Ceramic Processing Research Articles

Band Gap Engineering of Semiconductors and Ceramics by Severe Plastic Deformation for Solar Energy Harvesting

Band Gap Engineering of Semiconductors and Ceramics by Severe Plastic Deformation for Solar Energy Harvesting

Manufacturing and decorating cardial pottery: shell tools at the Neolithic site of Cabecicos Negros (Vera, Almeria, Spain)

Traditional research approaches on pottery production based on typological and morphometric classifications have changed in favour of new lines of research. One of them is based on the study of the technological equipment used in ceramic manufacturing processes. For example, ethnographic evidence shows the use of shell tools as technological equipment in different phases of ceramic production. In this study, the methodology of use-wear analysis has been applied to the archaeomalacological material from the Neolithic site of Cabecicos Negros (Andalusia, Spain) to establish if the shells were used as work tools. This analysis has been completed with the development of an experimental program composed of two analytical and one prospective experiments, carried out to provide new data about the cardial decorative technique and to define the use-wear traces that appear on the active area of the shells after their technological use. The results obtained in this investigation show the use of shells in different stages of pottery production. On the one hand, during the modelling and regularization phase of the ceramic surface and, on the other hand, during the cardial decorative phase. In this way, through this work, it has been possible to establish that the archaeological site of Cabecicos Negros was a pottery production center where domestic pieces were made during its Neolithic occupation. In addition, these findings reaffirm the importance of shells in ceramic manufacture during the Neolithic period, mainly in terms of the technical process linked to the cardial-type of ceramic decoration.

Piezoelectric hysteresis and relaxation processes in ferroelectric ceramics in weak electric fields

The processes of piezoelectric relaxation and hysteresis in ferroelectric piezoelectric ceramics based on the lead zirconate-titanate system are studied in the region of weak electric fields. An analysis of the field and time dependences of the complex piezoelectric modulus |d31| obtained by processing sequentially measured piezoresonance spectra of the radial vibration mode of thin piezoceramic disks using the piezoresonance spectrum analysis method and program (PRAP) was carried out. A physical interpretation of the results obtained is proposed.

BaTiO3 Nanoparticle Interfaces in Contact: Ferroelectricity Drives Tribochemically Induced Oxygen Radical Formation.

Chemical transformations at metal oxide interfaces that are triggered by mechanical energy set the basis for applications in the fields of tribo- and mechanochemistry, ceramic and composite processing, and piezoelectric devices. We investigated the early stages of tribochemically initiated radical chemistry of structurally well-defined TiO2 and BaTiO3 nanoparticles in argon or in oxygen atmosphere. Electron paramagnetic resonance spectroscopy enabled the determination of the chemical nature and concentration of paramagnetic surface species which form upon uniaxial powder compaction at room temperature. Trapped hole centers (O-) as well as trapped or scavenged electrons (Ti3+ or O2-, respectively) were analyzed as products of mechanical surface activation. For ferroelectric BaTiO3 nanoparticles, we found that the spontaneous polarization effects of the oxide lattice increase the yield of paramagnetic surface species by a factor >20 as compared to paraelectric TiO2 nanoparticles. Comparison with UV excitation experiments, where the energy required to drive the corresponding charge separation phenomena is hν ≥ 3.2 eV, indicates that the paramagnetic species that originate from uniaxial powder compaction in the dark result from mechanically induced surface redox processes that are supported by local flexoelectric potential differences.

Fabrication of ZrO2 Armor Ceramics by 3D Printing Accompanied with Microwave Sintering.

