نشریه علم و مهندسی سرامیک
سال نهم شماره 2 (تابستان 1399)

In the present research work, (60-x)V2O5-xNiO-40TeO2 amorphous bulk compositions with different molar percentages of 0≤x≤20 mol%, were prepared by well-known  rapid melt-quenching method. Differential scanning calorimetry (DSC) at different heating rates (φ) was used to thermal analyze and to obtain more insight in to the thermal stability, glass forming tendency and so calorimetric characteristics of the present glasses. The characteristic temperatures such as glass transition temperature (Tg), the temperature corresponding to the onset of crystallization (Tx) and also the crystallization temperature (TCr) were obtained at different heating rates, to evaluate the key kinetic parameter of activation energy of crystallization (Ec) by using Ozawa and Kissinger methods. Generally, results of this work show that the glass with x=10 has the highest thermal stability and glass forming tendency and so has very good resistance against thermal shocks; for  the understudied samples, one can observe the decreasing trend of crystallization activation energy with increase of NiO content, which can be resulted by increasing of non-bridging oxygenchr('39')s (NBOs).

In the present work, the effect of sintering parameters including sintering temperature, soaking time, and heating rate on densification, microstructure, and dielectrical properties of bismuth titanate (Bi4Ti3O12) ceramics were investigated. Bismuth titanate was synthesized by the solid state method and titanium oxide and bismuth oxide used as raw materials. X-ray diffraction (XRD) indicated, pyrocholore phase of Bi2Ti2O7 as secondary phase was appeared at sintering temperature higher than 1075 °C due to bismuth loss in bismuth titanate. The maximum relative density of 97% with plate-like grains was acquired in optimized sintering condition for samples sintered at 1075°C for 1 h with heating rate of 5 °C/min. The results of the dielectric properties showed that the dielectric constant and the dielectric loss of bismuth titanate ceramic are very sensitive to relative density.  With increase of relative density of samples, the dielectric constant increased linearly and the dielectric loss decreased exponentially. The best dielectric properties with maximum dielectric constant (290) and minimum dielectric loss (0.013) were obtained for samples sintered in optimal sintering conditions.

Austenitic stainless steels are high performance steels that have various applications in solid oxide fuel cells and boiler tubes under high temperature operating conditions. The Cr2O3 oxide layer formed on the steel surface becomes unstable at high temperatures and reduces the oxidation resistance of the steel. Therefore, protection of these steels at high temperatures is essential. Therefore, one of the best effective ways to extend the life of these components against oxidation is by applying protective coatings. In this research, Ni-Co-CeO2-ZrO2 composite coating was created by direct electrodeposition on the surface of AISI 304 austenitic stainless steel. In order to obtain proper coating, the effect of current density, pH and concentration of ZrO2 in the bath was investigated. To create the optimum deposition, the bath parameters were investigated. Influence of ZrO2 content (5, 10 and 25 g/L), current density (15, 20, 25 and 30 mA/cm-2) and pH (3, 3.5, 4 and 4.5) on the deposition amount of ceramic particles and microstructure of the coating has been investigated. Scanning electron microscopy (SEM) and EDX analysis were used to determine the morphology. The results showed that with increasing ZrO2, the amount of ZrO2 deposition increased and the amount of CeO2 deposition decreased. Also, with increasing current density and pH, the amount of ZrO2 and CeO2 particles decreased.

Study on the production technology in ancient glass artefacts is one of the interesting subject in the field of archaeological sciences. The aim of this study is to identify the chemical composition and production technology in the glass objects discovered form the underground hand-made architectural complex of Arzanfood, near Hamedan, in western Iran. These objects are including some broken pieces of glass vessels, glass bracelets and one piece of a glassy material without specific shape. To characterize the technology of glass production in the glass objects from Arzanfood, 12 samples from broken vessels, bracelets and the glass piece without specific shape were analyzed by analytical instruments. Based on the archaeological studies in the site, these objects are dated to Sasanian and middle Islamic periods. For chemical analysis, the samples were analyzed by inductively coupled plasma- mass spectroscopy (ICP-MS) method to measure major, minor and trace constituents, and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) to observe the microstructural features. The results show that soda-lime glass (soda-lime-silica glass with plant ash) has been used to make the glass objects. Only in the no-shape piece a completely different composition is visible including different content of major and minor constituents in comparison with other glass objects. The microstructure of samples represents two different types of glass matrix including homogenous glass matrix and glass matrix with significant amounts of high-lead and high-tin phases. Presence of lead and tin phases in the microstructure of these objects is due to use lead and tin compounds as opacifier in the composition of glass material used in manufacturing the objects.

