO3 Perovskite using GGA-PBE approximation. Results of the simulated model infer agreement with the previously published literature. The modification of electronic structure and optical properties due to Cr3+ doping levels in SrTiO3 has been investigated. Structural parameters infer that Cr3+ doping alters the electronic structures of SrTiO3 by shifting the conduction band through lower energies for the Sr and Ti sites. Substituting Ti site by Cr3+ results the energy gap in being eliminated revealing a new electrical case of conducting material for the system. Furthermore, it has been noticed that Cr doping either at Sr or Ti positions could effectively develop the SrTiO3 dielectric constant properties. Consequently, Cr3+ is an effective dopant due to enhancing the optical absorption properties, thus opening up new prospects for optoelectronic applications.
Parisa Rastgoo Oskoui, Mohammad Rezvani, Abbas Kianvash,
Volume 20, Issue 2 (6-2023)
Abstract
Abstract
The effect of different heat-treatment temperatures on the magnetic, crystallization, and structural properties of 20SiO2.50FeO.30CaO (mol%) glass ceramics was studied. The initial glass was synthesized by the sol-gel method at 25℃ with a precursors to solvent ratio of 1/5. After aging the resulted gel for 24 h at room temperature, it was dried in an electric dryer at 110 ℃ . By heat treatment at different temperatures, different phases such as magnetite, maghemite, and hematite were crystallized in the glass. The maximum stability temperature of magnetite and maghemite were 360℃ and 440℃ respectively. By increasing the heat treatment temperature to higher than 440℃ , the oxidation of maghemite to hematite was occureds. The highest magnetization amount (1.9 emu/g) belonged to sample heat treated at 680℃ . By increasing the heat treatment temperature to 840℃ , the magnetization decreased to 0.8 emu/g, due to the oxidation of maghemite. By increasing the heat treatment temperature from 440℃ to 680℃ , crystalline size of maghemite was increased from 40 to 200 nm. By forther increment of temperature to 840℃ , the size of maghemite crystals decreased to 17nm, due to the oxidation of maghemite to hematite.
Abstract
The effect of different heat-treatment temperatures on the magnetic, crystallization, and structural properties of 20SiO2.50FeO.30CaO (mol%) glass ceramics was studied. The initial glass was synthesized by the sol-gel method at 25℃ with a precursors to solvent ratio of 1/5. After aging the resulted gel for 24 h at room temperature, it was dried in an electric dryer at 110 ℃ . By heat treatment at different temperatures, different phases such as magnetite, maghemite, and hematite were crystallized in the glass. The maximum stability temperature of magnetite and maghemite were 360℃ and 440℃ respectively. By increasing the heat treatment temperature to higher than 440℃ , the oxidation of maghemite to hematite was occureds. The highest magnetization amount (1.9 emu/g) belonged to sample heat treated at 680℃ . By increasing the heat treatment temperature to 840℃ , the magnetization decreased to 0.8 emu/g, due to the oxidation of maghemite. By increasing the heat treatment temperature from 440℃ to 680℃ , crystalline size of maghemite was increased from 40 to 200 nm. By forther increment of temperature to 840℃ , the size of maghemite crystals decreased to 17nm, due to the oxidation of maghemite to hematite.
Zahra Shamohammadi Ghahsareh, Sara Banijamali, Alireza Aghaei,
Volume 20, Issue 2 (6-2023)
Abstract
Various analysis techniques were used to investigate the effects of P2O5 on the crystallization, mechanical features, and chemical resistance of canasite-based glass-ceramics. The results showed that canasite-type crystals were the primary crystalline phase in the examined glass-ceramics subjected to the two-step heat treatment, while fluorapatite was the secondary crystalline phase in some specimens. The microstructural observations by field emission electron microscope indicated that the randomly oriented interlocked blade-like canasite crystals decreased with an increase in the P2O5 content of the parent glasses. Among the examined glass-ceramics, the Base-P2 composition (containing 2 weight ratios of P2O5 in the glass) showed the most promising mechanical features (flexural strength of 176 MPa and fracture toughness of 2.9 MPa.m1/2) and chemical resistance (solubility of 2568 µg/cm2). This glass-ceramic could be further considered as a core material for dental restorations.