Ceramic armor protection with complex shapes is limited by the difficult molding or machining processing, and 3D printing technology provides a feasible method for complex-shaped ceramics. In this study, ZrO2 ceramics were manufactured by 3D printing accompanied with microwave sintering. In 3D printing, the formula of photosensitive resin was optimized by controlling the content of polyurethane acrylic (PUA) as oligomer, and the photosensitive resin with 50% PUA showed excellent curing performance with a small volume shrinkage of 4.05%, media viscosity of 550 mPa·s, and low critical exposure of 20 mJ/cm2. Compared to conventional sintering, microwave sintering was beneficial to dense microstructures with fine grain size, and microwave sintering at 1500 °C was confirmed as an optimized sintering process for the 3D-printed ZrO2 ceramics, and the obtained ceramics showed a relative density of 98.2% and mean grain size of 2.1 μm. The PUA content further affected the microstructure and mechanical property of the ZrO2 ceramics. The sample with 10%~40% PUA showed some pores due to the low viscosity and large volume shrinkage of photosensitive resins, and the sample with 60% PUA exhibited an inhomogeneous microstructure with agglomeration, attributed to the high viscosity of photosensitive resins. Finally, the ZrO2 ceramics via 3D printing with 50% PUA showed superior mechanical properties, whose Vickers hardness was 3.4 GPa, fracture toughness was 7.4 MPa·m1/2, flexure strength was 1038 MPa, and dynamic strength at 1200 s-1 was 4.9 GPa, conducive to the material's employment as armor protection ceramics.

Cold Sintering of LLTO Composite Electrolytes for Solid‐State Lithium Batteries

AbstractSolid‐state batteries have the potential for higher energy densities and enhanced safety when compared to conventional lithium‐ion batteries. The perovskite‐type Li3xLa2/3–xTiO3 (LLTO) is an attractive ceramic electrolyte due to its high ionic conductivity, broad electrochemical stability window, and thermal and chemical stability. The conventional sintering process for ceramics, typically performed at high temperatures (~1000 °C), poses a critical bottleneck for integrating solid electrolytes with active electrode materials. In this study, Li0.29La0.57TiO3/polypropylene carbonate (PPC) composite electrolytes containing lithium perchlorate (LiClO4) were densified using cold sintering at 125 °C. The resulting LLTO‐based composite electrolytes exhibit relative densities above 80 % and ionic conductivities exceeding 10−4 S cm−1 at room temperature. The symmetric Li/LLTO‐PPC‐LiClO4/Li cell with PVDF interlayers achieves a high critical current density of 1.8 mA cm−2 at room temperature. Solid‐state lithium batteries fabricated with LLTO composite solid electrolytes deliver a high discharge capacity of 151 mAh g−1 at 0.1 C and 135 mAh g−1 at 0.2 C. Our approach, which integrates ceramic and polymer materials, produces composite electrolytes with superior properties, highlighting the potential of cold sintering for advancing solid‐state batteries.

An advanced retrieval-augmented generation system for manufacturing quality control

The rise of Large Language Models (LLMs) with generative artificial intelligence has revolutionized the development of knowledge-based systems, enabling intuitive interactions through natural language. This paper explores the implementation of an advanced Retrieval-Augmented Generation (RAG) system, designed to improve manufacturing quality control by utilizing the capabilities of LLMs, particularly OpenAI’s GPT models. We focus on the ceramic tile manufacturing process, where the system retrieves and analyzes specialized bibliographic sources to diagnose defects and propose solutions. In addition to core RAG functionalities, the system incorporates tailored pre-processing and post-processing mechanisms to optimize document retrieval and response generation. The system’s effectiveness in solving quality issues is demonstrated through its application in identifying defect causes and generating actionable solutions, significantly improving non-conformities management. This approach not only streamlines troubleshooting but also enhances the quality control system, providing a comprehensive, scalable tool for manufacturers.

