Porcelain Bodies Research Articles

Effects of the crystal phase and microstructure of pottery bodies on the transmission characteristics of terahertz waves

ABSTRACT We recently reported that the terahertz (THz)-wave characteristics of pottery bodies varied significantly with firing temperature. This suggested the feasibility of conducting nondestructive inspection of the sinterability and manufacturing-process management of ceramics by THz-wave analysis. However, it is not clear why the THz-wave characteristics of ceramics change with firing temperature. In this study, we evaluated the THz-wave transmission properties of low-temperature-sintered porcelain bodies fired at various temperatures using THz time-domain spectroscopy and investigated the relationship between the crystal phase and microstructure. We found that the THz-wave transmittance increased with the dehydration of kaolinite and decreased with the formation of mullite and glass phases in the body. Also, as the firing temperature increased, the THz-wave transmittance of these bodies was affected by scattering due to the formation of pores. Additionally, the refractive index in the THz range showed a good correlation with the bulk density. We established that the firing-temperature dependence of the refractive index in the THz range was related to the crystal phase and microstructure.

Investigation of fluorescent lamp glass waste as a fluxing agent in porcelain bodies

In this research the effect of fluorescent lamp glass waste (FLGW) as a fluxing agent for preparing porcelain bodies has been investigated. Three different standard mixtures of porcelain bodies were prepared which composed of (kaolin, flint and potash feldspar). The FLGW is added to the porcelain samples at different ratios of (0, 5 and 10) wt.% as a partial replacement of potash feldspar. The samples were prepared using semi-dry process and then sintered at different temperatures ranged of (925–1250)°C. Sintering behavior, physical and mechanical properties of the prepared porcelain bodies were measured. The results showed the possibility of using the FLGW as a fluxing agent for the production of porcelain bodies. Increasing of sintering temperature leads to enhance the physical and mechanical properties of porcelain bodies. Addition of FLGW as a partial replacement of potash feldspar in the porcelain composition batch has beneficial effect on lowering the sintering temperature of porcelain bodies, consequently of accelerating the densification rates. The physical and mechanical properties of porcelain bodies reduced when added of high amount of FLGW up to 10 wt%. This is related to the composition of FLGW that contents of different materials with the presence of impurities in considerable amounts.

Colour and composition characteristics of beige-glazed porcelain from Jingdezhen Imperial Kiln, early and middle Qing Dynasty (18th century)

The Jingdezhen Imperial Kiln made unprecedented achievements in the firing of colour glazed porcelain during the Qing Dynasty (1636–1912). Among these, beige-glazed porcelain became an imperial porcelain variety reserved for the exclusive use of the imperial household. To reveal details of the manufacturing process, Energy Dispersive X-ray Fluorescence (EDXRF) and spectrophotometry, combined with the records of ancient Chinese documents were used to analyse samples of beige-glazed porcelain fired at the Jingdezhen Imperial Kiln in the early and middle Qing Dynasty (18th century) and unearthed from the Nandaku area of the Forbidden City. The results show that the colour of beige glaze in the Qing Dynasty was similar to that in the Song Dynasty (960–1279), which is consistent with ancient literature records reflecting the former's imitation of ‘Beige Song Glaze’. The beige-glazed porcelain body is made of a binary formula of porcelain stone and kaolin clay, in a ratio between 5:5 and 4:6. Based on the glaze layer formula of purple-gold imperial porcelain, the beige glaze layer was fired by innovatively adjusting the ratio of glaze stone, glaze ash and purple-gold clay. The imitation of ‘beige Song glaze’ and the innovation of purple-gold glaze reflected the exacting production and high technology of the Jingdezhen Imperial Kiln in the Qing Dynasty.

