Clay-based Ceramics Research Articles

Analysis of the Mechanical Properties of Structural Ceramics Made from Aggregate Washing Sludge and Manganese Mining Waste.

The construction sector is presently among the most resource-intensive industries, driving a substantial body of research dedicated to the development of more sustainable materials to address these demands. A particularly promising approach within the framework of the circular economy is the repurposing of waste as a principal raw material for the creation of new construction products. Within this context, the primary aim of this study is to engineer ceramic materials for brick production using 100% waste-derived inputs, specifically aggregate washing sludge and manganese mining by-products. To evaluate the potential of these sustainable ceramic materials, an extensive investigation was conducted, encompassing both physical and mechanical testing, as well as a thorough characterisation of the waste inputs. For this purpose, a series of ceramic specimens were fabricated with varying proportions of mining residues and aggregate washing sludge, adhering to the conventional protocols employed in the manufacture of ceramic bricks. The results demonstrate that these sustainable ceramics exhibit a linear shrinkage reduction of up to 5% compared to traditional clay-based ceramics. Furthermore, they show water absorption levels-whether via capillarity, cold water, or hot water absorption-that are up to twice those observed in conventional clay ceramics, while maintaining comparable density values. This increased absorption, however, correlates with a reduction in mechanical strength at higher concentrations of manganese waste, yet the material continues to meet the minimum strength requirements as specified by industry standards for such products. In conclusion, this research introduces a novel, sustainable ceramic material that not only reduces economic and environmental costs but also adheres to the required performance criteria for construction applications.

Processing, Microstructure, and Performance of Robocast Clay-Based Ceramics Incorporating Hollow Alumina Microspheres.

The restoration of ancient ceramics has attracted widespread attention as it can reveal the overall appearance of ancient ceramics as well as the original information and artistic charm of cultural relics. However, traditional manual restoration is constrained due to its time-consuming nature and susceptibility to damaging ancient ceramics. Herein, a three-dimensional (3D) printing technique was employed to accurately restore Chinese Yuan Dynasty Longquan celadon using hollow Al2O3 microsphere-modified 3D printing paste. The results show that the hollow Al2O3 microsphere content plays a vital role in the printability, physical properties, and firing performance of the modified 3D printing paste. The printed green bodies show no noticeable spacing or voids under moderate rheological conditions. The as-prepared ceramic body modified with 6 wt.% hollow Al2O3 microspheres and fired at 1280 °C exhibits optimal bending strength of 56.66 MPa and a relatively low density of 2.16 g∙cm-3, as well as a relatively uniform longitudinal elastic modulus and hardness along the interlayer. This 3D printing technique based on hollow Al2O3 microsphere-modified paste presents a promising pathway for achieving non-contact and damage-free restoration of cultural relics.

Assessment of Applicability of Bentonite Clay-Based Ceramics for Immobilization of Radioactive Waste from Pyrochemical Processing of Spent Nuclear Fuel

Assessment of Applicability of Bentonite Clay-Based Ceramics for Immobilization of Radioactive Waste from Pyrochemical Processing of Spent Nuclear Fuel

The Apparatus for Thermomechanical Analysis of Clay-based Ceramics

Abstract A dynamic thermomechanical analysis (D-TMA) apparatus is described for measuring the resonant frequency of the flexural vibration and the internal damping of the sample using the impulse excitation technique (IET). Since the measurement is conducted at temperatures up to 1250 °C, an electromagnetic impulser is used for excitation. The free vibrations are registered by an electret microphone, stored and then converted into a frequency spectrum using the fast Fourier transform, from which the resonant frequency can be found. The furnace is built from refractory porous alumina bricks and alumina fiber pads. The heating elements are four SiC rods connected to a temperature controller. The temperature is measured with a Pt-PtRh10 thermocouple in close proximity to the sample.

Interaction between Armenian clay-based ceramics and model wine during storage

Wine made or stored in clayware ceramic pots attracts the attention of consumers, but this practice is less studied than when classic stainless steel tanks or wood barrels are used. It is known that wine can be influenced by the container in which it is aged. To analyse the influence of ceramics on the chemical composition of wine, Armenian clay-based ceramic tablets were immersed in model wine and aged from 1 hour up to 16 months at 25 °C in darkness. The concentrations of 26 elements (namely: Al, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sr, Ti, V, W and Zn) in 19 samples were determined by ICP-AES analysis. Proton time domain NMR relaxometry was used to characterise the iron redox processes that occurred in the model wine in contact with a ceramic. A fast increase in the pH of the model wine in contact with the bare ceramic tablet (from 2.35 to 5) was recorded in 4 days. The coating of the ceramic tablets with beeswax showed a significant effect on the interaction between the model wine and the ceramic.