Understanding the ultrashort laser microwelding process of ceramics to metals by numerical and experimental investigations

Ultrashort laser microwelding is an advanced technology with significant potential and benefits for welding dissimilar materials, including ceramics and metals. Details of the microwelding process involving ceramics and metals with ultrashort lasers remain somewhat unclear, especially regarding phase transformation and the underlying mechanism of joint formation. In this study, we utilized the ultrashort laser microwelding technique to join sapphire and Invar alloy. We have developed a predictive numerical model to calculate the interfacial temperature during the laser irradiation process. The relative contributions of heat diffusion, heat radiation, and heat accumulation in the welding process of two materials were investigated under single and multiple pulses. Upon implementing laser pulse energies of 35, 40, and 50 μJ, the maximum temperatures of sapphire were 3027.8, 4179.89, and 4533.30 K, respectively. The maximum temperature of the Invar alloy exceeded the vaporization temperature (3223.15 K). This resulted in various phase transformations, including evaporation, ionization, and melting, that occurred on both substrates. These transformations also caused the intermixing and diffusion of materials. It then resulted in the formation of the final joint. Based on the findings, we aim to provide a more comprehensive understanding and practical applications of the ultrashort laser microwelding technique.

Temperature During Convective Drying of Thin Flat Wet Materials

. The basic laws of the kinetics of drying thin flat materials during the period of drop in the drying speed are outlined. A method for calculating the average integral temperature of wet material on the basis of the relative temperature coefficient of drying is presented. Experimental data are processed based on the relative drying rate in the drying processes of ceramics, asbestos, and woolen fabric. A formula for calculating the average temperature is proposed. The solution of the differential equation of thermal conductivity for a wet plate during the drying process (namely during the period of drop in the drying speed) under boundary conditions taking into account the conditions of drying is given. The calculation of the heat transfer coefficient is given, too. Based on the study of various sources and processing of experimental results, formulas for calculating the thermal conductivity coefficient of wet materials have been presented. The analytical solution of the problem confirmed that during convective drying in low-intensity processes of the second drying period, the temperature change with a decrease in moisture content turns from an exponential dependence smoothly into a linear one, which is completely consistent with the experiment. A comparison of the temperature calculation by the experimental formula with the results of analytical solutions has been presented. A sufficiently reliable coincidence of experimental and calculated analytical values of temperature for the period of drop in speed drying of ceramics, asbestos, and fabric is obtained.

Material removal mechanism in Fenton based AlN ceramic substrate polishing process

Material removal mechanism in Fenton based AlN ceramic substrate polishing process

Influence of the binder composition on the water debinding properties of a PVB-PEG-alumina feedstock for the fused deposition of ceramic process

Influence of the binder composition on the water debinding properties of a PVB-PEG-alumina feedstock for the fused deposition of ceramic process

High-temperature shrinkage compensation of cesium-based geopolymer: Synergistic effects of kyanite decomposition, ceramization and phase transformation

Cesium-based geopolymers and their ceramization product, pollucite, exhibit excellent heat resistance and considerable potential as engineering materials for high-temperature environments. However, the substantial shrinkage of cesium-based geopolymer during the ceramization process hinders its wide application. In this study, cesium-based geopolymer composites were prepared and evaluated on their shrinkage compensation, with the addition of reinforcing phases of kyanite or corundum. Compared with the sample with the addition of corundum, the linear shrinkage of the sample with the addition of kyanite after heat treatment at 1400 °C was reduced from 15.30 % to 6.28 %, showing a decrease by 54.89 % in linear shrinkage. There was no reaction between kyanite and geopolymer at room temperature, and the ceramization process of the cesium-based geopolymer was not altered either. The decomposition of kyanite at 1200–1400 °C during heat treatment produced mullite and silica, which expanded the volume by 18 %. This compensated for the shrinkage that occurred during the subsequent processes of ceramization and sintering of geopolymer. Mullite and silica further reacted with CsAlSiO4-ANA (having the same cubic ANA type zeolite framework as pollucite) to form corundum and pollucite (CsAlSi2O6) at 1300–1400 °C, during which the average size of pollucite grains increased from 1.82 μm to 4.34 μm, with an increase of 238.46 %. The reaction in this stage prevented the volatilization of cesium in the high temperature, and the increase of pollucite particle size reduced the shrinkage and porosity. This study cast the light on the design and preparation of low-shrinkage, ceramizable, geopolymer composites by synergistic effects of kyanite decomposition, ceramization and high-temperature phase transformation.