Ahmed Hafedh Mohammed Mohammed, Khairul Anuar Bin Shariff, Mohamad Hafizi Abu Bakar,
Volume 20, Issue 4 (12-2023)
Abstract
The coated β-tricalcium phosphate (β-TCP) with dicalcium phosphate dihydrate (DCPD) has attracted much attention in the biomaterials field due to the increase in its osteoconductivity. Besides, the porous bioceramic scaffolds with controlled pore sizes are significant in stimulating bone-like cell activity. In this study, the effect of the setting-time process and acidic-calcium phosphate (CaP) concentrations on the fabrication and properties of porous DCPD/ β-TCP scaffolds were studied. Subsequently, the specimens were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), compression strength and Fourier transforms infrared (FTIR). The study results revealed that the porous DCPD/ β-TCP scaffolds with macro- and micropore sizes were successfully obtained after the 300-600 µm of porous β-TCP granules were exposed to an acidic-CaP solution. Furthermore, the setting-time process and acidic-CaP concentrations increased the DCPD interlocking between granules, and the mechanical strengths of scaffolds increased up to 0.5 MPa. Meanwhile, the porosity levels were changed based on the formation of DCPD crystals. This study was expected to provide novel insights to researchers in the field of bioceramics through its investigation on the creation of porous DCPD/ β-TCP scaffolds.
Zainab Dhyaa Fawzy, Saja Ali Muhsin, Taha Hassan Abood,
Volume 21, Issue 0 (3-2024)
Abstract
Ceramics in dentistry have been mainly recommended from a cosmetic perspective. Yet, the hardness behaviour may limit the application in many cases. Although amber glass is used for medications and chemicals, no studies focus on using amber glass for dental purposes as an additive material. This study aims to investigate the dark amber glass behaviour as a new additive material for dental ceramics. The amber glass powder was prepared using the ball mill technique. For the amber glass powder characterization, the SEM/EDX, particle size, DSC, Ion release, and XRD analysis were tested compared to VITA Lumex® AC ceramic. In addition, the Vickers hardness test was applied for ceramic and ceramic amber with an addition of 0.01g, 0.03g, and 0.05g amber glass powder following the DIN EN ISO 6872/ 2019. Statistically, the ANOVA (post hoc- Tukey) test was used for hardness testing analysis at a significant P-value of (P≤0.05). The results show that the amber glass behaviour and composition elements seem similar to VITA ceramics. The addition of amber glass powder to ceramic shows an increase in the HV hardness of specimens. Overall, it was concluded that the amber glass powder could be a promising material for ceramics to use as an additive powder.
Ahad Saeidi, Sara Banijamali, Mojgan Heydari,
Volume 21, Issue 2 (6-2024)
Abstract
This study explores the fabrication, structural analysis, and cytocompatibility of cobalt-doped bioactive glass scaffolds for potential applications in bone tissue engineering. A specific glass composition modified from Hench's original formulation was melted, quenched, and ground to an average particle size of 10 μm. The resulting amorphous powder underwent controlled sintering to form green bodies and was extensively characterized using simultaneous differential thermal analysis (DTA), Raman spectroscopy, and Fourier Transform Infrared analysis (FTIR). After mixing with a resin and a dispersant, the composite was used in digital light processing (DLP) 3D printing to construct scaffolds with interconnected macropores. Thermal post-treatment of 3D printed scaffolds, including debinding (Removing the binder that used for shaping) and sintering, was optimized based on thermogravimetric analysis (TG) and the microstructure was examined using FE-SEM and XRD. In vitro bioactivity was assessed by immersion in simulated body fluid (SBF), while cytocompatibility with MC3T3 cells was evaluated through SEM following a series of ethanol dehydrations. The study validates the fabrication of bioactive glass scaffolds with recognized structural and morphological properties, establishing the effects of cobalt doping on glass behavior and its implications for tissue engineering scaffolds. Results show, Low cobalt levels modify the glass network and reduce its Tg to 529 oC, while higher concentrations enhance the structure in point of its connectivity. XRD results shows all prepared glasses are amorphous nature, and DTA suggests a concentration-dependent Tg relationship. Spectroscopy indicates potential Si-O-Co bonding and effects on SiO2 polymerization. Cobalt's nucleating role promotes crystalline phases, enhancing bioactivity seen in rapid CHA layer formation in SBF, advancing the prospects for bone tissue engineering materials.