Differences in phase, microstructural, and electrical characteristics of quartz-substituted alumina porcelain insulator

In the present study, total quartz content (30 wt%) of a standard porcelain body was progressively substituted with two different kinds of aluminas (active alumina and calcined alumina) keeping active alumina constant at 5 wt% and varying calcined alumina content to the extent of 5–25 wt%. The alumina incorporated compositions (AP1 to AP7), along with the standard quartz containing porcelain body (SP0), were processed following common ceramic processing techniques. Two types of forming techniques were used to make samples, namely extrusion of plastic mass to get cylinder of desired dimensions and the other one was hydraulic compaction to produce rectangular bars. The extruded and compacted samples were properly dried and then heated in an electrically operated furnace in the temperature range of 1170–1260 °C. The fully densified samples heated at 1260 °C were subjected to various tests, namely phase identification by X-ray diffraction (XRD) pattern studies; scanning electron microscopic (SEM) analysis; and measurement for electrical properties such as dielectric strength (kV/mm), dielectric loss (tanδ), electrical resistivity (ohm-cm), and dielectric constant to confirm suitability of the samples for application in high-tension power transmission system. The results revealed that the body AP6, wherein 25 wt% quartz was substituted by 5 wt% active alumina and 20 wt% calcined alumina and heated at 1260 °C, may be considered the most suitable sample for porcelain insulator.

The Replacement of Seashells with Calcite in White Ceramic Glaze Preparation

In this study, the effect of seashell utilization as a replacement for calcite on the surface features and optical properties of white ceramic glazes was investigated. As received seashells collected from Black Sea beaches of Samsun, Turkey and purified seashells at 700°C for 1 h were used as calcite replacement by 15 wt.%. Seashell powders were incorporated to white glaze compositions which are applied on the surface of different fired clay bodies such as red clay, chamotte, white and porcelain by dipping technique. Next, the glazed green bodies were sintered at 1100ºC for 8 h. Following to TG-DTA, heating microscope, XRD and optical analysis, the obtained results exhibited that as received seashell powder (SP-1) was composed of calcite (CaCO3), whereas purified seashell powder (SP-2) comprised aragonite (CaCO3) and calcium oxide (CaO). The iron (hematite) content in red clay and the impurities in seashells composition caused specks and crawlings on the surface of glazed red clay bodies and of some glazes containing seashell, respectively. In generally, the higher CaO content in SP-2 enhanced gloss (60°) values, and whiteness values of most glazed surfaces were closed to each other. The color of chamotte bodies increased redness-greenness values. The variations in optical parameters were mainly associated with the difference in body compositions. SP-1 contained glaze, applied on porcelain body, was selected as optimal because that had 33 gloss value, high whiteness (87) and no surface defect. Therefore, the utilization of as received seashells by 15 wt.% as calcite replacement allows eco-friendly and cost-effective production of white ceramic glazes without any additional heat treatment.

Effect of Alumina (Al<sub>2</sub>O<sub>3</sub>) to the Properties of Whiteware Porcelain

The effect of Al2O3 to the properties of whiteware porcelain such as water absorption, bulk density, flexural strength and crystalline phases were studied systematically. The result shows that the addition of alumina at maximum 5 wt.% in porcelain bodies increased the flexural strength of the fired bodies which can reach 55.5 MPa, 30% higher than 0.0% alumina content. However, slight decrease in the other physical and mechanical properties was observed with Al2O3 addition higher than 5 wt.%, which is believed to be due to increased corundum phase compared to mullite phase in porcelain body.

An on-site Raman and pXRF study of Joseph Coteau and Philippe Parpette’s jewelled porcelain: a summit of ceramic art

Abstract Gilt-decorated porcelains of the French enamellists Joseph Coteau and Philippe Parpette, unifying metal and ceramic enamel techniques had been produced for a short time period, between ∼1770 to 1800 AD. However, this type of production was limited and poorly documented. Their enamelled decorations consist of lead-based transparent and opaque enamels coating gold foils fired on the porcelain glaze. Rare items had been produced at different factories (Sevres Royal Factory, Comte d’Artois Factory) and it is reported that some copies had been made during the 19th century. We present here the first (non-invasive) Raman study of four cups and two pairs of vases (also analysed by pXRF) belonging to the productions from these factories. The decors made of enamel on gold foil (paillon in French) were applied both on soft-paste and hard-paste porcelain body. The bonding between the gold foil and the glaze was found to be obtained by addition of arsenic and perhaps some other fluxes (boron, bismuth?). Differences were identified in the glazing/enamelling technology. The use of cassiterite opacifier seems to be characteristic of Coteau’s technique.

