Porcelain Bodies Research Articles

The sintering kinetics of shellfish porcelain reinforced by sepiolite nanofibres.

The work investigated the effect of sepiolite nanofibres on mechanical properties and sintering behaviour of shellfish porcelain. Samples of shellfish porcelain reinforced by sepiolite nanofibres were fired in an electric furnace at 1150, 1200 and 1250°C for a period of 80, 100, 120 and 140 min. Sintered samples were characterized by flexural strength, fracture toughness, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results showed that 2 wt% sepiolite nanofibres could increase the flexural strength and fracture toughness of the porcelain bodies through the fibre pullout and the weak interface mechanisms. Sintering activation energies were determined according to the linear shrinkage results. It is found that the liquid-phase sintering mechanism of shellfish porcelain with sepiolite nanofibres is a diffusion mechanism. Porcelain without sepiolite is controlled by volume diffusion, and eventually, the grain boundary diffusion began to appear with the increase of sepiolite addition.

Influence of waste glasses on the physico-mechanical behavior of porcelain ceramics

The use of wastes as substitute to traditional materials from non-renewable sources has recently increased as a result of growing interest in environmental preservation and solid wastes management. In this work, the effect of waste glasses on the physico-mechanical properties of soft porcelain is investigated. Soft porcelain bodies containing milled waste soda-lime and borosilicate glasses at varied percentage were composed and were uniaxially dry pressed under 40kN load using hydraulic pressing machine. The pressed bodies were oven dried at 110°C and were later subjected to firing at temperatures of 1000°C and 1200°C respectively. Tests such as water absorption, porosity, bulk density and firing shrinkage were used for physical characterization while flexural strength and wear loss was used for mechanical characterization under standard approach to investigate the behavior of the developed soft porcelain bodies at temperatures of 1000°C and 1200°C respectively. The results showed that higher densification was observed at 1200°C while water absorption drastically reduced below the required maximum 1% and porosity fall below 4% for both samples containing waste soda-lime and borosilicate glasses respectively. Improvements in terms of wear loss and strength properties were also observed for samples containing waste soda-lime and borosilicate glasses respectively subjected to temperature of 1200°C. This better behavior observed at temperature of 1200°C can be attributed to better glassy phase formation and mullite growth at that temperature.

PHYSICAL AND CHEMICAL CHARACTERIZATION OF WASTED TILES AS COATING MATERIALS FOR PAVEMENT SURFACE TEMPERATURE REDUCTION

Urban heat island (UHI) is the phenomenon that temperatures in urban area reach a relatively higher value than its surroundings areas due to urbanisation. Pavement is one of the urban fabrics that contribute to UHI, due to its ability to absorb high amount of heat from solar radiation. In the tile production process, cracked or broken tile bodies are not accepted as commercial products and they are too impure to be reused and is usually discarded as unsold waste. This scenario could possibly lead to environmental problems. This study focuses on three types of wasted tiles (Full Body Porcelain, Monoporosa, Glazed Porcelain) from a chosen tile industrial factory, as coating materials for pavement surface. The main purpose of this study is to obtain specific information regarding the significance characterization of three types of wasted tiles as coating materials on pavement surface. The title characterization showed that Full Body Porcelain contains the highest bulk density value of 1366.699 kg/m3 and highest particle density of 2580 kg/m3 , whereas Monoporosa has the highest porosity value of (56.8%) and Monoporosa posses the highest amount of void content (56.85%) between the aggregate particles. The X-Ray Fluorescence study shows that Full Body Porcelain contains the highest amount of SiOâ‚‚ (66.50 wt%), when compared to other two wasted tiles used during this study. As a conclusion these three types of wasted tiles have the potential and promising UHI mitigation benefits to be considered as coating materials for the pavement surface.

