Green Ceramic Tiles Research Articles

Valorization of Al slag in the production of green ceramic tiles: Effect of experimental conditions on microstructure and crystalline phase composition

AbstractThis work reports the results of an investigation aimed at the development of sintered glass‐ceramic tiles by the sinter‐crystallization of mixtures composed of aluminum slag and reclaimed packaging glass. The thermal behaviors of mixtures incorporating 50 and 60 wt% Al slag were established by differential thermal analysis (DTA). Green compacts were sintered in a temperature range of 800°C‐1050°C and then soaked for 10‐60 minutes. The mineralogical characterizations of the sintered materials were obtained by X‐ray diffraction (XRD). The achieved results indicated that the sintering of aluminum slag and packaging glass reclaimed led to a glass‐ceramic material composed mainly of needle‐like crystals of wollastonite (CaSiO3). The bloating of samples during firing was evaluated according to a Cougny predictive diagram. After initial observations and according to bending strength characterizations, sintered tiles prepared from aluminum slag and glassy sand are appropriate for floor pavement and wall covering.

Recycling of Malaysia's EAF steel slag waste as novel fluxing agent in green ceramic tile production: Sintering mechanism and leaching assessment

Abstract Electric arc furnace (EAF) slag is one of the most common by-products in the steelmaking industry. Despite various efforts of using this waste, there is yet a clear indication of EAF slag being recycled into commercial ceramic products, and most EAF slag ended up being disposed of through landfilling. Thus, a more thorough assessment is necessary to assure and convince the public regarding the potential benefits of incorporating EAF slag into the production of commercial ceramic products. In this research work, EAF slag was used as raw materials in the production of ceramic tiles. The EAF slag was crushed and ground into micron size powder before wet-mixed and milled with ball clay according to specific body formulations. This mixture was dried, compacted and fired at 1100–1180 °C. The results showed that body formulation of 50 wt% EAF slag–50 wt% ball clay and fired at 1180 °C yield ceramic tiles with most favorable properties with lowest water absorption (0.16%), lowest apparent porosity (0.48%), highest bulk density (2.95 g/cm3), and highest modulus of rupture (92.4 MPa). A sintering mechanism analysis was conducted, and it was found that the EAF slag functions as a fluxing agent to form a glassy phase, while contributed to the formation of anorthite and wollastonite during firing. The presence of these phases enhanced the densification of ceramic tiles. A leaching assessment was conducted on the ceramic tile samples, and the researchers found that heavy metal concentrations in the leachate are within the safety limit regulated by the Department of Environment Malaysia when the tiles are fired at 1180 °C. Through benchmarking with commercially available ceramic tiles and MS ISO13006:2014 Standard, the EAF added ceramic tiles have great potential to be used as heavy-duty floor tiles.

Laser ultrasonics for bulk-density distribution measurement on green ceramic tiles.

In this paper a Laser Ultrasonics (LUT) system is developed and applied to measure bulk density distribution of green ceramic tiles, which are porous materials with low heat conductivity. Bulk density of green ceramic bodies is a fundamental parameter to be kept under control in the industrial production of ceramic tiles. The LUT system proposed is based on a Nd:YAG pulsed laser for excitation and an air-coupled electro-capacitive transducer for detection. The paper reports experimental apparent bulk-density measurements on white ceramic bodies after a calibration procedures. The performances observed are better than those previously achieved by authors using air-coupled ultrasonic probes for both emission and detection, allowing to reduce average uncertainty down to about ±6 kg/m3 (±0.3%), thanks to the increase in excitation efficiency and lateral resolution, while maintaining potential flexibility for on-line application. The laser ultrasonic procedure proposed is available for both on-line and off-line application. In this last case it is possible to obtain bulk density maps with high spatial resolution by a 2D scan without interrupting the production process.

