International Journal of Ceramic Engineering & Science最新文献

Amid growing environmental concerns and the search for sustainable building materials, this study investigated the mechanical and microstructural behavior of clay-based mortars reinforced with coconut fibers. Mixtures were produced in which natural sand was replaced by sand and clay residues, with fiber additions of 2.5% and 5% by weight of cement. The mortars were evaluated in fresh and hardened states, compressive and flexural strengths, and through scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD) analyses. The clay residue produced compressive strength values comparable to the reference mixture. The incorporation of 5% coconut fibers resulted in a statistically significant increase in flexural strength compared to the non-reinforced mortar, despite the formation of shrinkage-induced microcracks. The analysis confirmed the presence of quartz, kaolinite, orthoclase, and calcium aluminum silicate. The results highlight the potential for applying waste and natural fibers in eco-efficient mortars, emphasizing the importance of curing and moisture control.

Viscosity is a fundamental physical property that governs the flow and processing behavior of glass-forming liquids. During glass manufacturing processes, it is thus important to know how rheological properties are influenced by variables such as temperature, chemical composition, and the presence of any inclusions within the melt. There is extensive literature describing theoretical models for calculating the viscosity of oxide glass-forming systems; resources dedicated to experimental methodologies for measuring oxide glass viscosity are comparatively scarce. This review therefore focuses on direct viscometry techniques as well as indirect approaches for measuring viscosity including differential scanning calorimetry (DSC) and dilatometry combined with the Mauro–Yue–Ellison–Gupta–Allan (MYEGA) model. In addition, we highlight emerging machine-learning approaches, which offer complementary insights into glass viscosity, particularly in complex multicomponent systems. Such machine learning-based methods require large and high-quality datasets for training and validation, underscoring the vital importance of experimental measurements in establishing reliable viscosity values. Overall, the primary goal of this review is to fill a gap in the literature regarding experimental methodologies for viscosity measurement of oxide glasses, explaining their underlying principles, highlighting the challenges faced by researchers, and emphasizing the continued necessity of experimental viscosity measurements alongside theoretical and computational approaches.

From a materials-computation perspective, this study integrates the electron-excitation model of double Schottky-barriers with a Voronoi network to characterize the microscopic electrical and structural properties of ZnO varistors. The quantitative influences of two pivotal barrier parameters—the grain donor density N_d and the grain-boundary interface-state density N_i—on macroscopic electrical performance metrics such as voltage gradient, leakage current, and current-withstand capability are systematically investigated. The reliability of the model is corroborated by accelerated aging tests on samples featuring a graded Y₂O₃ doping profile, which also elucidate the effects of yttrium incorporation on varistor performance and aging resistance. The findings furnish a theoretical foundation for the design and fabrication of high-performance ZnO varistors and are of significant value for the development of surge arresters.

Planetary ball milling of β-tricalcium phosphate (β-TCP) powders in acetone using 1 mm zirconia beads as milling media has been shown to produce largely amorphous, anhydrous calcium phosphate powders. This method enhances the release of Ca²⁺ and phosphate ions from the resulting particles. In this study, silver ions were successfully and uniformly incorporated into the calcium phosphate matrix by adding just 1 wt% Ag₃PO₄ during the mechanochemical process, allowing for the straightforward fabrication of particles with well-dispersed Ag⁺ ions. When 5 wt% Ag₃PO₄ was used, both dispersed Ag⁺ ions and metallic silver nanoparticles were detected. Upon immersion in HEPES buffer solution (pH 7.40), the concentrations of Ag⁺, Ca²⁺, and phosphate ions increased significantly within 24 h. Powder x-ray diffraction revealed time-dependent changes during immersion, attributed to hydroxyapatite formation. Antibacterial testing showed that particles doped with 1 wt% Ag₃PO₄ exhibited strong antibacterial activity against Escherichia coli and Staphylococcus aureus. This mechanochemical route offers a simple and effective method for uniformly incorporating trace levels of silver ions into anhydrous amorphous calcium phosphate particles.

Plastic-forming methods of ceramic pastes, such as extrusion, have been significant in the ceramics industry for many years. Despite its significance, the plasticity of ceramic pastes is poorly understood. It is essential to understand the fundamentals of ceramic paste plasticity to develop a forming technology with superior performance. The ceramic pastes’ plasticity can be characterized by the co-existence of apparently opposing properties, that is, “flowability” and “rigidity.” It has been claimed that the apparently opposing properties can be achieved by controlling the interparticle interaction that is attractive at long range and repulsive at short range. The present article aims to verify the model based on experimental results from interaction force measurements. The interaction forces are gathered by the atomic force microscope (AFM) colloid probe technique. On the basis of the discussion, it is concluded that the above microscopic model is available to interpret ceramic pastes’ macroscopic behaviors.