FARKLI KENAR BİTİM VE ALT YAPI DİZAYNLARININ ÇEŞİTLİ ZİRKONYUM ALT YAPILAR ÜZERİNDEKİ VENER PORSELENİN KIRILMA DİRENCİNE ETKİSİNİN İNCELENMESİ

Amaç: Bu çalışmada, kenar bitim ve alt yapı şekillerinin çeşitli zirkonyum alt yapılar üzerindeki vener porselenlerinin kırılma direncine etkisi in vitro olarak incelenmiştir. Gereç ve Yöntem: Örneklerin elde edileceği kesilmiş üst 1. küçük azı dişini temsil eden güdükler; 1. Güdük; 6 mm kuron boyu ve 6 0 taper açısında 1 mm shoulder basamak ile anatomik oklüzal yüzeyli, 2. Güdük; 6 mm kuron boyu ve 6 0 taper açısında 1 mm chamfer basamak ile anatomik oklüzal yüzeyli, 3. Güdük; 6 mm kuron boyu ve 6 0 taper açısında, 1 mm shoulder basamak ile düz oklüzal yüzeyli, 4. Güdük; 6 mm kuron boyu ve 6 0 taper açısında 1 mm chamfer basamak ile düz oklüzal yüzeyli olarak standardizasyonun sağlanması amacıyla CNC torna tezgahında hazırlanmıştır. Güdüklerden alınan ölçülerden 60 adet epoksi rezin güdük elde edilmiştir. Zirkonyum alt yapılar farklı yöntemlerle hazırlandıktan sonra üst yapı porseleni uygulanarak kuronlar tamamlanmıştır. Kuronlar epoksi rezin güdükler üzerine simante edildikten sonra vener porselenlerinin kırılma dirençleri Universal test cihazında saptanmıştır. Bulgular: Veriler üç yönlü varyans analizi (ANOVA) ile değerlendirilmiştir. Kenar bitim şekli, alt yapı şekli ve materyallerin, materyaller ile alt yapı şekli, materyaller ile kenar bitim şekli arasındaki etkileşimin anlamlı olduğu, kenar bitim şekli ile alt yapı şekli, materyaller ile alt yapı şekli ve kenar bitim şekli arasındaki etkileşimlerin ise anlamlı olmadığı istatistiksel olarak tespit edilmiştir. Sonuç: En yüksek vener porselen kırılma direnci değerlerinin alt yapısı anatomik şekilde hazırlanan chamfer basamaklı White Peaks kuronlarda, en düşük kırılma direnci değerlerinin ise alt yapısı düz şekilde hazırlanan chamfer basamaklı Lava kuronlarda olduğu görülmüştür. Anahtar Kelimeler: Alt yapı şekli, kenar bitim şekli, kırılma direnci, zirkonyum alt yapılar. Effect of different marginal finish lines and coping designs on the fracture resistance of veneering porcelain on various zirconia frameworks ABSTRACT Aim: In this in vitro study, the effect of finish line and coping design on the fracture resistance of veneer porcelains on the zirconia frameworks prepared through various methods was analyzed. Material and Methods: To standardization, the dies representing the upper first premolar tooth were prepared in the CNC turning machine as: the first die; with a 6 mm crown length and at 6 0 taper angle, having an anatomic occlusal surface with a 1 mm shoulder line, the second die; with a 6 mm crown length and at 6 0 taper angle, having an anatomic occlusal surface with a 1 mm chamfer line, the third die; with a 6 mm crown length and at 6 0 taper angle, having a flat occlusal surface with a 1 mm shoulder line, and the fourth die; with a 6 mm crown length and at 6 0 taper angle, having a 1 mm chamfer line with a flat occlusal surface. 60 pieces of epoxy resin dies were obtained from the measurements taken from the dies. Zirconia frameworks had been prepared through different methods, then crowns were completed by applying the body porcelain. After cementation the crowns on the epoxy resin dies, the fracture resistance of veneer porcelains was measured by the Universal Test device. Results: The data were analyzed by three-way variance analysis (ANOVA). It was statistically determined that the interaction between the finish line, coping design and materials; and the materials and coping design, and the finish line and the materials. However; no significant interaction was observed between the finish line and coping design; and the materials, coping design and the finish line. Conclusion: The highest fracture resistance values of veneer porcelain was seen in chamfer line White Peaks crowns prepared anatomically, whereas the framework of the lowest fracture resistance values was seen in the chamfer line Lava crowns. Key Words: Coping design, finish lines, fracture resistance, zirconia frameworks