Lowering hot isostatic pressing temperature of ultrafine‐grained MgAl2O4 transparent ceramics by two‐step pre‐sintering

AbstractCubic‐phase magnesium‐aluminum spinel (MAS) has attractive optical, mechanical, and thermal properties and has been widely used as transparent ceramics in a number of applications. However, the processing of MAS transparent ceramics typically requires pre‐sintering and hot isostatic pressing (HIP) both at very high temperatures (e.g., above 1600°C) over an extended time, which coarsens the microstructure thus impairing mechanical properties. There is an urgent need to lower the sintering temperature while maintaining high optical transparency. Here we reported new progress in combining two‐step sintering in the pressureless pre‐sintering step and low‐temperature HIP in the post‐treatment step, using high‐quality green bodies produced by pressure filtration. With this strategy, high‐quality MAS transparent ceramics are delivered. The main benefits include 200°C lower HIP temperature, a 33% smaller average grain size of 350 nm, and a higher hardness of 14.8 GPa. Such a method could be extended to many other transparent ceramics.

Effects of La2O3 on sintering of MgO-CaO ceramics: Molecular dynamic simulation and experiments

The mechanism of the additive La2O3 on the sintering process of MgO-CaO ceramics was investigated by molecular dynamics simulation, and the interfacial reaction and nanoparticles sintering models were established. The simulations demonstrated that MgO and CaO dissolve into La2O3 crystals, creating O2- vacancies around Mg2+ and Ca2+. These vacancies significantly increase the diffusion rate of ions. Meanwhile, the La2O3 shifts the sintering driving force from reducing internal energy to increasing entropy, thereby enhancing the sintering degree of nanoparticles. However, excessive La2O3 introduction prolongs solid solution reaction times and impedes particle-particle contact, negatively affecting sintering densification. Experimental results show that the density of MgO-CaO ceramics initially increases with the addition of La2O3, reaching a peak of 3.43 g/cm³ at 0.3 mol%, before decreasing. This result aligns with the model's predictions regarding the effect of La2O3 addition. Moreover, the established models offer reference for selecting sintering aids in composite ceramics production.

(Invited) Processing, Mechanics, and Electrode Structure for All-Solid State LLZO Batteries

LLZO (Li7La3Zr2O12) and related garnet materials are primary candidates for the electrolyte and electrode scaffold of all-solid state lithium batteries. LLZO is a ceramic oxide with a wide voltage stability window, good conductivity at room temperature, and chemical compatibility with a wide variety of electrode active materials. Implementation of LLZO in full cells with high energy density is challenging, however, due to Li loss during sintering, reaction with transition metal cathodes at elevated processing temperatures, high volumetric density that limits cell energy density, brittle mechanical failure, and lithium intrusion into the electrolyte during cell operation at high current density. This presentation will summarize our efforts to address these issues through advancements in processing, mechanical properties, electrode structure, and composite electrode material selection.To enable high energy density, it is desirable to utilize a thin (<100 μm) LLZO electrolyte layer. High conductivity of the thin electrolyte is maintained by adding sacrificial lithium carbonate, which compensates for lithium evaporation during sintering. Adding MgO prevents abnormal grain growth and maintains the desired fine grain structure, leading to a ~70% increase in fracture strength. Preparing a thin, flexible green ceramic sheet via tapecasting allows the electrolyte to be laminated to a porous LLZO electrode scaffold, or shaped via texturing prior to sintering. Scaffolds are prepared by high shear compaction, phase inversion, freeze tape casting, and other processing techniques based on scalable tape casting. In the case of texturing, surface features are impressed into the green LLZO tape and the additional surface area of the sintered LLZO surface decreases interfacial resistance and increases critical current density from 0.2 to 0.5 mA/cm2.Utilizing these optimized ceramic fabrication processes, solid state cells are prepared with ~80 μm thick LLZO electrolyte, no added liquid electrolyte, and no exogenous pressure. A catholyte comprising organic ionic plastic crystal and a mixture of lithium salts is melt-processed to achieve good wetting and interfacial contact between the rigid LLZO and NMC cathode active material. This cell design achieves ~180 mAh/g and stable cycling for >100 cycles at room temperature. Efforts to scale up the cell size and improve rate capability will also be discussed.

