Advanced Ceramics Research Articles

Efficient single-step mechanosynthesis route of nanostructured Hf0.2Nb0.2Ta0.2V0.2Zr0.2C0.5N0.5 High Entropy Carbonitride Powder

Nowadays high entropy carbides (HECs) are an important group of advanced ceramics. They are composed by at least by five transition metals (TMs) in nearly equiatomic proportion and disordered distributed in the cationic sublattice of face centered cubic structures, with carbon atoms in the octahedral interstitial voids, with general formula (TM1,TM2,TM3,TM4,TM5)C. These HECs belong to the recent novel group of ultra-high temperature ceramics (UHTCs), with superior properties in comparison with the constituent binary carbides. However, the synthesis of those HECs can be modified to develop high entropy carbonitrides, HECNs, where the C are partially substituted by N, to form a solid solution in the anionic sublattice, with expected improved properties as UHTCs, but they are in an incipient state of development. Here, we report the synthesis and deep characterization of a non-previously obtained Hf0.2Nb0.2Ta0.2V0.2Zr0.2C0.5N0.5 HECN, via a facile, single step and reproducible solid-gas reaction mechanosynthesis route. The synthesis was successfully completed in a planetary ball mill device, after 2h of milling time, at 400 rpm and using a ball-to- powder ratio of 60:1 in a pure N2 atmosphere at room temperature. The as-synthesized HECNs powdered showed nanostructured morphology and outstanding high-temperature oxidation resistance up to 1500 °C.

Evolution of ceramic additive manufacturing: A comprehensive survey for high-performance and dental applications

The manufacturing landscape has been altered by additive manufacturing (AdMa), which has surfaced as a versatile and adaptive technology. Notable advancements have been made in the creation of ceramic substances for AdMa procedures. The ceramic components made using AdMa processes show deficiencies concerning their overall performance and mechanical properties. More recently, research has concentrated on improving mechanical properties and effectiveness by optimizing the fabrication procedure by integrating additional post-processing methods and using a material pre-treatment approach. The advancements in AdMa methods for producing high-performance ceramic (H-Perform-C) materials, referred to as advanced ceramics, are reviewed and examined in this article. AdMa methods are classified based on the ASTM's standards and the particular technology used in these procedures is further explained. A comprehensive review is provided, explaining the fundamental principles, mechanical characteristics, merits, drawbacks, practical implementations and constraints associated with each respective technological approach.

Structure-property relationship and emerging applications of nano- and micro-sized fillers reinforced sialon composites: a review

Oxonitridoaluminosilicates (SiAlON) are renowned in advanced ceramics for their exceptional properties: high temperature stability, excellent oxidation resistance, and good wear resistance. Incorporating micro- and nano-sized fillers into SiAlON matrices enhances their properties, yielding SiAlON composite materials with superior mechanical, tribological, and thermal characteristics. This review examines fabrication techniques for producing SiAlON micro/nanocomposites and the structure-property relationships governing their performance across different phase compositions (β, α, X, and O-phases). A comprehensive literature review scrutinized fabrication techniques and structure-property relationships from various databases and scholarly articles. Although SiAlON composites with micro/nano inclusions hold promise across applications, understanding their fabrication processes, structure-property relationships, and potential applications in different fields is crucial. The review highlights diverse fabrication techniques for SiAlON micro/nanocomposites and provides insights into their structure-property relationships. Additionally, emerging applications in structural domains, cutting tools, coatings, corrosion protection, solar cells, LEDs, biomedical realms, and filtration membranes are discussed. This review is a valuable resource for researchers and engineers interested in designing SiAlON products tailored for sophisticated applications. It emphasizes understanding fabrication processes and structure-property relationships to unlock SiAlON-based materials' full potential across industries.

Advancements in multi-material additive manufacturing of advanced ceramics: A review of strategies, techniques and equipment

Ceramics possess notable attributes including excellent wear resistance, exceptional high-temperature strength, superior hardness, and outstanding biocompatibility, rendering them indispensable for the fabrication of key industrial components. Additive manufacturing presents significant benefits such as precise fabrication, design flexibility, and the ability for mass customization. This technology facilitates the creation of intricate structural or functional ceramic components with complex geometries, effectively addressing issues that are inadequately managed by conventional methods, such as the inherent brittleness of ceramics and challenges associated with ceramic machining. As advancements in aerospace, special industry, and biomedical sectors progress, the performance limitations of uniform ceramic materials and structures have emerged as a bottleneck constraining the broadening of their application range. There is a pressing need to transition from single-material ceramic additive manufacturing to multi-material printing. This paper highlights and compares various notable advancements in typical single-material ceramic additive manufacturing. In addition, it delves into the present status of multi-material ceramic additive continuous forming and the development of associated equipment, focusing on different forming mechanisms. Finally, the paper concludes by identifying the primary challenges and research priorities in multi-material ceramic additive manufacturing, and suggests potential directions for future development.

