Commercial Porcelain Research Articles

Efficient Self-cleaning and antibacterial ceramics with active sites fully exposed obtained from rare earth waste

The utilization of rare earth polishing powder waste (RPW) to prepare antibacterial ceramics can effectively avoid problems of pollution in the recycling process and waste of rare earth resources. Herein, a novel RPW-based antibacterial ceramics was developed, which possesses the core-shell structure with ceramics as the cores and the CeO2/BiOCl as the superficial coating. The antibacterial ceramics display notable antibacterial activity, and the inactivation rates of 3.3 log under visible light irradiation in 30 min and 2.4 log under darkness in 1 h were achieved, and the zone of inhibition values was found to be 16.6 mm for E.coil. The hardness of antibacterial ceramics was measured to be 897 (±38) HV, higher than commercial porcelain's hardness (600 HV). The antibacterial mechanism was verified by the Ce ion release, reactive species, and fluorescence-based live/dead cells. This study presents a novel antibacterial ceramic structure and green economic reuse method of rare earth waste.

Comparative life cycle analysis between commercial porcelain stoneware and new ones designed by using volcanic scraps

To achieve carbon neutrality by 2050, many companies have started implementing sustainability policies. The aim of this work, as result of collaboration between Universities and companies, is to assess the environmental impacts associated with the production of alternative formulations of porcelain stoneware. The proposed formulations contain extraction scraps and chamotte and have promising technological properties. A comparative analysis of the life cycle in three different scenarios was carried out to assess the environmental footprint of the final products. The analyzed scenarios were a glazed porcelain stoneware (which was taken as a reference and is commercially available), a porcelain stoneware containing pumice scraps, and one containing volcanic lapillus scraps. It was observed that the transportation of raw materials has the largest environmental impact, followed by the production and extraction of the raw materials themselves. From the performed analysis, it was possible to observe that by replacing the currently used materials by the ones hereby studied, environmental benefits can be obtained. In particular, depending on the considered pollutant, the environmental impact can be reduced between a minimum of about 8 % (Freshwater Aquatic Ecotoxicity category) to a maximum of 48 % (Acidification category). In a time when raw materials supply is difficult, the use of scraps, which would otherwise be disposed of, is particularly interesting and can lead to the production of an environmentally friendly product.

Improving plasticity of kaolins by high-energy milling for use in porcelain tile compositions

The production of porcelain tiles is increasing in Brazil besides the production of grés tiles and monoporosa is decreasing since COVID 19. Plastic clays are used in the composition of porcelain tiles to give plasticity to the pastes in the forming step. However, there is a shortage of plastic clays in south Brazil, the largest producer of porcelain tiles. Therefore, the aim of this work was to improve the plasticity of two commercially available kaolins by high-energy milling (HEM). Both kaolins were characterized before and after milling by X-ray diffraction, particle size, plasticity, and cation exchange capacity techniques. After high-energy milling, the processed kaolins were used in the composition of a commercial porcelain tile paste. The performance of the paste before and after use of the processed kaolins was determined regarding its firing shrinkage and sintering temperature. The porcelain tile compositions with the high-energy milled kaolins showed less densification during pressing and greater shrinkage after firing, but the tiles presented dimendional stability, improving the quality of the tiles.

Thermal evaluation of the use of porous ceramic plates on ventilated façades – Part I: Effect of composition and firing temperature on porosity and bending strength

AbstractThe effect of composition and firing temperature on porosity and bending strength of porous ceramic plates for using in ventilated façades were investigated. Two byproducts, basalt and lime mud, were used to obtain porous ceramic plates in accordance with the circular economy concept. Basalt, which is a fine powder‐based byproduct generated from the processing of basaltic rock, was used to replace feldspar as the flux mineral in a ceramic composition. Lime mud, a byproduct of the pulp and paper mill process and containing a high content of calcium carbonate (CaCO3), was incorporated in the ceramic composition to generate pores. The specimens were prepared using three different amounts of lime mud (20, 30, and 40 wt%) and three firing temperatures (900°C, 1000°C, and 1100°C), and their porosity and bending strength were determined. The highest performing specimen (5.1 ± 1.3 MPa bending strength and 42.6 ± 0.5% porosity) was obtained by using 40 wt% of lime mud and a firing temperature of 1100°C with potential for further thermal tests in a ventilated façade in comparison with a commercial porcelain ceramic tile as reference material.

