Journal of the Australian Ceramic Society最新文献

The aim of this study was to investigate the two-and three-body friction and wear characteristics of three different dental composites (flowable bulkfill, single shade, and conventional composites) in artificial saliva and poppy seed slurry. Tribological tests were performed using a reciprocating ball-on-flat-type tribometer according to ASTM-G133. The tested composites exhibited clear differences in terms of their wear and friction behaviors depending on their hardness, microstructure, and test media. The results showed that conventional and single-shade composites may have more positive results in posterior teeth because of their more durable wear characteristics, especially in two-body wear, whereas an additional capping layer using a wear-resistant dental composite with improved tribological behavior is necessary to finish the restorations when using flowable bulkfill composite.

To combat bacterial resistance, there are not enough novel antibacterial substances currently being developed at this time. The search for novel antibiotics and their introduction into the pharmaceutical industry are very difficult tasks. Consequently, it is crucial to develop novel approaches to combat bacterial resistance and stop bacteria from becoming resistant. Although ferrites and zinc oxide are widely used in mechanical, chemical, and electrical engineering, little is known about their potential as biomaterials. The goal of this work was to synthesize a novel antibacterial composite containing ZnFe₂O₄ and ZnO doped by Ho. A vibration sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD) were used to characterize the produced antibacterial. The crystallite size of prepared sample is calculated to be 16.7 nm, as shown by X-ray diffraction (XRD). The images from the field emission scanning electron microscope (FESEM) depict the samples’ morphology. The platelets in the sample are spherically formed and have a hexagonal shape. The micrograph is not consistent. VSM shows that the studied nanoparticles exhibit paramagnetic behavior. The effective magnetic moments were found to have been 0.14µ_B. The optical band gap (E_g) was measured to be 2.3 eV. Intermolecular interaction raises the refractive index of the nanocomposite, while interfacial polarizations and widening band gaps at the conductor-insulator interface are responsible for its high optical conductivity. When the nanocomposite was tested against both gram negative bacteria like K. pneumoniae and E. coli, Gram positive bacteria like S. aureus and B. subtilis as well as the fungal species C. albicans. Overall, ZnFe₂O₄/Zn_0.97Ho_0.03O nanocomposite shows that it has a strong potential for antibacterial applications in medicine.

Clay bricks are widely used in construction due to their sustainability and cost-effectiveness. However, challenges such as high density and thermal conductivity hinder their broader application in energy-efficient buildings. This study investigates the effects of an expansion additive and varying firing temperatures (1000–1150 °C) on the physicomechanical properties of lightweight clay bricks. Six sample groups were prepared, incorporating expansion additive ratios from 0 to 4%. Key properties, including unit volume weight, water absorption, porosity, compressive strength, and thermal conductivity, were evaluated. Results identified the optimal conditions as 3.5% expansion additive and a firing temperature of 1150 °C, yielding a unit weight of 712 kg/m³, thermal conductivity of 0.1795 W/mK, and compressive strength of 7.05 MPa. These findings demonstrate the potential of chemically modified lightweight bricks for sustainable, energy-efficient construction.

This study explores the impact of calcination temperature on the characteristics of YBa₂Cu₃O_7−δ (Y-123) ceramic superconductors, synthesized using a novel modified thermal decomposition (MTD) method. It aims to optimize the relationship between calcination conditions and superconductor performance, which is critical for advancing the utility of high-temperature superconductors (HTS). The calcination process involved two distinct temperatures: 850 °C (Group A) and 910 °C (Group B), each sustained for a duration of 24 h. Following calcination, the samples underwent sintering at varying temperatures: 920 °C, 950 °C, and 980 °C. This process facilitates the examination of how thermal treatment affects the structure-property relationship to find the best conditions for enhanced superconductor performance. The characterization techniques employed encompassed thermogravimetric analysis (TGA/DTG), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and four-point probe measurements (4PP). Thermal stability was examined using TGA-DTA analysis. The XRD analysis revealed the existence of the orthorhombic structure featuring the Y-123 phase in both Group A and Group B with a minor secondary phase, Y₂BaCuO₅ (Y211). The samples calcined at 910 °C exhibited the highest critical temperatures, such as T_c−onset (93.72 K) and T_c−zero (90.27 K), with the lowest superconducting transition width, ΔT_c (3.45 K), at a sintering temperature of 980 °C. Furthermore, an increase in both homogeneity and density was noted with the gradual rise in sintering temperature. FESEM analysis revealed that the sample in Group B exhibited the most densely compacted grain structure and the highest T_c−zero, implying that enhanced interconnectivity among the grains leads to an elevation in T_c−zero. This study underscores the significance of precise thermal processing and introduces a viable method for synthesizing high-T_c superconductors.

The micro crystallization of glass fibers would be expected to enhance their mechanical and chemical properties, thereby facilitating their further utilization. In this paper, glass-ceramic fibers were prepared by crystallizing Li₂O-Al₂O₃-SiO₂ (LAS) glass fibers. The effect of crystallization time on lithium-aluminum-silica glass-ceramic fibers was investigated. The results demonstrate that pristine glass fibers are highly susceptible to crystallizing in the form of surface crystallization. LAS glass-ceramic fibers with a diameter of 20 μm were prepared with tensile strengths up to 270 MPa and a significant improvement in alkali resistance. The precipitated hydrogen aluminum silicate and lithium silicate grains from glass fibers were dispersed in the glass network, which increased the density of the glass network. This, in turn, improved the chemical properties of the fibers.