EFFECT OF DIFFERENT METAL OXIDES ON VICKERS HARDNESS OF THE FRIT BASED CRYSTALLINE GLAZES

Frit based glaze is a thin glassy surface coating which gives technical and aesthetic value to the ceramic product after firing. Crystalline glazes are one of the most important type of artistic glazes formed through a controlled crystallization of glass during a special heat treatment. Crystals are visible to the naked eye and the product can have only a few single crystals on the surface or the entire surface can be coated with crystals. The preferred clay substrate for crystalline glazes is porcelain and in some cases may be used for the macrocrystallines. Usage of these types of glazes as porcelain tile coatings is an alternative choice for relevant ceramic industry and these glazes strongly enhance the visual quality of the final products. When designing crystalline glazes for porcelain tiles; besides the chemical composition, mechanical properties such as hardness is also an important factor. Within the scope of experimental studies, frit based crystalline glazes which consist of different nucleating agents such as MnO, Fe 2 O 3 , NiO, CoO, CuO and Cr 2 O 3 were applied on the raw porcelain bodies and then subjected to a special heat treatment cycle. The aim of this study was to investigate the effect of different metal oxides on crystallization capacity of newly developed fritted glaze compositions and Vickers hardness of the final products. Micro hardness of the glazes was measured with Vickers hardness test method. Characterization of crystalline glazes was done by x-ray diffraction (XRD) technique.

Using white cement as a source of calcium oxide in Anorthite body

Anorthite is a rare compositional variety of plagioclase. This mineral is a type of calcium-rich plagioclase feldspar which has great properties such as low thermal expansion coefficient and high modulus of rupture. Therefore, physical properties of hard porcelain bodies will be improved by creating anorthite phase. According to limitation of anorthite natural sources, various sources were used to synthesis of anorthite. In this paper, white cement was introduced as a new calcium oxide source to reach anorthite phase. For this purpose, a standard composition for hard porcelain was prepared by addition of 50 wt% kaolin, 25 wt% potassium feldspar and 25 wt% quartz. Six additional body mixtures were formulated partially by replacing 0, 3, 4.5, 6, 7.5 and 9 wt% of potassium feldspar by white cement. The linear shrinkage, water adsorption, modulus of rapture (M.O.R), and bulk density of fired body were calculated. Phase characterization was accomplished by X-ray diffractometer (XRD) and scanning electron microscopes. By replacing potassium feldspar with white cement, anorthite was appearance in fired body at 1250 °C. This replacing decreases bulk density, linear shrinkage and modulus of rapture. Although, water adsorption and consequently firing temperature increase by replacing white cement but 1250 °C was a good temperature for firing replaced bodies.

Synthesis and Characterization of Porcelain Body Developed from Rice Husk Ash

Synthesis and Characterization of Porcelain Body Developed from Rice Husk Ash

Influence of alumina and silica addition on the physico-mechanical and dielectric behavior of ceramic porcelain insulator at high sintering temperature

The high-strength electrical porcelain insulator plays a vital role in the power industry. The present study investigates the effect of alumina and silica addition on the physico-mechanical and electrical properties of porcelain bodies over high sintering temperatures. The pallets were prepared in different shapes and dimensions with the help of hydraulic press machine by pressing at 160MPa for a period of 10-min. Different characterizations techniques such as; dilatometer, X-ray diffraction (XRD), and scanning electron microscopy (SEM) used to evaluate the thermal, structural, and microstructural changes, respectively by increasing the concentration of silica (0–20wt.%) and decreasing alumina (45–25wt.%) concentration for the base composition of porcelain insulator. The measurement of mechanical strength and physical behavior were analyzed for all the samples prepared with different compositions of alumina and silica with varying sintering temperature (1250 and 1350°C). The sample with a composition having silica 10wt.% of alumina 35wt.% and sintered at 1350°C, shows the maximum density of 2.55g/cc with water absorption of 0.94%. This sample also shows the highest value of bending and compressive strength of 129±5 and 202±5MPa respectively. The highest dielectric value of 5.75 and minimum dielectric loss of 0.05 at a frequency (2–20GHz) is achieved for the same composition with silica 10wt.% of alumina 35wt.% sintered at 1350°C. The composition having silica 10wt.% with alumina 35wt.% sintered at 1350°C, has enormous potential to serve as a high strength refractory and a dielectric ceramic material for microwave applications.