Thermal evaluation of the use of porous ceramic plates on ventilated façades—part II: Thermal behavior

AbstractThe effects of porous ceramic plates on the thermal behavior of ventilated façades were evaluated, and the results are presented herein. Thermal behavior in a ventilated façade of specimens containing 40 wt% of lime mud and a firing temperature of 1100°C was evaluated and compared with a commercial porcelain ceramic tile, which was the reference material. An experimental apparatus was designed to evaluate the thermal performance of the studied ventilated façades. The results revealed that the ventilated façade composed of the studied porous ceramic tiles produced a greater reduction in temperature between the external environmental and the interior of a box representing a building (ΔT5) of 65.7°C, compared with the façade composed of the commercial porcelain ceramic tiles (ΔT5 = 56.0°C) and even the traditional façade (ΔT5 = 49.1°C). Thus, porous ceramic tiles based on byproducts are promising candidates for ventilated façade systems.

Measurement of Radioactivity in Some Commercial Porcelain Samples by Using HPGe Detector

Estimations of specific activity concentrations in eight commercial porcelain tiles made in different countries were performed by the use of HPGe detector. We have found that the highest specific activity concentrations for 238U, 40K were equal to (21.120 Bq/kg) and (283.862 Bq/kg) respectively, Iranian origin, while the highest specific activity concentration for 232Th was found to be equal to (29.292 Bq/kg), Iraqi origin; all of which were less than their corresponding recommended values given by (UNSCEAR, 2000). The radiation hazard indices [Iɣ , Hin ,Hex , Raeq ,DƔ , (AEDE) in and (AEDE) out] were also studied and their values were less than the allowed values determined by (UNSCEAR, 2000). Therefore, all the studied tiles of commercial porcelain are safe when used, for example, in floor constructions.

Boron mining and enrichment waste: A promising raw material for porcelain tile production

AbstractBoron mining and enrichment waste (BW) from boric acid (H3BO3) production is a by‐product of the boron industry. BW exhibits B2O3 contents of 16‐31 wt%, and therefore, could be used to effectively lower the sintering temperature of ceramics without increasing their thermal expansion coefficient. Herein, we introduced 3‐10 wt% of BW to a formulation used for commercial porcelain tile production, and achieved a sintering temperature decrease of 38°C (to 1195°C). The resulting porcelain tiles exhibited a strength of 44.80 MPa and water absorption percentage of 0.01%, and therefore, met TS ISO EN 10545 requirements. Thus, this study paves the way for the use and valorization of BW in the production of porcelain tiles and could inspire the search for other opportunities to utilize BW in ceramic production.

Towards the colonization of Mars by in-situ resource utilization: Slip cast ceramics from Martian soil simulant.

Here we demonstrate that by applying exclusively Martian resources a processing route involving suspensions of mineral particles called slurries or slips can be established for manufacturing ceramics on Mars. We developed water-based slurries without the use of additives that had a 51 wt. % solid load resembling commercial porcelain slurries in respect to the particle size distribution and rheological properties. These slurries were used to slip cast discs, rings and vases that were sintered at temperatures between 1000 and 1130 °C using different sintering schedules, the latter were set-up according the results of hot-stage microscopic characterization. The microstructure, porosity and the mechanical properties were characterized by SEM, X-ray computer tomography and Weibull analysis. Our wet processing of minerals yields ceramics with complex shapes that show similar mechanical properties to porcelain and could serve as a technology for future Mars colonization. The best quality parts with completely vitrificated matrix supporting a few idiomorphic crystals are obtained at 1130 °C with 10 h dwell time with volume and linear shrinkage as much as ~62% and ~17% and a characteristic compressive strength of 51 MPa.