Fast hot-press sintering was employed to fabricate SiC-based composite ceramics reinforced by a single high-entropy boride (HEB) phase, specifically Ti₀.₂Zr₀.₂Hf₀.₂Nb₀.₂Ta₀.₂)B₂. The synergistic grain refinement between the SiC and HEB phases resulted in fine microstructures while preserving high hardness in the SiC-HEB composites. As the solid-state sintering temperature increases, the distribution of metal cations in the HEBs becomes more uniform, the relative density rises significantly, and the material’s fracture toughness enhances. The composites achieved a maximum hardness of 23.75 GPa at 1800 °C and peak fracture toughness of 5.1 MPa·m^1/2 at 2000 °C. Compared to previously reported SiC-HEB systems, these ceramics exhibit a superior balance of mechanical properties, making them promising candidates for high-temperature structural applications.

The article presents research results on radio-transparent strontium-anorthite ceramics, in which some components were introduced using eutectic glass of the SrO–Al₂O₃–SiO₂ pseudoternary system. During the firing process, the principle of reactive formation of the ceramic structure is realized. The resulting dense material was obtained at relatively low temperatures 1200 °C. The only crystalline phase of the developed ceramics is the monoclinic form of strontium anorthite, which forms a homogeneous structural matrix of the material. The developed strontium-anorthite ceramics are characterized by a low thermal linear expansion coefficient of (39.2–39.7)×10^− 7°C^-1, which ensures their high thermal stability (750 °C). The synthesized ceramics meet the requirements for high-frequency radio-transparent materials, including structural ones, with a relative dielectric permittivity of (5.1–5.3) and dielectric loss of 0.001 at a frequency of 10¹⁰ Hz.

Graphical Abstract

Hybrid nanofluids typically exhibit improved thermal conductivity and heat transfer characteristics compared to single-component nanofluids. This is due to the synergistic effects of combining different nanoparticles. Because of these properties, they were used in key applications such as heat exchangers and cooling systems. The primary goal of this research is to evaluate the heat transfer efficiency and performance of a heat pipe using different hybrid nanofluids such as Water + Al₂O₃, Water + Al₂O₃ + CuO, and Water + Al₂O₃ + ZnO under varying heat inputs of 20 W, 40 W, 60 W, 80 W, and 100 W respectively. The study revealed that the hybrid nanofluids achieved higher heat transfer rates, stability, and improved thermal conductivity when supplied at a heat input of 100 W to the heat pipe. The two-hybrid nanofluids used in the study, Water + Al₂O₃ + CuO and Water + Al₂O₃ + ZnO exhibited approximately 24% lower thermal resistance, higher heat transfer coefficient of 32%, and enhanced thermal conductivity when compared with the Water + Al₂O₃ nanofluid.

In this study, an attempt was made to develop a high strength thermal resistant friction material using ceramic fiber as the main fiber and varying the wollastonite content. In addition to the ceramic fiber, 19 various ingredients were considered as fibers, frictional additives and fillers for improving the performance of the composite. The main challenge is to develop a friction material capable of withstanding dynamic loads and severe temperatures encountered during braking. Three friction materials (CERA-I, CERA-II, and CERA-III) were fabricated using a hot press method. After fabrication, the samples were evaluated for physical and mechanical properties. The actual performance was predicted using a friction test rig equipment. The tests were carried at pressures of 30 MPa and 15 MPa under a speed of 600 rpm. The materials were characterized using Scanning electron microscope (SEM), EDXA, porosity and thermo-gravimetric analysis (TGA) for determination of distribution of ingredients and chemicals present in the composite. The results revealed that, inclusion of ceramic fiber with other ingredients possess superior properties in terms of mechanical, physical and wear properties. Out of these three samples, CERA-III friction material exhibited better performance compared to the remaining samples.

The tungsten-based oxides have emerged as a potential electrocatalyst for (HER) hydrogen evolution reaction as well as (OER) oxygen evolution reaction. Notably, catalytic potential of tungsten oxides in the OER has yet to be studied. In present work, we offer a new nanoarray-structured electrode composed of BiLaWO₆/PPY. In alkaline conditions, this unique electrode catalyzes both the OER and HER with excellent stability and efficiency. In comparison to the reversible hydrogen electrode, BiLaWO₆/PPY nanoarray structure considerably increase hydrogen gas release from the electrode, generating a remarkable current density of 10 mA cm^− 2 at an initial potential of 245 mV with a 78 mV overpotential for HER. Furthermore, this BiLaWO₆/PPY nanocomposite displays Tafel slope of 64 mVdec^− 1. On other hand, the BiLaWO₆/PPY nanoarray shows good OER activity having 1.42 onset potential with overpotential of 244 mV. In order to validate the reaction process using current density of 10 mA cm^− 2, additionally, resulting material displays a Tafel slope (34 mVdec^− 1)for OER. This demonstrates that it is a promising non-noble metal catalyst for green water splitting using 1 M KOH. Consequently, the implementation of BiLaWO₆/PPY nanoarray in the context of this research signifies an innovative strategy for advancing OER electrocatalysts and other devices utilized in energy conversion and storage system.