Mahnaz Dashti, Saeid Baghshahi, Arman Sedghi, Hoda Nourmohammadi,
Volume 21, Issue 3 (9-2024)
Abstract
Abstract
The power line insulators are permanently exposed to various environmental pollutants such as dust and fine particles. This may lead to flashovers and therefore widespread power blackouts and heavy economic damage. One way to overcome this problem is to make the insulator surface superhydrophobic. In this research, the superhydrophobic properties of the insulators were improved by applying room-temperature cured composite coatings consisting of epoxy and hydrophobic nano-silica particles. Either octadecyl trichlorosilane (ODTS) or hexamethyldisilazane (HMDS) was used to coat the silica nanoparticles and make them hydrophobic. Then, the hydrophobic silica was added to a mixture of epoxy resin and hardener. The suspension was applied on the surfaces of a commercial porcelain insulator and cold cured at ambient temperature. The coating increased the water contact angle from 50° to 149°. Even after 244 h exposure to the UV light, the samples preserved their hydrophobic properties. The adhesion of the coating was rated as 4B according to the ASTM D3359 standard. The coating decreased the leakage current by 40% and increased the breakdown voltage by 86% compared to the uncoated sample and showed promise for making power line insulators self-cleaning.
Ahabboud Malika, Gouitaa Najwa, Ahjyaje Fatimazahra, Lamcharfi Taj-Dine, Abdi Farid, Haddad Mustapha,
Volume 21, Issue 4 (12-2024)
Abstract
This paper reports the preparation and characterization of (1-x) PbZr0.52Ti0.48O3 -xBiFeO3 (1-x)PZTxBFO) (x= 0.00, 0.15, 0.30, 0.45, 0.60 and 1.00) multiferroic ceramics which were prepared by a sol-gel method for PZT and hydrothermal reaction process for BFO. The perovskite structure of the composite system was confirmed by X-ray diffraction and Raman spectroscopy, while the composite microstructure w:as char:acterized by scanning electron microscopy. XRD results and Rietveld analysis for the (1-x)PZT-xBFO composites confirm the coexistence of these three phases; rhombohedral (R3m) and tetragonal phases (P4mm) for pure PZT and only the rhombohedral phase (R3c) for pure BFO. Raman spectroscopy of the (1-x)PZT-xBFO composites shows two clear bands around 150 and 180 cm-1. When the BFO content increases, the intensities of Raman modes are decreased. The SEM results suggested a formation of agglomerate and form into large complex clusters as BFO increased and a higher grain size was obtained for the BFO sample compared with the other composites. The EDS spectra of our pellets show that all the characteristic lines of the chemical elements Pb, Zr, Ti, and O and Bi, Fe, and O are present for the PZT and BFO materials respectively. The temperature-dependent dielectric constant shows different behavior dependent on BFO content. Indeed, the dielectric properties are found to be improved with an increase in dopant concentration of BFO in PZT, and novel dielectric behavior, resonance, and antiresonance, were obtained.
Zahra Ghoreishy, Bijan Eftekhari Yekta,
Volume 21, Issue 4 (12-2024)
Abstract
ZrO2 is commonly incorporated into ceramic glass substrates to enhance radiopacity, mechanical strength, and chemical durability. Experience has shown that the crystallization of tetragonal zirconia in glass will have a greater effect on the mechanical properties of ceramic glass. To achieve optimal properties in zirconia, stabilizing oxides are often added to enhance its structural and mechanical qualities. In this research, in order to stabilize the tetragonal phase of zirconia, MgO and CeO2 were added to the glass ceramic composition of the Li2O-SiO2-ZrO2 system and the desired dental substrate was synthesized through the sinter process. The behavior of sintering and crystallization of basic and optimized glass was investigated using HSM and DTA thermal analysis, respectively. The results showed that the optimal sinter temperature, heat press and heat treatment are equal to 730°C, 900°C and 825°C, respectively. Then, in order to determine the crystallization behavior of the prepared samples, X-ray diffraction and microstructure images were used. The results also showed that the presence of the main Li2ZrSi6O15 phase crystallizes at a temperature of 825°C in the base sample and the sample containing ceria. Also, due to early formation of MgSiO3 crystals, magnesia prevents sintering and formation of Li2ZrSi6O15 phase and stability of tetragonal zirconia phase. In the sample containing ceria, during crystallization, ZrO2 entered its crystal structure and led to the stability of the tetragonal zirconia phase at room temperature.