Biaxial flexural strength of the bilayered disk composed of ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) and veneering porcelain

ObjectiveHerein we investigated the flexural strengths of bilayered ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) disks using different veneering porcelains. MethodsCommercial (VITA VM9, Cercon Ceram Kiss, and IPS e.max Ceram) and experimental porcelains (Vintage ZR with coefficient of thermal expansions: CTEs of 8.45, 9.04, and 9.61ppm/°C) with various layer thicknesses (1.0, 1.5, and 2.0mm) were applied to Ce-TZP/A disks (0.8mm thickness, n=180). Biaxial flexural tests of the specimens with the porcelain layer in tension were evaluated based on the piston-on-three-ball method (ISO 6872: 2008). The calculated strengths were statistically analyzed using the two-parameter Weibull distribution with the maximum likelihood estimation. ResultsAlthough no significant differences were observed among the experimental porcelains, most specimens with the thinner layer of commercial porcelain showed higher Weibull characteristic strengths at the external surfaces than those with the thicker layer. Irrespective of the porcelain material, the thinner porcelain layer showed significantly higher strengths at the interface between the layers. Fracture origins were always observed at the bottom surface and continuously propagated into Ce-TZP/A substrates. The maximum tensile stress was located at the interface in specimens with the 1.0mm porcelain layer, except for IPS e.max Ceram. Porcelain delamination was dominant in the case of the higher CTE value and thicker layer thickness of the porcelain. SignificanceThe calculated biaxial flexural strengths and the stress distributions for bilayered Ce-TZP/A disks were dependent on the porcelain materials. Optimum behavior was observed for a combination of a small CTE mismatch between the materials and a low core-to-porcelain thickness ratio.

Microstructural characterization and tribological behavior of Laser Furnace processed ceramic tiles

This paper presents, for the first time, the processing of commercial ceramic tiles by means of Laser Furnace (LF) technology and its influence on their microstructure and tribology. Commercial porcelain and white clay, partially fired ceramic tiles, were processed by this method in order to study the effect of the laser treatment and its potential to produce ceramic items on a large scale, under extreme surface temperature conditions. The microstructure and depth of the laser irradiated ceramic samples were studied by FESEM. EDX analyses were employed to study composition before and after the laser treatment. Surface roughness was determined using Confocal Microscopy, while hardness and tribological behavior were studied using Vickers indentations and a ball-on-flat apparatus, respectively.

Energy saving in sintering of porcelain stoneware tile manufacturing by using recycled glass and pottery stone as substitute materials

Commercial porcelain stoneware tiles are vitrified tiles (noted as C) that are composed of clay, feldspar, and quartz. They require high temperature sintering at 1230°C that result in high energy costs. This study aimed to compare the energy consumption during sintering process of the porcelain stoneware tiles, which recycled glass and pottery stone were used in substitution of clay, feldspar, and quartz (noted as N). The sintering temperatures of the commercial (C) and the substituted (N) tiles were, respectively, at 1230°C and 1050°C. The physical, mechanical, and chemical properties of the N tiles were compared with those of the C tiles. As a result, the N tiles showed good properties according to several standards, such as water absorption of less than 0.1% (ISO 10545-3), linear shrinkage of less than 10% (ASTM C326), modulus of rupture of more than 40N/mm2 (ISO 10545-4), and good resistance of chemicals (ISO 10545-13). The N tiles were in compliance with the ISO 13006:2012 (group BIa) Standard. In the sintering process, the energy consumption and CO2 emission of the N tiles were, respectively, 9191.24kJ/kgProduct and 0.0782kg CO2eq/kgProduct, while those of the C tiles were, respectively, 13304.84kJ/kgProduct and 0.1132kg CO2eq/kgProduct.