Influence of Spodumene Added as a Fluxing Agent on the Properties of Alumina Porcelain Insulator

Alumina porcelain electrical insulators were prepared using Li2O-bearing spodumene flux as a partial substitute for feldspar. The effects of spodumene on microstructure, crystalline phases, physical properties, modulus of rupture, dielectric breakdown strength and volume resistivity were investigated. The samples with spodumene content >5 mass-% sintered at 1350°C showed both zero percent water absorption (WA) and apparent porosity (AP). Density was found to decrease with increasing spodumene content from 2.39 g/cm3 (at 5 mass-% spodumene) to 2.37 g/cm3 (10 mass-%) to 2.33 g/cm3 (15 mass-%). This may be due to the irreversible phase transformation of α-spodumene to β-spodumene, which accompanies a change in density of spodumene from α-phase (3.20 g/cm3) to β-phase (2.35 g/cm3). The crystalline phases were characterised by X-ray diffraction and scanning electron microscope. They showed that spodumene favours crystallisation of elongated needle-like mullite and spodumene solid solution that coexist with alumina particles embedded in the glassy matrix of bodies sintered at 1350°C. This resulted in an increase in modulus of rupture and enhanced the electrical properties of the porcelain bodies. The maximum 71 N/mm2 modulus of rupture (MOR), dielectric strength of 21 KV/mm and electrical resistivity equal to 10×1012 Ω·cm were recorded with 10 mass-% spodumene.

Optimizing of near infrared region reflectance of mix-waste tile aggregate as coating material for cool pavement with surface temperature measurement

The heat generated from dark color asphalt, which is low in surface reflectance mainly contributes to the environmental problem called as urban heat island. Low reflectance at high energy wavelength of sunlight, such as visible light and infrared region will cause the pavement to have high surface temperature, due to high energy absorption from solar radiation. This paper presents the optimization result of cool pavement coating material based on selected tiles aggregate to achieve high near infrared region (NIR) reflectance. Three types of waste tiles were used in this study which are Full Body Porcelain (FBP), Monoporosa (MP) and Porcelain Glaze (PG). All the tiles were prepared in the form of aggregates. A linear model was formed as a function of mix tiles fraction and the analysis of ANOVA suggest that the linear term used for this model is significant. Diagnostics of the model was evaluated using box-cox plot, normal plot of residuals and optimized to predict the mix of the different type of tiles to produce the highest surface NIR reflectance value. The first solution suggests that 100% of MP tile can provide NIR reflectance of 0.53, whereas the second solution suggest that the combination of 50% FBP and 50% of MP tile aggregates could give NIR reflectance value of about 0.51. Experimental work on measuring surface temperature found that optimized samples, M1 and M2 with high NIR reflectance could significantly reduce surface temperature of asphalt pavement at range of 4.1°C–9.6°C. In conclusion, the results of optimization is reliable and this method able to provide significant information on optimizing mix of tiles material as to achieve high NIR reflectance value for coating materials of cool-pavement.

Phase and microstructural evolution in quartz-free porcelain tile compositions

In the present investigation, three quartz-free porcelain compositions were prepared where quartz was fully substituted by fly ash (VPF 1) and feldspar was partly substituted by blast furnace slag (VPF 2) and basic oxygen furnace slag (VPF 3). A quartz-containing porcelain (VPQ) was also considered to compare the results with quartz-free porcelain bodies. Phase transformation and mass loss of the prepared batches were measured up to 1150 °C by simultaneous thermogravimetric and differential thermal analysis (TG-DTA). Endothermic peaks in the range of 519.27–539.01 °C were mainly due to dehydroxylation of kaolin. Exothermic peaks in the range of 814.01–1060.55 °C were attributed to mullite crystallization. No major difference was found in TG-DTA data of quartz-containing sample. Fabricated green samples were heated in the temperature range of 1100–1280 °C based on the softening point (PCE values) of the experimental bodies. Physico-mechanical properties, phase, and microstructure of the heated samples were evaluated by standard techniques. Early vitrification was observed in the case of VPF 1 and VPF 3. Quartz-containing body (VPQ) was vitrified at 1280 °C. X-ray diffraction (XRD), field emission scanning electron microscopic (FESEM), and energy dispersive X-ray analysis (EDAX) studies confirmed the presence of quartz (SiO2) and mullite (3Al2O3·2SiO2) in VPF 1 while quartz, mullite, and anorthite (CaO·Al2O3·2SiO2) were observed in VPF 2 and VPF 3. Alumina-enriched slag used in this study was contributed towards anorthite crystal formation. In quartz-containing body, major phases were found to be quartz and mullite.