Application of β-Wollastonite on Bulk Density and Ignition Loss of Clay-Based Ceramic Materials

This work focuses on the effect of β-wollastonite percentage with different particle sizes on the bulk density and weight loss of clay-based ceramics. The ceramic bodies were prepared by mixing clay with a synthesized β-wollastonite (5%, 15%, and 25%) using a solid slip casting method. The clay (75 µm) and β-wollastonite (63, 75, and 125 µm) were mixed and fired at 950°C, 1000°C, and 1050°C of firing temperatures. The fabricated ceramic material exhibited a maximum bulk density of 2.35 g/cm3 on 25% content of β-wollastonite, 63 µm particle size of β-wollastonite, and 1050°C of firing temperature. However, a minimum bulk density of 1.87 g/cm3 was found on 25% content of β-wollastonite, 125 µm particle size of β-wollastonite, and 950°C firing temperature. A minimum of 2.32% ignition loss was recorded on a ceramic specimen that contained 25% of β-wollastonite with a particle size of 125 µm and fired at 950°C of firing temperature. In contrast, a maximum of 4.37% ignition loss was observed at a ceramic body made up of 5% of β-wollastonite content with 63 µm particle sizes and fired at 1050°C. In general, the result shows that the firing temperature, the particle size of β–wollastonite, and the addition of β–wollastonite have a great effect on the bulk density and ignition loss of the clay ceramic materials.

Effect of boron sources in the thermal behavior of a clay-based ceramics

Boron oxide sources as fluxing agents for clay-based materials have been a problem for the high solubility of these additives, however the dry milling-mixing-granulating route for clay based ceramics has been proposed and implemented with noticeable energetic advances.In the present study, the role of different boron oxide sources in the thermal behavior and sinterability of ceramic materials based on kaolinite clay was evaluated.Four boron sources were evaluated: Boric acid, borax, colemanite and ulexite. Four binary mixtures were made in a planetary mill to obtain uniform mixtures. For systematic comparison, the boron content added in all samples was 1 wt%. The thermal behavior evaluation of the mixtures was carried out by a multi-technique approach accompanied by textural, microstructural characterization complemented by a deep crystalline and non-crystalline phase evolution.Ulexite and borax presented the highest fluxing effect and colemanite has an even more moderate effect than boric acid. The observed microstructure was similar to other clay-based ceramics, with quartz grains, cristobalite and mullite embedded in the silica-based vitreous phase.The present study provides information for the additional design of clay-based materials with boron oxides as fluxing agents. The dry route alternative for using these agents was effective.

The effect of the addition of construction & demolition waste on the properties of clay-based ceramics

Waste glass and reclaimed brick are types of construction and demolition waste (C&DW) that could potentially be used as secondary raw materials in the production of ceramics. Ceramics based on clay, waste demolished brick (5-15 wt.%) and waste glass (5-20 wt.%) were produced by pressing (P = 68 MPa) and subsequently sintered at 900, 950, 1000, and 1050 oC for one hour. The physical and mechanical properties of the ceramics obtained were evaluated. The addition of demolished brick decreased the density and mechanical properties of the clay specimens and increased the water absorption. The incorporation of waste glass improved the sintering behavior and its mechanical properties. The addition of 20 wt.% waste glass and 10 wt.% waste demolished brick into the clay matrix improved the flexural strength by up to 20.6 % and decreased the water absorption by up to 22 %. The approach presented promotes an opportunity to recycle construction and demolition waste into alternative resource materials, and represents a positive contribution to the environment.