An estimate of quartz content and particle size in porcelain tiles from young's modulus measurements

The influence of quartz particle size, weight content and firing temperature on the Young's modulus of porcelain tiles was studied. To simulate a porcelain tile microstructure, an albite glass matrix with added crystalline quartz particles was developed. Average particle size of quartz (3.4 and 31µm) and volume content (18.5 and 37.6vol%) were varied. An acoustic impulse excitation technique was used to measure the elastic modulus from room temperature up to 700°C. Results showed that quartz has a major influence on the elastic modulus of porcelain tiles. At temperatures below 573°C, a hysteresis area between the Young's modulus curves during heating and cooling was closely related to quartz particle size. Between 573 and 700°C, the variation of the Young's modulus was related to the quartz volume fraction. By using those correlations, a prediction of quartz content and quartz particle size in commercial porcelain materials can be carried out from Young´s modulus data.

Deposition and characterization of AlN thin films on ceramic electric insulators using pulsed DC magnetron sputtering

Abstract Porcelain electric insulators are fundamental support devices to act as holders for transmission lines. The exposition to pollutants environments such as industrial areas, deserts and sea air, containing carbon, sand and salt are examples that can reduce the devices dielectric property. The present investigation aims to develop and characterize hydrophobic aluminum nitride thin films, deposited on porcelain insulators surfaces, using a pulsed direct current magnetron sputtering (PDMS). An aluminum target with 99.999% purity was used as precursor and nitrogen 99.999% purity was employed. The film characterization was performed using AFM, FEG and FTIR. The surface resistivity was evaluated by four-point probe method. Different deposition times lead to different wettability characteristics, verified by the sessile drop method using a goniometer. The experimental results show the formation of a low roughness aluminum nitride film with hydrophobic properties over the glazed surface of a commercial porcelain electrical insulator.

Increasing Bending Strength of Porcelain Stoneware via Pseudoboehmite Additions

Pseudoboehmite nanoparticles synthesized through the desulfation of Al2(SO4)3were used to investigate the reinforcement of commercial porcelain stoneware. Fractured specimens investigated by SEM suggest that the added pseudoboehmite precursor generated a nanometric primary mullite phase dispersed in the porcelain glassy phase that limited and stopped the intergranular crack propagation. The porcelain modulus of rupture increased twice the value of the modulus of rupture (108 MPa) as compared with that samples without pseudoboehmite additions. Pseudoboehmite also led to increased densification of porcelain stoneware bodies up to 1250°C as shown by thermodilatometry data.

Microhardness and Biocompatibility of Silicon Nitride Ceramic Developed for Dental Applications

Silicon nitride (Si3N4) ceramic is an attractive material for dental applications, especially used as a dental core material, due to its unique properties including high fracture toughness, high strength, high wear resistance and non-cytotoxicity. In this study, the Si3N4 ceramic was fabricated by a non-pressure sintering technique at a relatively low sintering temperature of 1650℃ in nitrogen atmosphere. Borosilicate glass and 5 wt% ZrO2-added borosilicate glass were used for coating on the Si3N4 core surface because of their compatibility in thermal expansion, high chemical resistance and bio-inert. The specimens were then fired in electric tube furnace at 1100℃. The Vickers microhardness of borosilicate glass and 5 wt% ZrO2-added borosilicate glass veneering materials were measured and compared with the commercial dental veneer porcelain as a control (VITA VMK 95). The cytotoxicity of the Si3N4 ceramic and the veneering materials were tested by MTT assay, using human gingival fibroblasts (HGF) and periodontal ligament fibroblasts (HPDLF). The results indicate that the Si3N4 ceramic and Si3N4 ceramic veneered with borosilicate glass or 5 wt% ZrO2-added borosilicate glass veneering materials tested in this study are not toxic to oral tissue and can be used to produce dental prostheses.