High Throughput Li-Ceramic Battery Electrolyte Property Optimization Based on Efficient Sample Space Exploration

Solid-state batteries (SSBs) are safer, cheaper, and higher energy density alternatives to conventional Li-ion batteries, of which the global production capacity has reached 150 GWh/year. However, development of new materials and their optimization to predicted ideal structure-property characteristics can typically take >10 years of capital-intensive research to find the best solidification and dopant strategies. Typical solid-state manufacture considers high temperature synthesis based on powder sintering for Co-free cathode material integration, which is time and labor intensive, produces a large CO2 footprint, and incurs high costs. In contrast, wet-chemical fabrication methods like sequential deposition synthesis (SDS) can realize faster achievements in direct liquid precursor to solidified electrolyte translation. Li7La3Zr2O12 (LLZO) is a promising solid electrolyte that has seen much interest in the battery field and has been demonstrated to be manufacturable with thickness between 1-15 µm via SDS. In this work, we demonstrate for the first time a high throughput experimental platform, computer-controlled SDS deposition system to rapidly fabricate LLZO and alter its structure-property characteristics with precursor and deposition modulations. Dopant amounts are adjusted in real time to easily control film composition and test a wide parameter field. In-situ annealing is achieved via an advanced heating element implemented directly into the chamber. Raman spectroscopy exhibits sufficient sensitivity to the phases under study, is a contactless and nondestructive technique, and has a low data acquisition time allowing for high-volume analysis coupled to high throughput synthesis. A quantification of Raman spectra is presented to supply a Bayesian optimization framework for greater experimental efficiency by selecting interesting regions by phase and other 2nd order characteristics of the experimental space to selectively sample for desired phases and, importantly, their high-dimensional phase boundaries. The capabilities of the new experimental framework are discussed for further work in accelerated solid-state ceramic materials discovery and we employ here careful considerations on the synthesis methods and computational approaches chosen towards the plethora of ceramic process options. This framework is capable of rapidly synthesizing solid-state electrolytes with a variety of composition and deposition conditions to optimize their properties so they can be rapidly deployed in next-generation batteries in significantly shorter times than traditional methods allow.

Mechanical Behavior of Thin Ceramic Laminates on Central Incisors.

Restorative dentistry often uses ceramic laminate veneers for aesthetic anterior teeth restorations due to their natural appearance and minimal invasiveness. However, the understanding of their clinical performance and how ceramic microstructure and processing affect longevity is limited. Objective: This study aimed to address this gap by determining the mechanical behavior, fracture load, and failure modes of CAD-CAM processed laminate veneers made of either lithium-disilicate-based glass ceramic (IPS e.max CAD) or feldspathic porcelain (Vita Mark II). It also aimed to develop a mechanical cycling methodology capable of determining the lifetime and failure modes of thin ceramic laminate veneers. Materials and Methods: Eighteen human maxillary central incisors were used to create the specimens. Minimal enamel preparation was required to ensure the proper adaptation of the thin ceramic laminates. Ceramic laminates made from lithium disilicate and feldspathic porcelain (Vita Mark II) were produced via CAD-CAM, with the final thicknesses less than 0.5 mm, then cemented with resin cement. Results: The mean fracture load for the glass ceramic was 431.8 ± 217.9 N, while for the porcelain, it was 454.4 ± 72.1 N. Failure modes differed considerably: porcelain showed more chipping, while lithium disilicate was associated with tooth structure failure. Conclusion: The material used did not significantly affect the fracture load of thin ceramic laminates in static tests. However, failure modes differed considerably. It was not possible to determine a set of mechanical cycling parameters that could establish the fatigue properties of thin ceramic laminates, as the maximum number of cycles reached was 536,818.