Investigating the evolution of fractures in clay–based ceramics during repeated freeze-thawing cycles using X-ray micro-computed tomography and image analysis

This work presents a study on the fracturing behaviour of a quartz tempered clay-based ceramic subjected to damage in freeze-thaw cycles. X-ray micro-computed tomography (micro-CT) provided high-resolution imaging of the ceramic before and during the freeze-thaw treatment, allowing to analyse a fully water-saturated sample using a special thermal stage designed to keep the sample frozen during analyses. Micro-CT 3D renderings showed the internal features of the specimen (i.e., quartz grain distribution), the increment of fracture count and size, and the detachment of ceramic and/or temper fragments from the edges of the sample over the cycles. Selected 2D micrographs, before and after freeze-thawing treatment, were analysed using the MATLAB toolbox FracPaQ. This software provided detailed data on fracture length, intensity, density, orientation and connectivity, and enabled to interpret the process of fracture initiation and propagation inside the material. These results showed that the temper plays a crucial role in ceramic fracturing behaviour under freeze-thawing conditions, as damage propagation is influenced by quartz grain distribution and orientation within the material. The study described in this work, not only offers new insights into the fracture dynamics of freeze-thawed clay-based ceramics, but also presents a new methodological approach to quantitatively measure fracture damage in porous materials.

Application of General Full Factorial Statistical Experimental Design’s Approach for the Development of Sustainable Clay-Based Ceramics Incorporated with Malaysia’s Electric Arc Furnace Steel Slag Waste

This study aims to optimize the composition (body formulation) and firing temperature of sustainable ceramic clay-based ceramics incorporated with electric arc furnace (EAF) steel slag waste using general full factorial design (GFFD). The optimization is necessary to minimize drawbacks of high iron oxide’s fluxing agent (originated from electric arc furnace, EAF steel slag waste), which led to severe surface defects and high closed porosity issue of the ceramics. Statistical analysis of GFFD including model adequacy checking, analysis of variance (ANOVA), interaction plots, regression model, contour plot and response optimizer were conducted in the study. The responses (final properties of ceramics) investigated were firing shrinkage, water absorption, apparent porosity, bulk density and modulus of rupture (MOR). Meanwhile, the factors employed in experimental parameters were weight percentage (wt.%) of EAF slag added and firing temperature. Upon statistical analysis, GFFD has deduced that wt.% amount of EAF slag added and firing temperatures are proven to significantly influence the final properties of the clay-based ceramic incorporated with EAF slag. The results of conducted statistical analysis were also highly significant and proven valid for the ceramics. Optimized properties (maximum MOR, minimum water absorption and apparent porosity) of the ceramic were attained at 50 wt.% of EAF slag added and firing temperature of 1180 °C.

Optimizacija procesnih parametara keramike na bazi gline sa dodatkom građevinskog otpada i otpada od rušenja

Construction and demolition waste produced in the Republic of North Macedonia remains a major economic and environmental problem because all construction and demolition waste ends up in local dumps or is disposed of in a landfill. The objective of this study was to investigate the influence of the process parameters on the physical and mechanical properties of clay-based ceramics with partial replacement of clay with construction and demolition waste. Determination of the chemical composition of the waste demolition brick using X-ray fluorescence showed that it consisted of different oxides such as SiO2, Al2O3, Fe2O3 and CaO and minor contents of alkaline and earth alkaline oxides. Production of these ceramics was conducted through the consolidation of clay and waste demolition brick with the evaluation of the main process parameters such as sintering temperature [ST], the content of waste demolition brick [WDB] and isothermal period at the final temperature [IP]. The final model equations for density and bending strength dependence of the main process parameters were obtained and presented. The microstructure of the ceramics determined by SEM shows that the waste material is homogeneously dispersed in the clay matrix.