Nuclear waste storage applications require a new type of cementitious material having lower pH than Portland cement and compatibility with embedded steel. Since phosphates can be used as both pH buffers and corrosion inhibitors in carbon steel, a series of phosphate-containing alkali-activated materials were prepared from MgO-Al₂O₃-SiO₂-P₂O₅ precursor materials with various MgO, Al₂O₃, SiO₂, and P₂O₅ concentrations. These samples were activated with sodium hydroxide and cured for 28 days at 35°C. The impact of precursor phosphate content on pore solution composition and pH was examined using cold-water extraction (CWE) and Gibbs energy minimization (GEM) modeling. For samples activated with the same amount of sodium, higher phosphate content in the precursor material leads to lower pH in the pore solution. When the pore solution is saturated with sodium phosphate and the soluble Na/P ratio is between 2 and 3, the pH decreases from 15.1 ± 0.1 in the absence of phosphates to 11.0 ± 0.1 with phosphates. The resulting pore solution and a precipitated mixture of di- and tri-sodium phosphate have a buffering effect on the pore solution's pH and Na⁺, keeping the pH and Na⁺ concentration near 11.0 and 1.0 mol/kg, respectively. This pH is within the range desired for certain nuclear waste storage applications.

TiB₂–TiC composite ceramics were synthesized by boro/carbothermal reduction of oxides and densified by spark plasma sintering. Thermodynamic processes within the reaction system were discussed, and phase diagrams were constructed to guide formulation design. In addition, the phase constituents, impurity content, micromorphology of the powders and densification, mechanical properties, and oxidation resistance of the composite ceramics were studied. The results indicate that reasonable adjustment of carbon content can effectively regulate the phase content in the composite ceramics, allowing for adjustable TiB₂ content within the range of 35–75 wt%. Additionally, it suppresses excessive grain growth of boride, maintaining the grain size of both phases at approximately 200 nm and reducing the residual C and O impurities. When the ratio of TiB₂:TiC in the powder is 64.1:35.9 wt%, the grain sizes of the two phases are most similar, resulting in the highest density of sintered TiB₂–TiC composite ceramics, reaching 99.78%. The corresponding Vickers hardness can reach 24.07 ± 0.53 GPa.

When the surge arrester is subjected to the working voltage for an extended period, it undergoes alternating current (AC) aging, which degrades the arrester's parameters and affects the safety of the power grid. Ni₂O₃ is an important additive in the ZnO varistor formulation, and its doping ratio significantly influences the performance of the ZnO varistor. In this paper, varistor samples were fabricated by varying the doping ratio of Ni₂O₃ in the ZnO varistor, and accelerated AC aging experiments were conducted. The key electrical parameters and barrier parameters of the samples before and after aging were measured. The data show that as the doping ratio of Ni₂O₃ in the formulation increases, the volt-ampere characteristic curve of the arrester resistor shifts toward higher electric field strength before aging and toward higher current after aging. The E_1mA after aging increased from 303.58 V/mm to 442.53 V/mm. The barrier height of the samples before and after aging first increased, then decreased, and then increased again. The maximum difference was observed when the doping ratio reached 1.50 mol%. After the AC aging test, the Ni content in all samples decreased, with the smallest change rate observed in ZYN10 and the largest in ZYN15, at approximately −12%.

The urgent need to mitigate climate change has driven the exploration of innovative materials and processes to achieve net-zero carbon emissions. This work investigates the potential of ceramic matrix composites (CMCs) as alternatives to traditional metals in high-temperature industrial applications, within the European Union project CEM-WAVE. Various joining materials, including glass-ceramics, metallic brazes, and pre-ceramic polymers, are evaluated for their effectiveness in creating robust CMC joints. The study demonstrates the viability of CMCs in steelmaking and other energy-intensive sectors, highlighting their resistance to extreme conditions and potential to replace metallic alloys. The findings underscore the need for continued research to optimize manufacturing processes and reduce costs, paving the way for broader adoption of CMCs in achieving sustainable industrial practices.

In this research, the innovative ceramic production process begins with the drying and grinding of raw materials to a fine powder, which is then sieved and dampened before being shaped into ceramic forms using a stainless-steel mold. The material is pressed at 400 bars for 15 s to form a 10-mm-thick ceramic. The ceramic pieces are then air-dried and subjected to further drying in an oven before undergoing a heat treatment process. The heating is carefully controlled, increasing the temperature at a rate of 5°C per minute until a sintering temperature is reached, allowing the material to undergo the necessary thermal effects to form a durable ceramic structure. The innovative ceramics exhibit excellent performance in several key areas. In anti-acid tests, they demonstrate a 92% resistance to acid attack, significantly outperforming the control sample at 68%. This improved chemical durability is primarily attributed to the stable silicate alumina network and optimized body glaze composition, which minimizes leachability and enhances structural stability. Oxides such as CaO and MgO likely contribute indirectly by promoting phase stability and densification rather than direct acid neutralization. The abrasion resistance test reveals that the innovative ceramics maintain over 98% of their mass after 2100 rubbing cycles, owing to the high contents of SiO₂, Al₂O₃, and MgO that enhance mechanical strength and wear resistance. Additionally, the flexural strength increased to 42.0 ± 0.3 MPa, compared with 38.4 ± 0.2 MPa for the control sample, due to the reinforcing effects of oxides such as CaO and MgO, which improve overall microstructural cohesion. These combined properties result in highly durable and chemically resistant ceramics suitable for demanding applications.