Failure Trends of High-Voltage Porcelain Insulators Depending on the Constituents of the Porcelain

The aging of porcelain insulators is responsible for the failure of power utilities. Porcelain insulators from different places in South Korea, possessing various aging times and years of installation, have been investigated to carry out lifetime statistics. These samples have a mass of 36,000 lbs and are operated at 154 kV. X-ray fluorescence (XRF) and scanning electron microscopy (SEM) were performed on the porcelain bodies of the samples collected. XRF and SEM revealed trends in the weight percentage of SiO2, Al2O3, and Fe2O3 in the porcelain bodies of the collected samples. The SiO2 and Fe2O3 weight percentage reduced to 8.93% and 73.17%, respectively, in sample C compared to A. However, the Al2O3 weight percentage increased to 16.23% in sample C compared to sample A. This change in weight percentage of SiO2, Fe2O3, and Al2O3 contributed toward enhancing the mechanical and electrical properties of the insulators. Mechanical load tests with electrical voltage (M&E), thermal and mechanical load tests (T&M), and hardness tests (HRB) were performed to evaluate these characteristics. Experiments revealed an increase of 90.9% in the inequality factor (K) in sample C compared to A. The impact of constituents of porcelain on the lifetime expectancy of a porcelain insulator was reported by implementing statistical strategies, such as the Weibull distribution.

Estimating the reduction of the firing temperature produced by the addition of energetic fluxes in porcelain tiles through the Fluegel’s model

Abstract Reducing the firing temperature and accelerating the densification process bring economic and environmental benefits. This study used Fluegel’s viscosity model, developed for glasses, to estimate the decrease of the firing temperature produced by the introduction of energetic fluxes in a porcelain body. The experimental results confirmed the prediction of the model, a 30 ºC reduction in the temperature, for the addition of wollastonite. However, for the addition of spodumene, the reduction was slightly higher than the predicted. These results suggested that Fluegel’s model may be used to estimate the effects of the introduction of energetic fluxes in porcelain tile compositions. However, the predictions should be seen as a general orientation. Among the limitations of the model were the extrapolation of limit values established by the model for the composition and, above all, the initial hypothesis that the chemical composition of the vitreous phase in porcelain tiles is constant.

Roles of talc-illite on phase transformation, vitrification and physical properties of a triaxial porcelain body

Roles of talc-illite on phase transformation, vitrification and physical properties of a triaxial porcelain body

Effect of different firing atmospheres on debonding strength of dental porcelain fused to commercially pure titanium.

An in vitro investigation was performed to evaluate the bonding characteristics of porcelain fused to metal (PFM)/commercially pure titanium (cp Ti, grade II) in three firing atmospheres of under vacuum and using two noble gases argon (Ar) and helium (He). Three groups of porcelain veneers firing under vacuum, Ar, and He were prepared to evaluate the bonding of porcelain fused to the cold-rolled cp Ti. The bond strength of PFM durability by a three-point bending test, phases, microhardness of cp Ti after firing processes, and fractures were measured and evaluated. Results show the microhardness of cp Ti in group of porcelain firing under He atmosphere was significantly lower than that of the two other groups, which were in vacuum and Ar (P < .05). X-ray diffraction showed the He group produced in relatively small amounts of TiO2 and TiO oxides than other groups but featured relatively high quantity of airhole defects in the porcelain body leading to the lowest bond strength. The Ar group presented the highest bond strength of comparing with the groups under vacuum and using He (P < .05). Although the firing processes in He could efficiently prevent the diffusion of oxygen into Ti, the porcelain-cp Ti bond strength using Ar protective atmosphere presented the advantage to achieve clinical requirement because porcelain firing under He revealed prominent voids and defects within the body of porcelain.