Recycling of Malaysia’s electric arc furnace (EAF) slag waste into heavy-duty green ceramic tile

Recently, various solid wastes from industry such as glass waste, fly ash, sewage sludge and slag have been recycled into various value-added products such as ceramic tile. The conventional solutions of dumping the wastes in landfills or incineration, including in Malaysia are getting obsolete as the annual huge amount of the solid wastes would boost-up disposal cost and may cause permanent damage to the flora and fauna. This recent waste recycling approach is much better and greener as it can resolve problems associated with over-limit storage of industrial wastes and reduce exploration of natural resources for ceramic tile to continuously sustain the nature. Therefore, in this project, an attempt was made to recycle electric arc furnace (EAF) slag waste, obtained from Malaysia’s steel making industry, into ceramic tile via conventional powder compaction method. The research work was divided into two stages. The first stage was to evaluate the suitability of EAF slag in ceramic tile by varying weight percentage of EAF slag (40wt.%, 50wt.% and 60wt.%) and ball clay (40wt.%, 50wt.% and 60wt.%), with no addition of silica and potash feldspar. In the second stage, the weight percentage of EAF slag was fixed at 40wt.% and the percentage of ball clay (30wt.% and 40wt.%), feldspar (10wt.% and 20wt.%) and silica (10wt.% and 20wt.%) added was varied accordingly. Results obtained show that as weight percentage of EAF slag increased up to 60wt.%, the percentage of apparent porosity and water absorption also rose, with a reduction in tile flexural strength and increased porosity. On the other hand, limiting the weight percentage of EAF slag to 40wt.% while increasing the weight percentage of ball clay led to a higher total percentage of anorthite and wollastonite minerals, resulting in higher flexural strength. It was found that introduction of silica and feldspar further improved the flexural strength due to optimization of densification process. The highest flexural strength, lowest apparent porosity and water absorption of EAF slag based tile was attained at the composition of 40wt.% EAF slag – 30wt.% ball clay – 10wt.% feldspar – 20wt.% silica. The properties of ceramic tile made with EAF slag waste (up to 40wt.%), especially flexural strength are comparable to those of commercial ceramic tile and are, therefore, suitable as high flexural strength and heavy-duty green ceramic floor tile. Continuous development is currently underway to improve the properties of tile so that this recycling approach could be one of the potential effective, efficient and sustainable solutions in sustaining our nature.

Estimation of Ultrasound Velocity Spatial Distributions in Green Ceramic Tiles

From analysis of used and applicable quality control systems of ceramic tiles is clearly seen that the ultrasonic measurement systems have significant advantages. Each manufactured product in this case will be evaluated and the result will be obtained with a sufficient accuracy. Therefore, one of the applicable ultrasonic measurement systems for measurement of the density of ceramic tiles is analyzed in this article. In this case, ultrasound velocity measurements were performed in the sectors with a different thickness of the 0.105 m x 0.105 m size green ceramic tile using ultrasonic transducers developed in the Ultrasound Institute of Kaunas University of Technology with different acoustic contact zones. Such approach was necessary because the thickness of the tile in these zones is quite different. DOI: http://dx.doi.org/10.5755/j01.eee.18.9.2810

From the experimental simulation to integrated non-destructive analysis by means of optical and infrared techniques: results compared

In this work the possibility of modeling manufacturing ceramic products is analyzed through the application of transient thermography, holographic interferometry and digital speckle photography, in order to identify the subsurface defects characteristics. This integrated method could be used to understand the nature of heterogeneous materials (such as plastic, sponge simulating a void, wood, aluminum) potentially contained within ceramic materials, as well as to predict crack formation due to them. The paper presents the analysis of green ceramic tile containing defects of different types and sizes located at different depths. The finite element method is used for solving the problem of transient heat transfer occurring in experimental conditions. Unknown parameters of the numerical model (such as convective heat transfer coefficients and sample surface emissivity) were adjusted to obtain numerical simulation results as close as possible to those obtained experimentally. Similarities and differences between experimental and simulated data are analyzed and discussed. Possibilities for improving the results and further developments are proposed.