Advanced ceramics with integrated structures and functions: Machine learning prediction and experimental verification

Improving the thermal conductivities and bending strengths of ceramic substrates is crucial for their applicability as key components of integrated chips. Herein, we report the latest study in which the thermal conductivity and bending strength of aluminum nitride (AlN) ceramics were systematically predicted using high-precision prediction model approached with a machine learning (ML) method based on extreme gradient enhancement method (XGBoost). The ML model was used to rank the effects of the process parameters, and SHapley Additive exPlanations (SHAP) was employed to quantify the contributions of different factors. Sintering additives were found to have the predominant influence on the thermal conductivity and bending strength; particularly, those with cationic radii within 0.085–0.105 nm enhance both properties. By using Pr2O3 as the sintering additive and adopting the preparation conditions recommended by the ML model, we prepared AlN ceramics with thermal conductivity as high as 195.63 W m−1 K−1 and bending strength of 371.60 ± 9.31 MPa, thus satisfying the application requirement of high thermal conductivity. The proposed model is also applicable to alumina and silicon nitride ceramics. This study provides a practicable and once-for-all strategy to realize the entire process from the ML prediction design to the preparation of ceramic materials exhibiting superior thermal conductivity and high strength.

Photocatalytic Degradation of Pollutants Using Advanced Ceramics: Materials, Mechanism, Synthesis, and Applications

Photocatalytic Degradation of Pollutants Using Advanced Ceramics: Materials, Mechanism, Synthesis, and Applications

Grain size distribution analysis of MgO and VC inhibited zirconia toughened alumina ceramics using digital image processing

Abnormal grain growth (AGG) of zirconia toughened alumina (ZTA) during sintering decreases phase transformability at critical temperature, leading material failure. The first-ever grain size distribution analysis using image processing in materials science identifies the impact of carbide and oxide inhibitors on tetragonality and grain refinement of ZTA ceramics. Incorporating insoluble vanadium carbide and soluble magnesium oxide inhibitor in ZTA restricts AGG, reducing average grain size of 0.5VC_ZTA by ∼ 86.84% compared to 0.5 MgO_ZTA due to Zener pinning effect of refractory carbide. The inhabitation of dehydroxylation process helps to decrease alumina crystallite size by ∼33.37% in case of VC, thereby increasing the density. Automated analysis using digital image processing makes the process less affected by user bias. A perceptible improvement in micro-mechanical properties through grain refinement of pressure-less sintered 0.5VC_ZTA confirms the structure property correlation of the matrix. This type of analysis has a beneficial aspect towards the fabrication of advanced ceramics with improved properties.

Eco-friendly machining of advanced ceramics: wheel cleaning jet for greenhouse gas reduction

Eco-friendly machining of advanced ceramics: wheel cleaning jet for greenhouse gas reduction

Additive manufacturing of sensor prototype based on 3D-extrusion-printed zirconia ceramics

Additive manufacturing of ceramics has attracted large interest due to its unique ability to rapidly prototype, low cost, and increased geometric complexity. Material extrusion technique is often considered for processing and shaping fine and dense ceramic structures because of the high solid loading in ink. In this work, 8 mol.% yttria-stabilized zirconia ink with 70 wt% ceramic loadings was prepared to print zirconia samples in horizontal and vertical directions, following two different filament orientations: 0/90° and ±45°. The study's main objective was to evaluate printing design influences on mechanical properties. This was assessed through flexural testing and digital image correlation analysis. Experimental findings showed that samples printed horizontally with ±45° filament orientation displayed the highest strength. A detailed inspection of fracture surfaces revealed that printing defects were the critical failure location sites formed after sintering and intimately related to printing design issues. After that, a conductive sensor was integrated into the surfaces of 3D-printed specimens by screen-printing silver-based conductive ink to analyze the structural health of zirconia samples. The sensing capabilities of printed conductive patterns were investigated using the four-point bending tests. The results demonstrated that the electrical resistance of the printed silver patterns increased as the applied load on zirconia substrates rose. It indicates that hybrid material extrusion and screen printing techniques are favored ways to manufacture sensors for structural detection of advanced 3D-printed ceramics.

