International Journal of Applied Ceramic Technology最新文献

The development of cost-effective, nonradioactive zirconium (Zr)-free opaque glazes represents a critical objective for sustainable ceramic manufacturing. This study successfully prepared an augite-based glass-ceramic glaze within the CaO–MgO–Al₂O₃–SiO₂ system using economical industrial raw materials. The glaze was prepared via a frit route, involving melting the raw materials, quenching the melt to obtain a frit, ball-milling the frit into a slurry, and finally dip-coating and firing. Systematic investigation revealed that firing at 1150°C produced an optimal microstructure dominated by augite (24.9 wt.%) and cristobalite (20.4 wt.%) crystals, with a refined grain size of ∼1.4 µm. The resulting glaze exhibited properties comparable to conventional ZrSiO₄-based systems, achieving a superior L^* value of 89.21 (+77.6% vs. ceramic body), whiteness of 76.1% (+561.7% vs. ceramic body), and Vickers hardness of 7.10 GPa. These findings confirm that augite-based opaque glazes are a technically viable and more sustainable alternative, offering valuable insights for the development of low-temperature-fired, Zr-free ceramic glazes.

The rapid development of the integrated circuit industry has significantly increased the demand for high-performance substrates. Silicon nitride (Si₃N₄) ceramics, recognized for their excellent thermal and mechanical properties, have become a key focus of research. This study first examines the use of ZrC, characterized by low oxygen content and strong oxygen absorption capacity, as a sintering aid to enhance the thermal conductivity of Si₃N₄. The effects of ZrC-MgO binary additives and ZrC-Sc₂O₃-MgO/MgSiN₂ ternary additives on the density, phase composition, microstructure, thermal conductivity, and mechanical properties of Si₃N₄ were investigated. Results indicate that in the binary system, ZrC reacted with oxygen on the surface of Si₃N₄ during sintering, reducing the secondary phase content, and thinning the intergranular phase. This process resulted in abnormal grain growth and improved thermal conductivity (103.73 W·m⁻¹·K⁻¹) but decreased bending strength (464.33 ± 19.31 MPa). In contrast, the ternary system with Sc₂O₃ effectively inhibited abnormal grain growth, thereby enhancing mechanical properties. Samples with MgSiN₂ exhibited higher thermal conductivity (90.01 W·m⁻¹·K⁻¹) but slightly reduced bending strength (646.00 ± 22.93 MPa) compared to those with MgO. These findings offer strategies for optimizing additive systems in Si₃N₄ ceramics to achieve thinner grain boundaries and a balance between thermal conductivity and mechanical performance.

This study systematically investigates the effects of Y₂O₃/MgO ratio, sintering aid content, and sintering schedule on the microstructure and properties of Si₃N₄ ceramics fabricated via gas-pressure sintering. The results demonstrate that increasing the Y₂O₃/MgO ratio substantially enhances grain growth in Si₃N₄ ceramics, leading to improved thermal conductivity. A balanced Y₂O₃/MgO ratio promotes grain boundary strengthening, achieving optimal flexural strength. Higher MgO content enhances densification in pre-sintering, but excessive volatilization at elevated temperatures introduces defects, degrading performance. Post-sintering heat treatment at 1600°C further improves properties by crystallizing intergranular phases and optimizing liquid phase distribution. Both deficient and excessive sintering aid concentrations result in refined microstructures with weakened grain boundaries, adversely affecting either mechanical strength or thermal diffusion properties. The fabrication of high-performance Si₃N₄ ceramics necessitates both adequate sintering aid content to offset liquid phase volatilization losses and an optimized Y₂O₃/MgO ratio, as these factors critically govern the development of superior thermal and mechanical properties. The SN-5Y2M sample, sintered at 1920°C for 12 h, exhibited excellent comprehensive properties, achieving a thermal conductivity of 129.5 W·m⁻¹·K⁻¹, flexural strength of 635 ± 27 MPa, and fracture toughness of 9.9 ± 0.3 MPa·m^1/2.

TiC-based cermets with various WC contents were fabricated by high-frequency spark plasma sintering (HF-SPS) using the self-synthesized ultrafine TiC powder (0.39 ± 0.14 µm). All specimens achieved relative densities exceeding 99.5%. WC addition significantly inhibited grain growth, and the sample containing 10 wt% WC showed the smallest average grain size of 0.62 ± 0.34 µm. A synergistic enhancement in hardness, toughness, and strength was achieved. Hardness exhibited an initial increase followed by a decrease with increasing WC content, whereas fracture toughness (K_IC) displayed an inverse trend. Transverse rupture strength (TRS) continuously increased with higher WC content. The specimen containing 20 wt% WC demonstrated optimal comprehensive mechanical properties, with hardness, K_IC, and TRS values of 1871 ± 9 HV₃₀, 9.78 ± 0.20 MPa·m^1/2, and 1592 ± 33 MPa, respectively. However, corrosion resistance decreased with increasing WC content. The synergistic enhancement resulted from fine grain strengthening, solid solution strengthening, ceramic-binder interface strengthening, and improved microstructural homogeneity.