Structural characterization of mixed local material for a ceramic porcelain insulator

A novel type of ceramic porcelain insulator material was produced by mixing kaolin with zeolite. The composition was prepared by adding a controllable amount of kaolin ranging from 30 wt% to 100 wt% into the zeolite. Then a series of samples were sintered at 1200°C. The influence of the composition on the structural properties was studied in detail using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). The results show that the microstructure of porcelain body is characterized by the presence of elongated mullite grains. It was found also that the decrease of the kaolin content in the porcelain body leads to a decrease in the crystalline phase of mullite. The analysis of the structural properties of such ceramics indicates that zeolite could not be recommended as an appropriate material for manufacturing of high-voltage ceramic porcelain insulators by mixing it with kaolin.

Semi-Conducting Glazes Based on Cassiterite Crystalline Phase for Porcelain Insulators Applications: Phase Evolution, Microstructure and Electrical Properties

ABSTRACTTwo series of semi-conducting glazes based on cassiterite phase were prepared and characterized after application on electrical porcelain bodies. In one series, semi-conducting fraction of the final glazes was calcined, then added to the base glaze. In another series, semi-conducting fraction of the studied glazes was precipitated in-situ during firing. Morphology of cassiterite and its optimized content in the studied glazes were found as the most important parameter affecting electrical properties of final glazes. Maximum amount of cassiterite was achieved for the first series containing whole calcined semi-conducting constituent. Band gap of this glaze was found to be 2-2.6 eV. Surface resistance of insulator bodies coated with cassiterite based semi-conducting glazes was obtained 105-107 times more than that of the common glazes, indicating a uniform charge distribution and inhibition of partial discharge through surface of insulator.

Effect of Nepheline Syenite Additives on the Technological Behavior of Ceramics and Porcelain Stoneware Tiles

To study the effect of the Egyptian nepheline syenite raw materials on the sinterability of the ceramic tiles, four batches with concentrations of nepheline syenite (0, 5, 10 and 15%) were prepared. The four batches were ground, mixed, shaped, pressed and fired at temperatures from 1160 °C to 1260 °C. Some technological behaviors of the samples were measured in dry, green state and after firing at 1260 °C; including densfication parameters. Phase composition and microstructural studies refered that mullite was the newly crystallized phase after firing set in a glassy matrix enriched in alkalis. Technological properties of the fired batches revealed that the higher firing temperature and higher nepheline syenite contents produced larger amounts of glassy phase, and consequently bulk density and linear shrinkage increased, while apparent porosity and water adsorption as well as whiteness of fired batches decreased. It is concluded that nepheline syenite could be successfully used as flux in ceramic tiles, while it is not accepted in the production of porcelain bodies because of their coloration.

Influence of incorporation of fired porcelain scrap as partial replacement of quartz on properties of an electrical porcelain

Fired porcelain scrap has been recycled as filler to obtain a sustainable high voltage porcelain insulator. Quartz was progressively replaced by 5, 10, 15 and 25 wt% of porcelain scraps in a traditional siliceous porcelain composition. The replacement effect on sintered samples at 1250 °C under industrial scheduling using a manufacturing kiln was evaluated by measuring the linear shrinkage, bulk density, porosity, flexural strength, and microhardness. Phase analysis was carried out by X-ray diffraction and microstructural characteristics were studied using a scanning electronic microscope. The results showed that scrap containing samples reached bulk densities around 2.38 g/cm3 and a porosity percentage close to zero. The maximum flexural strength at both unglazed and glazed state was 67.5 MPa and 89.7 MPa, respectively for 5 wt% scrap containing samples. X-ray diffraction studies revealed higher mullite phase in scrap containing samples. Scanning electronic microscopy images of the polished and etched specimens show the presence of quartz grains and secondary mullite needles embedded in a feldspathic vitreous matrix. The properties displayed by the scrap containing samples are highly attractive, since they show similar and, in some cases, superior values in flexural strength, density, and porosity in comparison to those reported for traditional siliceous porcelain. The most outstanding result was found in the flexural resistance, for unglazed porcelain bodies it was improved around 7%, while in glazed porcelain bodies it was improved around 15% with the addition of chamotte in a traditional porcelain composition. These new porcelain compositions can be used to produce noble porcelain insulators as a more sustainable, affordable, and environmentally-friendly alternative.