Holistic Characterization of MgO-Al2O3, MgO-CaZrO3, and Y2O3-ZrO2 Ceramic Composites for Aerospace Propulsion Systems

Aerospace propulsion systems are among the driving forces for the development of advanced ceramics with increased performance efficiency in severe operation conditions. The conducted research focused on the mechanical (Young’s and shear moduli, flexural strength, hardness, and fracture toughness), thermal (thermal conductivity and coefficient of thermal expansion), and electric (dielectric properties) characterization of MgO-Al2O3, MgO-CaZrO3, and stable YSZ ceramic composites. The experimental results, considering structural and functional traits, underscore the importance of a holistic understanding of the multifunctionality of advanced ceramics to fulfill propulsion system requirements, the limits of which have not yet been fully explored.

Physics-based neural network as constitutive law for finite element analysis of sintering

In the sintering of advanced ceramics, a digital twin consisted of a finite element model can predict the final shape and microstructure of a sintered ceramic. However, to minimise uncertainties, it is essential to continually update the mechanical properties in the digital twin using data collected from the manufacturing process. One promising approach for achieving this is through artificial neural networks (ANN). This study introduces a machine learning strategy to update the constitutive behaviour of advanced ceramics in finite element analysis of sintering deformation. A major challenge in implementing machine learning in material processing is the huge amount of data required by the training and validation of an ANN, which are often unavailable or incomplete in a real manufacturing process. This study demonstrates that the data requirement can be reduced by employing a two-step training technique. Firstly, the ANN is trained using a nonlinear constitutive law, which describes a general relationship between the strain rates and stresses. Subsequently, the weights and biases of the ANN are transferred for the retraining using limited experimental data for an actual ceramic. It is shown that such approach can successfully capture the nonlinear constitutive behaviour of fine-grained alumina without demanding for large amount of experimental data. A case study is provided, highlighting the feasibility of implementing the ANN in a commercial finite element package, to replace the constitutive law and predict the shrinkage and distortion of a sintering part. In particular, the sintered dumb-bell shape part, simulated using the retrained ANN, showed grain size and relative density that markedly different from those using the nonlinear constitutive law. It is important to note that the proposed methodology is generic and can be used to create ANNs to replace constitutive laws in finite element analysis in digital twins for a wide range of other engineering processes.

Advanced Ceramics with Dual Functions of Healing and Decomposition.

This study developed advanced ceramic materials with both healing and decomposition functions using a metastable product generated under superheated steam. The developed composite material comprises ZrC particles dispersed in a yttria-stabilized zirconia (YSZ) matrix. After introducing a surface crack of approximately 120 μm on the composite specimen, it showed a complete strength recovery rate after one hour of heat treatment under superheated steam at 400 °C, while it exhibited a decomposition behavior after one hour of heat treatment in air at 400 °C. The XRD analysis of the heat-treated specimens showed that the final product was monoclinic ZrO2 under both steam and air conditions. In other words, full strength recovery in superheated steam was achieved by a chain reaction involving metastable intermediate products derived from H2O, unlike the reaction in air.

Effects of processing conditions on flash sintering of commercial ZrN

AbstractFlash sintering (FS) is a potentially rapid and low‐cost manufacturing technique for advanced ceramics. There are still many unknowns about ceramic FS, especially for highly conductive high‐temperature ceramics (HTC), which often display decreased bulk conductivity with increasing temperature. This study qualitatively characterizes the flash behavior of highly conductive HTC materials using zirconium nitride (ZrN) as an example. The effects of processing parameters (e.g., DC voltage/electrical field strength, voltage ramp rate, post‐flash holding time, mechanical pressure, sample milling, and choice of electrode materials) on ZrN flash behavior are also qualitatively studied and linked to samples microstructure and hardness. It is observed that best densification was achieved using 5 min Spex‐milled ZrN powder under 25 MPa of applied pressure and constant 8 V DC. The potential mechanism for ZrN FS and the similarity and difference from FS of conventional oxides like YSZ have been proposed based on experimental observations, and the directions for future research are also pointed out.