The performance of ceramic coatings depends strongly on thermal spray parameters, particularly the number of spray passes. This study investigates the influence of one, three, and five passes on the microstructure, mechanical properties, and chemical stability of ZrO₂–Al₂O₃ coatings on SUS304 stainless steel using atmospheric plasma spraying. Characterization was performed by laser scanning microscopy, scanning electron microscopy, Vickers microhardness, nanoindentation, and energy-dispersive X-ray spectroscopy. Results show that coating quality improves with additional passes. A single pass produced porous coatings with weak splat bonding, poor adhesion, and elemental diffusion from the substrate. Three passes improved densification and mechanical uniformity, although localized defects remained. Five passes yielded the densest lamellar structure with porosity below 2%, hardness above 1050 HV, higher elastic modulus, and stronger chemical barrier properties. Although direct cohesion or adhesion strength measurements were not conducted in this study, these microstructural and mechanical improvements suggest enhanced structural integrity. Overall, the number of spray passes plays a key role in tuning process–structure–property relationships. The five-pass configuration offered the most refined microstructure and performance, providing insights for optimizing plasma spray processes and developing durable coatings for structural, thermal, and corrosion-resistant applications.

In present study, the friction behaviors of high-entropy alloy (HEA)-based diamond composites against ZrO₂ and SiC ceramic ball were studied to provide insights into the grinding mechanism and tribological properties of the HEA/diamond composite as a function of friction ball material. The coefficients of friction (COFs), wear rate, material removal mode, and tribological mechanism of HEA/diamond composites against ZrO₂ and SiC ceramic balls were investigated. The results show that the COF and wear rate against SiC ball are significantly higher than those obtained under the ZrO₂ ball. The main wear mechanism of the HEA/diamond composite against the SiC ceramic ball is adhesion wear, whereas against the ZrO₂ ceramic ball, the wear mechanism is dominated by abrasive wear. On the other hand, the material removal mode is ductile deformation for ZrO₂ and brittle fracture for SiC. Microstructural observation shows that a metallic film is formed between HEA/diamond composite and the ZrO₂ ball, which is transferred to the surface of ZrO₂ and can, thus, reduce the direct contact between ZrO₂ and HEA/diamond composites.

Environmental barrier coatings (EBCs) mitigate the degradation of ceramic matrix composites in harsh environments caused by high-temperature water vapor, molten salts, and corrosive gases, thereby extending component lifespan. This review provides a comprehensive analysis of the degradation mechanisms governing EBC failure, including oxidation, volatilization, calcium‒magnesium‒aluminosilicate attack, steam corrosion, and thermal shock. To establish a foundation, it first outlines EBC materials, processing techniques, and key performance metrics. A detailed examination of phase stability, thermal and chemical compatibility, fracture resistance, and microstructural evolution under service conditions is presented. The influence of deposition methods, coating architecture, and interface design on degradation resistance is highlighted, emphasizing the roles of thermally grown oxides, rare-earth silicates, and multilayer systems. Recent advancements—such as nanostructured coatings, self-healing architectures, and high-entropy ceramics—are also discussed. This review synthesizes current knowledge into a coherent conceptual framework to guide the design and application of next-generation EBCs.

To address the issue of insufficient accuracy in identifying gradual edge features of micro-damage in ceramic bearings, this paper proposes an image enhancement method that integrates fast Fourier transform (FFT) and parameter self-correction guided filtering. The approach involves developing an FFT-based frequency-domain separation model to effectively extract high-frequency detailed textures from the image for enhanced edge characterization. Meanwhile, by incorporating the local variance properties of noise distribution, a self-correcting parameter-guided filtering model is established to strengthen target boundaries and suppress noise interference. Experimental results demonstrate that the processed images achieve a peak signal-to-noise ratio of 44.5971 dB and a signal-to-noise ratio of 89.4046, significantly improving the discernibility and extraction completeness of micro-damage edge features. This study provides an effective image processing solution for the non-destructive testing of micro-damage in ceramic bearings.

Air transport is expected to substantially grow in the next decades, presenting a significant challenge for the aviation industry to reconcile this growth with the need to mitigate climate change by reducing greenhouse gas (GHG) emissions. A viable strategy for diminishing aviation emissions involves reducing aircraft fuel consumption, which can inter alia be achieved by incorporating lightweight ceramic matrix composites (CMC) into aircraft components. However, this is offset by an energy-intensive production of CMC, and there remains limited understanding of the environmental impacts associated with this group of materials. This study aims to assess the potential of carbon/carbon (C/C) wheel brakes to reduce large passenger aircraft emissions. Employing a cradle-to-grave approach, a life cycle assessment based on ISO standards was conducted. The findings indicate that, although the production of a C/C wheel brake incurs a markedly greater carbon footprint than its metallic counterpart, the lightweight and durability aspect of C/C significantly contribute to decreased GHG emissions over the entire service life of an aircraft across all evaluated scenarios. Furthermore, the results emphasize the importance of component durability and improved manufacturing process control in enhancing emission savings, ultimately guiding stakeholders toward informed decisions regarding the use of CMC for sustainable aircraft design.

This paper presents a recent development in the densification-based finite element method (DFEM) of sintering deformation, in which a machine learning model replaces the volumetric component of classical constitutive laws. Accurate constitutive laws are traditionally considered essential for finite element (FE) modeling; however, this study shows that sintering deformation is largely insensitive to parameter variations provided volumetric deformation is captured. Classical models often fail to reproduce densification behavior accurately, motivating the use of artificial neural networks (ANNs). Dilatometer data from multiple thermal profiles were analyzed to determine the activation energy (Q) using the master sintering curve. Additional parameters (Cs1, n, and ζ) were adjusted to fit experimental densification curves. Although FE simulations using these parameter sets produced consistent deformation results, they lacked sufficient accuracy in reproducing the experimental behavior. To address this, ANNs were trained in two steps: first on theoretical data to capture fundamental sintering behavior, and then on experimental data for refinement. Using temperature, integral temperature, and relative density as inputs, the ANN predicted densification rate with high accuracy. The ANN was successfully embedded into ABAQUS via a creep subroutine, providing a robust, scalable, and accurate framework for simulating sintering deformation.