Development of temmoku glazes and their applications onto different tiles under industrial fast firing conditions at 1180 °C

Temmoku glazes are special and artistic glazes that are used in certain applications. Temmokus are either slip glazes made from ferruginous clay or feldspathic type glazes containing iron oxide. Glaze composition, clay body, application method, and firing regime are the most important factors for achieving these kinds of glazes. In this study, a new temmoku glaze composition was developed and applied on floor and porcelain tile bodies, respectively. Industrial fast firing processes were conducted at Altin Seramik Factory at 1185 °C. All of the glaze surfaces were smooth and glossy after industrial fast firing. Color of the glazes was black metallic with an oil spot effect. L*a*b* values were measured by a spectrophotometer. Final surfaces of the temmoku glazes were visualized by polarized optical microscope and characterized by an X-ray diffractometer (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray (EDX). Generally, temmoku glazes displayed lower L* values on both floor tile and porcelain bodies. According to the compositional modifications, adjusting the SiO2/Al2O3 ratio was critical and the maximum Fe2O3 content should not exceed 5%. This study showed that various visual effects are related with different crystal morphology of quartz, magnetite, maghemite, and hematite and that the microstructure has an important effect on color and appearance of temmoku glazes.

Microwave sintering and fusion of low-fusing titanium body porcelain derived from sol–gel synthesis

ABSTRACTThe titanium body porcelain was synthesised through sol–gel using borate–silicate system. The porcelain was characterised by X-ray diffraction (XRD), scanning electron microscope and three-point flexure tests. The XRD and selected area electron diffraction (SAED) results showed that the porcelain was mainly amorphous. The SEM and TEM microphotographs showed that the shape of the porcelain particles was irregular and their sizes range from 5 to 25 μm, while there were no obvious pores on the porcelain surface. The flexure strength significantly increased from 18.9 to 70.6 MPa when the sintering temperature of the porcelain increased from 600 to 675°C and then slowly decreased to 49.1 MPa when the sintering temperature elevated to 700°C. The improvement of the strength was mainly due to the decrease of pores and increase of density. A closely bonded dense coating was fused on the Ti surface by microwave.

Predicting Viscosity and Surface Tension at High Temperature of Porcelain Stoneware Bodies: A Methodological Approach.

The shear viscosity and the glass-vapor surface tension at high temperature are crucial to understand the viscous flow sintering kinetics of porcelain stoneware. Moreover, the pyroplastic deformation depends on the viscosity of the whole body, which is made up of a suspension of crystals dispersed in the melt. The existing fundamental theoretical background, along with semi-empirical constitutive laws for viscous flow sintering and glass densification, can be exploited through different approaches to estimate the physical properties at high temperatures starting from amount and chemical composition of the melt. In this work, a comprehensive attempt to predict the properties of the liquid phase is proposed by means of a detailed overview of existing models for viscosity and surface tension of glasses and melts at high temperature. The chemical composition of the vitreous phase and its physical properties at high temperature are estimated through an experimental approach based on the qualitative and quantitative chemical and phase analyses (by Rietveld refinement of X-ray powder diffraction patterns) of different porcelain-like materials. Repercussions on the firing behavior of ceramic bodies, are discussed. Comparative examples are provided for porcelain stoneware tiles, vitreous china and porcelain bodies, disclosing differences in composition and properties but a common sintering mechanism.

Evaluation of Tanzania local ceramic raw materials for high voltage porcelain insulators production

Abstract This study evaluated the potential of locally sourced-ceramic raw materials in Tanzania, Pugu kaolin, Same clay, vermiculite and feldspar, for production of high voltage porcelain insulators. The chemical, mineral phases and microstructural characterization of raw materials and porcelain samples were carried out using the X-ray fluorescence, X-ray diffraction, and scanning electron microscopy techniques, respectively. The mineral phases of the fired porcelain sample identified were mullite and quartz. The porcelain bodies were fabricated using the dry pressing method by varying the composition of the selected ceramic raw materials. The physical-mechanical properties and dielectric strength were measured for each porcelain sample. The sample with the composition of 20% Pugu kaolin, 20% Same clay, 20% vermiculite and 40% feldspar was found to have the dielectric strength of 50.8 kV.mm-1, bending strength of 20 MPa and water absorption of 0.46%, which satisfies the main requisite properties for high voltage porcelain insulators.