Viscoelastic Paste-Based Ceramic vat Photopolymerization: Recent Achievements and Future Developments

Ceramic vat photopolymerization (VPP) enables the fabrication of complex components with excellent properties and high precision. However, compared with metals and polymers, the industrial application of ceramic VPPs remains relatively limited. This can be attributed to the challenges associated with ceramic feedstock printability, the complexity of the printing process, insufficient performance evaluation, and service verification. To overcome these limitations, the design of a viscoelastic paste and corresponding VPP strategies offer a promising solution. This paper presents a review of the research on the state of viscoelastic ceramic paste-based VPP. The main technical aspects, including the paste design, support strategies, green-body cleaning, and subsequent post-treatment, are discussed. Furthermore, representative applications of VPP for various types of advanced ceramics are surveyed. This review also highlights the technical challenges involved and provides suggestions for addressing these issues. Finally, future directions for promoting the additive manufacturing of advanced ceramic components with enhanced efficiency and reliability are discussed.

Research Progress and Application Prospect for Advanced Ceramic Materials in Helicopter Special Structures

Research Progress and Application Prospect for Advanced Ceramic Materials in Helicopter Special Structures

Advancing Electric Flight through Innovative Materials in Aerospace Propulsion Systems

The advent of electric aircraft heralds a transformative era in aviation, offering a sustainable alternative to conventional aircraft that significantly contribute to carbon emissions. This paper discusses the application of advanced materials in overcoming the technical hurdles associated with electric propulsion systems, focusing on their application in airframe construction, electrical conductors, thermal management, and battery technology to enhance the performance and sustainability of electric aircraft. Advanced composites like carbon fiber reinforced polymer (CFRP) are explored for their potential to reduce aircraft weight and improve mechanical properties. The paper also addresses the challenges of thermal management in electric propulsion systems, highlighting the use of phase change materials (PCMs) and advanced ceramics for efficient heat dissipation. Furthermore, the exploration of high-energy-density cathode materials, innovative anode materials, and solid-state electrolytes is discussed in the context of developing lightweight, high-capacity batteries for electric aircraft. Despite the promising advancements in material science and the potential benefits of electric aviation, the paper acknowledges the existing challenges, including the high cost of advanced materials, the need for improved energy storage solutions, and the environmental impact of material production.

Straightforward Design Strategy toward 3D Near-Net-Shape Stoichiometric SiC Parts.

Fused deposition modeling (FDM), traditionally reserved for thermoplastics, is modified here with a granule-based extrusion head to be extended to advanced nonoxide ceramics via a straightforward design strategy that considers the shaping opportunities and the chemical richness offered by preceramic polymers. Specifically, 3D near-net-shape stoichiometric silicon carbide (SiC) objects are designed by manipulating the key features of a commercially available polycarbosilane (fusibility, high carbon content, relatively high SiC yield). In the early stage of the process, the carbon-rich polycarbosilane is first mixed with Si and SiC fillers and then thermolyzed at 120 °C to increase polymer branching while offering tailored rheological properties during the subsequent extrusion process at 90 °C and adequate shape retention once extruded. This allows for the design of tailored and complex 3D complex polycarbosilane-based architectures with features down to 400µm. Polymer-based parts are further converted into 3D stoichiometric SiC objects with quasi-near-net-shape-a volume shrinkage reduced to 9.1% is measured-by heat treatment at a temperature as low as 1400 °C (argon flow). Given the flexibility to tune the preceramic polymer chemical and rheological properties, a new combined design approach is leveraged to generate bespoke advanced ceramics with a high freedom in geometry complexity.

Enhancing the Properties of Yttria-Stabilized Zirconia Composites with Zeolitic Imidazolate Framework-Derived Nanocarbons.