The Influence of Fly Ash on Mechanical Properties of Clay-Based Ceramics

Elastic properties of mixtures of illitic clay, thermal power plant fly ash (fluidized fly ash—FFA and pulverized fly ash—PFA), and grog were investigated during the heating and cooling stages of the firing. The grog part in the mixtures was replaced with 10, 20, 30, and 40 mass% of the fly ash, respectively. The temperature dependence of Young’s modulus was derived using the dynamical thermomechanical analysis, in which dimensions and mass determined from thermogravimeric and thermodilatometric results were used. Flexural strength was measured at the room temperature using the three-point bending test. The following results were obtained: (1) Bulk density showed a decreasing trend up to 900 °C and a steep increase above 900 °C. During cooling, the bulk density slightly increased down to the room temperature. (2) Young’s modulus increased significantly during heating up to ~300 °C. Dehydroxylation was almost not reflected in Young’s modulus. At temperatures higher than 800 °C, Young’s modulus began to increase due to sintering. (3) During cooling, down to the glass transformation, Young’s modulus slightly increased and then began to slightly decrease due to microcracking between phases with different thermal expansion coefficients. (4) Around the β→α quartz transition, radial stresses on the quartz grain altered from compressive to tensile, creating microcracks. Below 560 °C, the radial stress remained tensile, and consequently, the microcracking around the quartz grains and a decreasing Young’s modulus continued. (5) With a lower amount of PFA and FFA, a higher Young’s modulus was reached after sintering. The final values of Young’s modulus, measured after firing, show a decreasing trend and depend linearly on the part of fly ash. (6) The flexural strength measured after firing decreased linearly with the amount of the fly ash for both mixtures.

RECYCLING ROMAN GLASS TO GLAZE PARTHIAN POTTERY

Alkaline glazes were first used on clay-based ceramics in Mesopotamia around 1500 B.C., at the same time as the appearance of glass vessels. The Roman Empire used lead-based glazes, with alkaline natron glass being used only to produce objects of glass. Chemical analysis has had some success determining compositional groups for Roman/Byzantine/early Islamic glasses because of the discovery of major production sites. Parthian and Sasanian glass and glazed wares, however, have been found only in consumption assemblages, which have failed to inform on how they were made. Here we reanalyse compositional data for Parthian and Sasanian glazes and present new analyses for Parthian glazed pottery excavated at the early third century A.D. Roman military outpost of Ain Sinu in northern Iraq. We show that some Parthian glazes are from a different tradition to typical Mesopotamian glazes and have compositions similar to Roman glass. We propose that Roman glass was recycled by Parthian potters, thereby suggesting that as yet undiscovered Mesopotamian glass production centres ordinarily supplied glass for indigenous glazed pottery. Furthermore, if recycling glass to make glazed pottery was extended to indigenous glassware, this may provide an explanation for the paucity of Parthian and Sasanian glass in the archaeological record.

Grain and grain boundaries contributions to dielectric relaxation of the clay-based ceramics

The current paper is a complementary dielectric study on the clay-based ceramics (CBC) to investigate the contribution of grain and grain boundaries to the dielectric relaxations. The dielectric measurements were carried out on the ceramic composed of 50 wt.% clay and 50 wt.% nepheline syenite) over wider ranges of frequency and temperature, using the advanced broadband dielectric spectrometer. Dielectric spectra suggested that the temperature has a significant effect on the electrical microstructure of CBC. They show the existence of two relaxation process associated to the grain boundaries (GBs) and grains in low- and high-temperature regions, respectively. The relaxation process associated with grain is more predominating over GBs relaxation over the temperature range studied. Interestingly, we reported an anomaly feature in dielectric behavior of CBC at − 40 °C at which all dielectric properties changed abruptly.

Boric acid (H3BO3) as flux agent of clay-based ceramics, B2O3 effect in clay thermal behavior and resultant ceramics properties

Ceramic materials were satisfactorily processed through a dry scalable process from binary clay–boric acid (H3BO3) mixtures. Relevant thermal parameters were established by a multitechnique approach that included thermogravimetric, differential thermal analysis, dilatometric analysis and structural and microstructural characterization of fired samples. Both clay and boric acid thermal processes were described and correlated. The experimental textural properties evidenced a porosity decrease with sintering temperature and acid addition in the 1100–1300 °C range. The amount of glass was strongly increased by the boron oxide incorporation, confirming its fluxing capacity. X-ray diffraction, supplemented by Rietveld–Le Bail refinement, verified the presence and thermal evolution of crystalline and glassy phases. The observed microstructure was similar to other clay-based ceramics, with quartz, cristobalite and mullite grains imbibed in the silica-based glassy phase. The observed mullite phase was actually a boron mullite solid solution. Boric acid was confirmed as an adequate boron oxide source. The present study gives information for further clay-based materials design with boron oxide as fluxing agent. The dry route hypothesis was confirmed. Both formulation and firing programs can be optimized. High boron addition (5 mass%) is not recommended due to the observed partial rehydration.