The effect of different fluxing agents on the sintering of dry pressed porcelain bodies

The aim of the article is to find the optimal fluxing agent for porcelain body regarding to the possibility of the lowest firing temperature. Sintering behaviour of dry pressed test samples made from the mixture of kaolin and three different types of industrially milled feldspar rocks, bone ash and quartz sand with similar granulometry as dependence of water absorption on the firing temperature was investigated. The most intensive fluxing agent for the sintering is bone ash—the mixture containing bone ash (20wt.%) showed sintering temperature 1200 °C. That is about 50 °C lower compared with the most intensive feldspar based fluxing agent—potassium feldspar rock containing 75% of pure microcline.

Study on Phase and Microstructure of the White Porcelain from Huangye Kiln

The white porcelain samples of the four periods of Huangye kiln were studied in this paper, and the samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the material phase is basically the same of the white porcelain bodies from Huangye kiln, and mainly mullite, alpha quartz and cristobalite, unmelted quartz and a small amount of clay phase; There are some round bubbles in HuangYe kiln white porcelain, glazes, so are some feldspathic crystals with micro-level needles or columnar. It is evident to observe phase separation structure, which is accompanied by the birth. Apart from some pores, unfused quartz particles, larger Ti particles, mullite crystals and quartz crystals can also be found in the embryo of Huangye kiln white porcelain.

Pyroplastic deformation behavior of vitreous porcelain bodies in presence of spodumene

Pyroplastic deformation tendency of vitreous body compositions is a major production problem. In this work, a vitreous sanitaryware body composition (ST) which was developed in a previous work was taken as standard, and the sodium feldspar content of this recipe was changed with spodumene as a source of Li2O. Six different compositions were formulated by applying two different approaches: weight percent formulation and Seger formulation. Bodies were fired at 1250 °C and after firing deformation, firing shrinkage, and water absorption values were measured. Pyroplastic deformation behavior of bodies was determined by using fleximeter with a peak temperature of 1250 °C. According to the results, it was observed that spodumene addition with Seger formulation gives better results than weight percent formulation. The body which contains 0.1 mol% of Li2O (L2 body) has deformation value which is 11% lower than that of standard body due to its different phase composition and microstructure than ST body.

Inorganic wastes in glaze recipes and their effects on microstructure

This work reports on recycling various amounts of inorganic wastes (scraps of glass packaging waste, key sawdust, copper slag, and pyrite ash) into artistic ceramic glazes. These waste materials were used in the range of 0.6–20% in artistic glaze compositions. Glazes were composed of a mixture of acidic (SiO2, B2O3), basic (Na2O, K2O, CaO, ZnO, PbO), and amphoteric (Al2O3, Cr2O3) oxides and formulated using the Seger method. These glaze compositions were applied over the surface of the porcelain body and fired at 1080 °C and characterized by field emission scanning electron microscope (FESEM) coupled with energy dispersive X-ray spectrometry (EDS). As a consequence, results showed that, different inorganic wastes could be used in artistic glaze compositions for the obtaining attractive colors and textures.

Foaming inhibition of SiC-containing porcelain ceramics by using Si powders during sintering

Porcelain green bodies were prepared using porcelain stoneware tile powder as the major raw material, with silicon carbide (SiC) and Si powders as additives. These were fired at 1000–1200°C. The effects of Si powder addition on the microstructure, crystalline phases, and relative density of SiC-containing porcelain bodies were systematically investigated, and the related mechanism was also discussed in detail. The results show that even with the addition of a small amount of Si powder, the foaming degree of the porcelain bodies containing SiC with particle size and content in a wide range can be effectively inhibited. In particular, this effect becomes more pronounced as the Si powder particle size is reduced. It is believed that this work will have important scientific value for the oxidation protection of SiC and the foaming inhibition during the direct recycling of large amounts of polishing porcelain tile residues in the world.

Porcelain shards from Portuguese wrecks: Raman spectroscopic analysis of marine archaeological ceramics

Raman spectroscopic analysis of shards recovered from two Portuguese shipwrecks, the Santo Espirito (1608) and the Santa Maria Madre de Deus (1643), believed to be carrying porcelains of the Ming period have revealed some interesting and novel results that inform historical ideas of porcelain production. The porcelain body of two of the four shards from the Santa Maria Madre de Deus were found to contain anatase, a low temperature polymorph of titanium dioxide, and β-wollastonite a mineral characteristic of soft-paste porcelains that are made at medium-temperature firing conditions. Previously, β-wollastonite has been found in a range of sixteenth to nineteenth century European porcelains but this is the first report of its detection in porcelain believed to be from the Ming period. These same shards exhibited unusual spectral features that were attributed to the resonance enhancement of rare earth elements that resulted from excitation using a near-infrared source.