Shrinkage prediction during non-isothermal sintering in the presence liquid phase: New kinetic model, Part I

The thermal behavior of porcelain stoneware compositions during the sintering was investigated by hot stage microscopy, HSM, and dilatometric tests. The experiments were carried out with a commercial porcelain stoneware composition as a reference, STD, and a modified composition in which 10.0wt.% of potassium-feldspar in STD mix was replaced with the same content of nepheline syenite. In order to evaluate the effect of technical factors on shrinkage, the specimens were prepared at different milling time and forming pressures. According to HSM results, the increment in milling time of modified composition causes the improvement in dimensional stability. Also, the non-isothermal variation in shrinkage is accurately described by a new semi-theoretical model. The value of dimensionless factor, m, shows that the diffusion mechanism is a function of milling time and the forming pressure cannot change dimensionless factor. The model successfully predicted the shrinkage of bodies sintered in presence liquid phase.

Effect of microstructure on cutting processability of porcelain tile subjected to different firing cycles

Abstract The fast firing technique is one of the most important ways to save energy consumption and improve production efficiency in the porcelain tile industry. In the actual production, excessively short firing cycle time easily causes the cutting edge defects. This work examines the effect of microstructure on cutting processability of a representative composition of a commercial porcelain tile fired at 1200 °C with two different firing cycles as follows: 40 min and 60 min. The phase composition and microstructure were investigated by using a combination of techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). The result indicated that it was beneficial to extend firing cycle (from 40 min to 60 min) for the cutting processability of porcelain tiles, which was due to the formation of positive microstructures such as secondary mullite needles and small-volume residual quartz.

Comparative Study of the Thermal Shock Resistance of an Industrial Tableware Porcelain

The effect of the glazed layer and firing conditions (temperature and duration) on the thermal shocks behavior of tableware porcelains has been studied. Two types of glazed layers and three firing conditions, used industrially in the commercial porcelains manufacture, are used in this investigation. Repeated thermal shock tests showed that the glazed layer with higher alumina/silica ratio is more resistant to thermal shocks and that the slow firing cycle, even at a relatively low temperature, is very beneficial for the thermal shock resistance of the porcelain matrix. Three-point bending tests showed that the crazing phenomenon, which affects the glazed layers as well as the porcelain matrix, does not affect significantly the mechanical resistance of these materials.

Wollastonite as a Flux for Ceramics Bodies

Wollastonite is a calcium silicate mineral natural or synthetic. Commercial wollastonite starts to melt at about 1450°C and can not be considered a "flux" as alkali feldspar. For this function, it depends on the reaction with other raw materials. Faced with this, came the goal of this work which was to investigate the mechanism of action of wollastonite as a ceramic flux. The use of wollastonite in ceramic bodies was investigated by analysis of its reactivity with other materials such as quartz, kaolin, talc and feldspar. It was analyzed the technological properties of the final parts, especially in relation to the firing temperature, phase formation and technological properties (mechanical strength, porosity, etc.). The results of this characterization showed that the technical properties of the parts are developed according to commercial porcelain products.

Shade variance in ceramic restoration and shade tab: An in vitro study

Background:In clinical practice aesthetics for any restoration needs to consider the parameters of surface form, translucency and colour. To achieve ideal aesthetics the colour replication process for dental porcelain is the most important step which comprises of a shade selection phase followed by shade duplication.Materials and Methods:The ceramic brands Vita VMK95 (classic) and Ivoclar classic V were used for comparison with Vita classic shade tab guide shades A2 and B2. The samples were made of specific shape, size, and were of the recommended dimensions from investing self-cure acrylic strips to casted NiCr specimens Objective. The objective of this study was to quantify the results in CIE AE units system for the colour differences between the Vita shade guide colours and two commercial porcelains for metal ceramic crowns.Results:The results indicated that the porcelains do not match the shade guides to which they are compared and shade variations exist between different lots of porcelain from the same and different manufacturer.Conclusion:Problems identified that porcelains do not match the shade guides to which they are compared and shade variations exist between different lots of porcelain from the same and different manufacturer