Microstructural Characterization of Clay-Based Ceramics with the Addition of Granite Residues

Million tons of ornamental stones residues are produced every year. Most of this residue is disposed without any kind of processing or treatment. Moreover, disposal occurs without a prospective of reuse or recycling. The incorporation into ceramics is a possible alternative for part of this residue. Clay-based ceramics have high capacity of incorporation of industrial residues. This work aimed to conduct a microstructural characterization of clay-based ceramics with incorporation of granite residues in the composition of the ceramic matrix. Specimens were produced with the addition of 0, 10, 20 and 30 wt. % of granite residues. The specimens were prepared by uniaxial pressing and sintered at temperatures of 1050 and 1200°C. For the microstructural analysis were carried out by scanning electron microscopy and X-ray diffraction. The results indicated that the incorporated ceramics sintered at 1200oC presented higher densification and lower porosity as compared with those sintered at 1050oC.

Granite waste and coffee husk ash synergistic effect on clay-based ceramics

Brazil produces massive amounts of granite sawing waste and coffee husk ash and their inadequate and, often, illegal disposal causes enormous environmental problems. In the past decade, these and other industrial wastes have been intensively studied aiming at determining their potential as alternative raw materials, particularly for the ceramic industry. This work describes research carried out on the joint incorporation of those wastes in ceramic roof tile formulations. The results indicated that the simultaneous use of both materials translates into a very forgivable industrial working range, both composition- and temperature-wise, which, given the technological properties values observed after firing at 1100°C, enables industrial up-grade to wall tile production. As collateral benefits, the use of granite waste and coffee husk ash as alternative raw materials in the manufacture of clay-based products will relieve the stress on feldspars consumption and attenuate waste disposal concerns.

Micromechanics-based estimates on the macroscopic fracture toughness of micro-particulate composites

We investigate the macroscopic fracture toughness of multi-phase materials within the framework of fracture mechanics and micromechanics. Starting with the Eshelby inclusion problem, we provide estimates on the critical energy release. We take into account the elastic and fracture properties of the micro-constituents, the microstructure and the phase volume fractions by considering three schemes: dilute, Mori–Tanaka and generalized self-consistent. In turn, the theoretical model is validated by scratch tests experiments conducted on glass-reinforced polymer composites. We also apply our theoretical framework to porous clay-based ceramics. In both cases, the agreement between experiments and theory is excellent.

Impact resistance of archaeological ceramics: The influence of firing and temper

This work considers technological choices in the manufacture of utilitarian archaeological ceramics, in view of their role in the ceramics' physical properties and affordances. In this paper we present results of an experimental study which examined the influence of processing parameters on mechanical properties of clay-based ceramics. The influence of firing temperature, amount and grain size of aplastic inclusions on a ceramic's response to dynamic loads were determined experimentally, taking into consideration how this compares to the materials' response to static loads. Results show that the fracture strength under quasi-static loading increases with increasing vitrification and decreases with increasing amounts and size of aplastic inclusions. In contrast, while the presence of aplastic inclusions does reduce impact resistance, the amount and grain size of aplastic inclusions do not seem to play a significant role, both in terms of a ceramic's impact strength and fracture energy. This highlights the importance of considering the likely sources of mechanical stresses when assessing the affordances of a ceramic vessel.

Valorization of Solid Petroleum Waste as a Potential Raw Material for Clay-Based Ceramics

Large amounts of waste materials are discarded in the petroleum exploration industry. This work investigates the incorporation of solid petroleum waste (SPW) as a raw material into a clay body, replacing natural clay material by up to 30 wt%. Ceramic pieces were produced at temperatures varying from 700 to 1,100°C. The technological properties of the clay ceramic pieces (e.g., linear shrinkage, apparent density, water absorption, and compressive strength) have been determined. Development of the sintered microstructure was followed by scanning electron microscopy (SEM) and X-ray diffraction analyses. The leaching toxicity of the fired pieces has also been determined. The results showed that the SPW could be used in clay-based ceramics (clay bricks and roofing tiles), in the range up to 30 wt%, as a partial replacement for natural clay material. The leaching concentrations of Ag, As, Ba, Cd, Cr (total), Hg, and Pb of the fired pieces met the Brazilian regulatory requirements. These results suggest that the SPW can be valorized for manufacturing clay-based ceramics, and at the same time, this application can help in reducing the environmental impacts of the petroleum exploration industry.