Flash sintering as a new sintering method for sintering of ceramic materials has been studied and effect of various parameter such as flash current density, time of flash and contact paste on properties of flash sintered 8YSZ samples has been investigated. Results showed it is possible to achieve high density in shorter time and lower temperature than conventional sintering methods. Samples could be sintered more than 95% theoretical density by electrical field 100V/cm, current density 160mA/mm2, and flash time of 30 sec at 800° С. The same density could be achieved by electric furnace and conventional sintering methods at 1400 °С for 4 hours. Results showed current density and temperature has positive effect on density. Also samples with LSM paste in lower current density had higher density relative to Pt paste ones.

In this study, yellow ceramic nano pigments based on ZrO2 (zirconium oxide) were synthesized by solid state method using different value of Fe2O3 as dopant. The pigments were dispersed in solvent by a planetary ball mill and then the inks were printed on the ceramic surface using screen printing method. The samples were analyzed using scanning electron microscopy (SEM), X-ray diffraction spectrum (XRD) and CIE Lab Colorimetric Analysis. Results showed that by changing the amount of Fe2O3 dopant from 0.07 to 0.2 gr, the average particle size changed from 170 to134 nm. The colorimetric results revealed that after increasing Fe2O3 dopant, the amount of a* parameter increased from 1.21 to 6.72, b* from 34.72 to 47.53, while L* parameter (lightness) reduced. After printing of pigments on the ceramic surface, the average particle size of each sample decreased; also, the L* (lightness) and a* (red) increased while b* (yellow) decreased.

Effect of CaCO3 on carbothermic formation of hexagonal boron nitride (h-BN) was investigated. B2O3–C mixtures containing CaCO3 additive were reacted at 1500   for 120 min in nitrogen atmosphere. Formed phases in the reaction products were determined by powder-XRD analyses, and amounts of the constituents were determined by chemical analyses. Particle size and morphology of the formed h-BN powders were examined by SEM. It was found that the use of resin instead of carbon black increased the amount of boron nitride formed and decrease grain size of h-BN significantly. The average particle size with black carbon was about 200–350 nm, On the other hand, the average particle size with resin is about 90-170 nm. In this paper, the amount of boron oxide was also variable, which increased as the amount of boron nitride produced increased and then remained almost constant.

Archaeological rescue project of the Silveh Dam was carried out by Iranian Center for Archaeological Research (ICAR) (952141/00/3937 – 1395/12/23) permission during about four monthschr('39') field activities. Tepe Silveh or as villager named Tepe Sheikh Esmail Silveh (N: 36° 48chr('39') 099chr('39')chr('39') – E: 45° 05chr('39') 937chr('39')chr('39') – 1567m asl) is located exactly 100 m north of the Silveh village. Tepe Silveh is located in the center of intermountain river valley on the northern margin of the village, which has already been demolished and abandoned. Main important assemblage of findings belong to painted buff and orange and as well as few grey/black pottery that introduced and reported by Tepe Silveh and Tepe Hasanlu and some other surveyed sites. No Archaeometrical and chemical-mineralogical characterization have been done yet on pottery assemplages.
Hence, 51 pottery specimens was sampled from different period and layers of the Tepe Silveh belong to Late Chalcolithic to Early Bronze Age pottery tradition of black/gray burnished Kura-Araxes culture and as well as painted buff and red pottery traditions of Early Bronze Age of Hasanlu VII (Hasan Ali Ware) and Ninevi 5 to address such issues as its geological source, manufacturing techniques, firing and kiln conditions, local or foreign provenience, determination of sharing and segregation between different groups of pottery. To determine the crystalline constituents, different mineralo-chemical investigations were undertaken. The major phase compositions of the pottery assemblages were determined using X-ray diffraction (XRD), and for thermography DTA were used. Also, the thin-section of the pottery was analyzed by optical microscopy techniques so as to petrographic identification of the minerals. The result of phase identification and petrographic analysis showed that the studied pottery is similar in terms of composition and mineralogy but are completely different in terms of morphology, baking technique and color as well as kiln conditions. According to the similarity of the main structural combination and characterization of black – gray pottery assemblage with the geological structure of the region it should be suggested that this type of pottery produced locally in the Piranshahr or close adjacent region that is not very far from the site that in terms of geological structure and charectrization have similar compounds with Tepe Silveh Pottery. Also, due to the complete match of thermal analysis with the results of petrography and X-ray diffraction analysis, the baking and firing temperature in all samples can be estimated at 850 °.