Preparation of lightweight, honeycomb-like, wideband microwave absorbing SiC/C aerogels via carbothermal reduction

Based on the micro-nano scale designs for absorbing materials, analyzing the influence of microstructures on absorbing properties is a feasible strategy to achieve efficient lightweight broadband electromagnetic wave absorbers. In this work, the silicon-containing arylacetylene resin, serving as a ceramic polymer precursor, is employed to coat SiO2 gel. Subsequently, the PSA/SiO2 aerogel underwent carbothermal reduction and the polymer-derived ceramics process, transforming it into a SiC/C aerogel. This SiC/C aerogel exhibits a low density of 0.2 g/cm³ and a high porosity of 68 %. The rich morphology of SiC/C aerogel is conducive to both interfacial polarization and multiple scattering, resulting in excellent impedance matching and attenuation. With a reflection loss of −52.6 dB and an effective absorption bandwidth of 6 GHz, SiC/C aerogels also achieve effective absorption in both the X and Ku bands. These results may thus be of great significance in guiding the design and mechanism investigation of high-performance.

Femtosecond laser ablation of zirconia-based ceramic materials: From ablation mechanism to modelling of large-scale processing

Femtosecond laser ablation can offer a promising solution for precise and efficient processing of zirconia-based ceramics taking advantage of ultrafast photon-material interaction. However, due to the nonlinear nature of the process, the selection of the laser parameters in 3D processing is complicated, often leading to reduced efficiency or low material integrity. Here, we address this problem through static (D2) and dynamic (grooving) testing, establishing a comprehensive understanding of the femtosecond ablation behaviour of zirconia on micro- and macro- scales. The ablation threshold of zirconia shows a significant dependence not only on the irradiation history but also on the material temperature. While the processing efficiency can be increased, a critical interpulse duration or a high heat input can facilitate a melting regime, negating the advantages of pulsed laser ablation. Morphological evolution of the surface impacts the ablation behaviour further affecting the process efficiency. Additionally, zirconia semitransparency leads to the formation of nanopores compromising residual material integrity. Based on the analysis of these elementary ablation events, we built an ultrafast computational model, simulating the surface evolution during femtosecond laser ablation with various beam-surface kinematics. Validating the model on a 3D dental crown surface underscores its potential for computer aided design-manufacturing frameworks given its efficiency.

Rapid high-precision machining of LTCC utilizing water-jet guided laser technology: Expanding the horizons of functional ceramic processing

Low temperature co-fired ceramic (LTCC) has become the ideal substrate material for the next generation of circuit boards. However, due to their brittle nature, high-precision cutting of LTCC without edge breakage and heat-affected zones has been a significant challenge. In this paper, water-jet guided laser (WJGL), as a new machining method for brittle material, was employed to process LTCC and result in high-quality cutting. LTCC substrates with a thickness of 1.6 mm were processed without any movement of the z-axis cutting head, thus maximizing cutting efficiency. The grooves with a maximum aspect ratio of 25.6, a taper angle of 0.2° and a minimum cross-sectional roughness of 5.61 µm were obtained after optimization (laser power of 20 W, cutting speed of 5 mm/s and water pressure of 30 MPa). Furthermore, the results show that by gradually increasing the laser power up to 32 W, the molten layer and debris at the edges of the microgroove cuts were significantly reduced, resulting in extremely high straightness. In addition, the oxidation mechanism of the microgrooves was thoroughly investigated by material analysis. Compared with conventional laser processing method, WJGL demonstrates superior cutting quality and higher cutting efficiency, thereby favoring the integration and miniaturization of multifunctional circuits. Overall, our results reveal the considerable potential of the WJGL for processing highly brittle materials.