Application of ultrasonic measurement method for investigation of green ceramic tiles

High quality requirements are established for ceramic tiles manufacturing, because they must be weather-resistant, durable, in general, hard, wear and corrosion resistant and also can withstand high stresses at elevated temperatures. One of the possible control methods of the manufactured tiles quality is ultrasonic method based on measurement of ultrasonic wave propagation speed. However, measurements of ultrasonic wave velocity in green ceramic tiles with an uneven surface are difficult. Therefore attention must be directed to the individual measurement problems of this method, which are the following: uneven surface of the inspected tile; necessity of a dry acoustic contact, non-uniform elastic properties of the tested tile.http://dx.doi.org/10.5755/j01.u.66.4.1023

Measurement of the Apparent Density of Green Ceramic Tiles by a Non-contact Ultrasonic Method

This paper discusses the problem of the measurement of the apparent density of green ceramic tiles during production. This is a fundamental parameter for the quality of the final product. In fact, the apparent density determines the entity of the dimensional shrinkage of the ceramic body during the firing of tiles, and it is proportional to the final mechanical resistance. Currently, non-destructive systems for the on-line measurement of this parameter are not available. The work presents an innovative method for non-intrusive measurement of the apparent density of green ceramic tiles during the production stage. This method uses non-contact ultrasonic probes. The time of flight of ultrasonic waves is measured during the transmission through the tile. From the time of flight, with the distance between probes known, the propagation velocity can be achieved, which is proportional to the apparent density. The conversion factor between velocity and apparent density is determined by a calibration procedure with a reference method of known uncertainty, e.g. based on a hydrostatic weighing in a mercury bath. This experimental procedure is extensively validated in the work and supported by a theoretical model. The paper presents the theory on which this measurement method lays and the instrumental apparatus, and discusses in detail the analysis of uncertainty. In the end, the paper presents the results of an on-line application.

Aphid Attraction and Preference for Soybean and Pepper Plants Infected with Potyviridae

The progress of nonpersistently transmitted virus epidemics can be substantially altered by the degree of aphid attraction and preference for virus-infected plants. Our objective was to determine whether color or odor-mediated cues of plants infected with Potyviridae mediate aphid attraction. We found that Myzus persicae (Sulzer) and Rhopalosiphum maidis (Fitch) preferred alighting on intensely (highly saturated) yellow than on green (plant-like) or brown (soil-like) ceramic tiles, and expressed no preference for landing on leaves infected with soybean mosaic virus (SMV) or on chlorophyll-deficient soybean leaves. Furthermore, neither aphid species showed odor-mediated attraction to leaf extracts of SMV-infected leaves. Also, R. maidis remained longer on uninfected than on SMV-infected soybean plants before taking flight, although M. periscae exhibited no preference. Neither aphid species had a preference to remain on healthy or potato virus Y-infected plants. Therefore, we conclude that both aphid species when landing are equally likely to alight on healthy or SMV-infected soybean plants in the field, but R. maidis is likely to remain a shorter time on SMV-infected than on healthy plants before taking off. The fact that aphids leave the infected plant soon after probing increases the probability of finding another plant and making an infective probe before the vector loses its potential to inoculate the virus. These results could be used to increase the precision of existing simulations models, such as the one previously developed for SMV.

Non-Destructive Evaluation of Green Ceramic Body Density by Ultrasonic Technique

Laboratory measurements of spatial density distribution in green ceramic tiles were implemented using ultrasonic contact coupling measurement method. The main objective of these measurements is to measure spatial density distribution in pressed green ceramic tiles. Measurements of longitudinal ultrasonic wave propagation velocity were carried out using pulse and correlation methods and the tile density values were calculated. Evaluation of the measurement method, estimation of uncertainty of measurements and analysis of further improvements purposed to adapt it for on-line measurements in a production process were carried out. Ill. 7, bibl. 16, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.360