Influence of bone porcelain scraps on the physical characteristics and phase composition of a hard porcelain body

Hard porcelain is constituted in the alkali oxides-alumina-silica ternary system, and produced by a mixture of clay-feldspar and silica. The most important properties of this porcelain are high mechanical strength, translucency and whiteness. These properties depend on quality of raw material, firing temperature and soaking time. In bone porcelain bone ash was added to body composition up to 50wt.%. Generally hard porcelain and bone porcelain scrap cannot be reused in body composition. Whereas using these scrap could help natural resources. In this research using bon porcelain scraps in hard porcelain body have been investigated. Results show, this substitution decrease firing temperature, linear expansion and increase glass, probability of deformation and total shrinkage. Using 6wt.% bone porcelain scraps to hard porcelain body composition besides improving some properties, increases 1340°C firing mechanical strength two times and helps natural resources.

Ceramic porcelain stoneware production with Spanish clays purified by means of the removal of iron compounds and organic matter using physical methods

As the production of ceramic porcelain stoneware in Spain is totally conditioned by the importation of ball clays, because of the lack of adequate Spanish ball clays, this work has focused on the formulation of ceramic porcelain body from Spanish clays purified by means of physical removal processes. This method was applied to three Spanish clays containing common clay impurities of iron (hematite and siderite) and organic matter. Iron removal was carried out using the wet sieve method, the hydrocycloning method and the electromagnetic filtering method, obtaining a reduction in iron content of up to 80wt%, while the clay containing organic matter was treated thermally at 400°C for 30min so as to leave it almost completely purified. These treated clays, after being characterized (chemical and mineralogical composition, plasticity, organic carbon, thermal behaviour and colour), were used in the porcelain stoneware body composition instead of imported clays, the result being a composition capable of substituting the standard porcelain stoneware formulation in terms of sintering, morphology, colour, flexural strength and dilatometry.

Effect of calcined colemanite additions on properties of hard porcelain body

Abstract Utilization of calcined colemanite as a sintering aid in hard porcelain body, prepared by slip casting route using aqueous suspension containing mixtures of kaolin, quartz and potassium feldspar, was investigated. After calcination, colemanite powders were added to the admixture of porcelain by partial substitution with potassium feldspars in the range of 0–5 wt% to discover its influences on the densification and technological properties of the final product. Through optimization of process parameters of ceramic suspensions by using appropriate dispersing agents and facilitating densification by calcined colemanite addition, hard porcelain possess high strength was obtained. When relationship between the additive concentration with temperature was established, it is found that porcelain formulations resulted in substantial reduction of firing temperature about 50 °C without compromising its quality by 1 wt% calcined colemanite addition.

Experimental evaluation of thermal performance of cool pavement material using waste tiles in tropical climate

Thermal performance are important parameter that represent the characteristic of cool pavement. The purpose of this paper is to present the findings on experimental result of thermal performance of the coating materials, which were developed from three types of waste tile aggregate, namely Full Body Porcelain (FBP), Monoporosa (MP) and Porcelain Glaze (PG). The samples were prepared based on the optimal design mix as proposed during optimization process based on surface temperature behavior of the samples. Experimental work was conducted in 24-h basis for continuously 14days at actual tropical weather climate. The results showed that sample M1 with 100% of FBP provided the best result in terms of thermal performance, also the material was able to obtain highest surface temperature reduction up to 6.4°C during peak period and solar reflectance of 0.49 at near infrared region. Statistical analysis shown that sample M4, 100% of PG tile aggregate, depicted a less desirable result due to its surface temperature reduction was not significant as compared with other investigated samples, which is only 4.32° during peak period. Overall result conclude that both material FBP and MP have a good potential to be used as cool pavement coating material based on its thermal and spectral performance. Thus, this study provides a useful information on the selection of tiles material that could be used as cool-pavement coatings, and contribute for a more potential measurement in mitigating urban heat island effects.