Ceramic matrix composites (CMCs) reinforced with nanocarbon have attracted significant interest due to their potential to enhance mechanical, thermal, and electrical properties. Although the investigation of carbon-based materials such as graphene and carbon nanotubes as additives for advanced ceramics has been widespread, the utilization of metal-organic framework (MOF)-derived nanocarbons in CMCs remains largely unexplored. We extended our previous proof-of-concept investigations by demonstrating the effectiveness of a different type of MOF-derived carbon as a reinforcing phase in an alternative ceramic matrix. We employed spark plasma sintering (SPS) to consolidate yttria-stabilized zirconia (YSZ) and zeolitic imidazolate framework (ZIF-67) powder blends at 1300 °C and a uniaxial pressure of 50 MPa. YSZ serves as the ceramic matrix, whereas ZIF-67 serves as the nanocarbon source. The composite exhibits a highly significant improvement in fracture toughness with an increase of up to 13% compared to that of the YSZ monolith. The formation of ZIF-derived nanocarbon interlayers is responsible for the observed enhancement in ductility, which can be attributed to their ability to facilitate energy dissipation during crack propagation and inhibit grain growth. Furthermore, the room-temperature electrical conductivity of the sintered samples demonstrates a substantial improvement, primarily due to the in situ formation of nanocarbon-based fillers, reaching an impressive 27 S/m with 10 wt % ZIF-67 content. Based on the results, it can be inferred that the incorporation of in situ MOF-derived nanocarbons into CMCs leads to a substantial improvement in both the mechanical and electrical properties.

The effect of different anions on the crystallization course of α‐Al2O3 powder in hydrothermal method

Abstractα‐Al2O3 powder with excellent sintering properties plays an irreplaceable role in advanced ceramics. However, the preparation of α‐Al2O3 at low temperature still remains a grand challenge. Herein, aluminum sulfate, aluminum nitrate, and aluminum chloride are used as raw materials for α‐Al2O3 synthesis. In general, the Al3+ will be hydrolyzed to form AlOOH during the hydrothermal process. But SO42− reacted with Al3+ and OH− to form Al4(OH)10SO4 during the hydrothermal process. During the calcining process, the transition temperatures from AlOOH to α‐Al2O3 were 1100°C, which can be summarized as follows: AlOOH → γ‐Al2O3 → θ‐Al2O3 → α‐Al2O3. Meanwhile, Al4(OH)10SO4 converted into pure α‐Al2O3 at only 1050°C, due to the direct conversion from γ‐Al2O3 to α‐Al2O3. This spherical α‐Al2O3 was made up by completely uniformed small particles of about 10–20 nm. Finally, an Al2O3 ceramic with 98.07% of theoretical density and .01% water absorption rate was obtained at a temperature of 1600°C. This work offers an intriguing solution toward the development of Al2O3‐based advanced ceramics.

Multiwalled carbon nanotubes as hard templates to yield advanced geopolymer-based self-assembled nanostructured ceramics

Novel multifunctional construction materials are needed to promote resilient infrastructure in the face of climate change and extreme weather. Nanostructured materials such as geopolymer reinforced with carbon-based nanomaterials are a promising way to reach that goal. In recent years, several studies have investigated the influence of nanomaterials on the physical properties of geopolymer composites such as compressive strength and fracture toughness. Yet, a fundamental understanding of the influence of nanomaterials on the nanoscale and micron-scale structure has been elusive so far. Our research objective is to understand how multiwalled carbon nanotubes (MWCNT) can help tailor the microstructure of geopolymers to yield architected multifunctional nanocomposites. We synthesized geopolymer nanocomposites reinforced with 50-nm thick multiwalled carbon nanotubes with mass fractions in the range of 0.1 wt%, 0.2 wt%, and 0.5 wt%. Our major finding is that MWCNTs act as hard templates that promote geopolymer formation via self-assembly. Geopolymer nanoparticle growth is observed along the walls of MWCNTs. A refinement in grain size is observed: increasing the fraction of MWCNTs by 0.5 wt% leads to a reduction in grain size by 54%. Similarly, increasing the mass fraction of MWCNTs leads to a densification of the geopolymer matrix as demonstrated by the Fourier transform infrared spectroscopy results and the statistical deconvolution analysis. Mercury intrusion porosimetry shows a nanoscale tailoring of the pore size distribution: a 26% decrease in porosity is observed as the fraction of MWCNTs is increased to 0.5 wt%. As a result of these nanoscale structural changes, a greater resistance to long-term deformation is observed for MWCNT-reinforced geopolymers, as the creep modulus increases both locally and macroscopically. At the macroscopic level, a 42% increase in the macroscopic logarithmic creep modulus is observed as the fraction of MWCNTs is increased to 0.5 wt%. These findings and the supporting methodology are important to understand how to manipulate matter below 100 nm. This research also paves the way for the design of resilient infrastructure materials with tailored microstructure and mechanical properties.