Journal of the Australian Ceramic Society最新文献

This study focuses on how the chemical makeup of the glass' basic components affects the glass' structure and optical characteristics. Four glass samples have been created for this purpose using the chemical formula; 94 mol% Na₂B₄O₇—(6-x) mol% CeO₂ – x mol% Ce(NO₃)₃, where 0 ≤ x ≤ 6. The Ce cations in this formula have two separate chemical sources, CeO₂ and Ce(NO₃)₃, with CeO₂ eventually being replaced by Ce(NO₃)₃. The standard melt-quenching technique was used to prepare the studied glasses. While X-ray direction (XRD), differential scanning calorimetry (DSC), and UV–vis were used for the structural and optical characterizations. XRD patterns revealed the short-range order glass networks for the prepared samples, while DSC thermograms showed that when CeO₂ was replaced with Ce(NO₃)₃, the glass transition temperature (T_g) decreased, causing the glass stability to improve. The optical characterization resulted in the finding that when CeO₂ was replaced with Ce(NO₃)₃, the Urbach's energy increased with a decrease in bandgap energies, which reflects an increase in the glass homogeneity. Finally, the results may imply that Ce(NO₃)₃-based glasses can be proposed for usage in applications for UV blockers, radiation shielding, light attenuation, and n-type semiconductors.

Nowadays, bioglasses have been introduced universally. However, controlling the physical and biological properties of bioglass is complicated. Hence, tailoring their composition and heat-treatment procedures could be beneficial. In the present study, the fluorapatite-containing bioglass-ceramic powders were synthesized via a sol-gel route in two systems, 50SiO₂-39CaO-11P₂O₅ and 64SiO₂-28CaO-8P₂O₅. Furthermore, it is aimed to examine how additives affect the final microstructure by the addition of TiO₂ and ZnO to the chemical formula. Also, another effective parameter that was investigated is the heat-treatment temperature. Based on the XRD and FESEM results, the spherulitic morphology of fluorapatite-containing phases in additive-containing samples proved that the presence of TiO₂ oxide was more influential than ZnO oxide in controlling the crystallization and growth of the desired phases. FTIR results confirmed that increasing the heat-treatment temperature from 700 ℃ to 1100 ℃ caused more intense Si-O and P-O functional groups. There was also no cytotoxicity effect in all samples based on the MTT assay results. Based on the mechanical investigation, the presence of ZnO oxide increased the flexural strength of sintered samples up to 60 MPa.

This study investigates the influence of various anodic oxidation parameters on the photocatalytic activities of the nanostructured titanium dioxide (TiO₂) films. TiO₂ films were prepared by anodic oxidation of titanium substrate using 1 M Na₂SO₄ / 5 wt. % NH₄F electrolyte, and then annealed at 500 °C. Anatase appears in all calcined samples. The anodic oxidation process was performed in two steps at different voltages (5–80 V) and times (15–480 min) to reveal the relationship between the surface morphologies, wettability and photocatalytic properties. The results showed that the voltage and anodization time can play important role in the surface morphology of nanostructured TiO₂ films and thus in various properties. While 40 V showed the most efficient photocatalytic degradation among voltage values, 60 min was the most efficient time for photocatalytic degradation efficiency and lowest contact angle. In addition, a pore area fraction of 39.54%, equal diameter of 96.81 nm, and circularity of 66.7% were obtained from image analysis of the 60-min anodized sample. While increasing the voltage and time benefited up to a point in terms of photocatalytic efficiency, changes in morphology had a negative effect after a point. At low voltage and time values, small pore diameters result in low photocatalytic properties. This titania can be readily utilize to meet application expectations in areas such as gas sensors, photocatalysis and photovoltaic cells.

BaBiLaNbVO₉ is a lead-free compound and has been synthesized by solid-state technique. The formation of the compound was confirmed by X-ray diffraction and is found to be crystallized in the monoclinic (space group P 2₁) crystal system (a = 13.7464± 0.0015 Å, b = 4.0156± 0.0012 Å, c = 12.4946 ± 0.0018 Å, β = 93.48 ± 0.01^o). The crystallite size was found to be 52.91 nm. SEM and EDX studies analyzed the morphology, composition, and elemental distribution in the specimen. The average grain size is about 1.0651 μm. Several properties, such as frequency and temperature response resistivity, conductivity, and dielectric behaviours of the compound, have been analyzed. The overlapping large polaron tunnelling (OLPT) and correlated barrier hopping (CBH) models are appropriate for electrical conduction in the compound. The energy band gap (E_g) of the material was 2.40 eV, suitable for optoelectronic devices. Ferroelectric behaviour may be deduced from symmetric and well-shaped P-E hysteresis loops. The impedance study satisfies the negative temperature coefficient of resistance (NTCR) behaviour, which is suitable for thermistor devices and its correlated application.

Alkali-activated materials (AAMs), which are prepared by using various solid wastes as precursors and reacting with alkaline solutions, are gradually applied in the construction industry. However, not all solid waste precursors can exhibit good performance in the preparation of AAMs. To realize the effective utilization of phosphorus slag (PS) solid waste, alkali-activated PS-GBFS-FA (AAPGF) was prepared by using PS and GBFS/FA. Using different contents of GBFS/FA to replace PS, the workability performance, mechanical properties and hydration products of AAPGF were investigated. The incorporation of GBFS/FA improves the fluidity of AAPGF, but leads to slurry flash setting. When containing 30% GBFS/FA, the 28 days compressive strength of AAPGF can reach the highest 72.65 MPa. GBFS/FA increased the number of C-(A)-S-H gels, accompanied by the formation of hydrotalcite gels. In addition, GBFS/FA also transforms AAPGF hydration products from C-S-H gel to C-(N)-A-S-H and N-A-S-H gel with high degree of polymerization, and SiO₄ tetrahedron is Q² unit. GBFS/FA will significantly reduce unhydrated particles, but it will lead to uneven distribution of hydration products and produce large pores. The results of this study can provide reference value for the effective use of PS.

In this study, thermal analysis, composition phase, microstructure and physical and mechanical properties of Al₂O₃-based composites with titanium diboride and carbide reinforcements fabricated by in-situ spark plasma sintering method in Al-FeTiO₃-B₂O₃-C alumino-thermic system have been investigated. This research explores the potential of utilizing Kahnuj (Iran-Kerman) ilmenite concentrate as a replacement for TiO₂. The results of the thermal analysis demonstrate that aluminothermic reactions significantly intensify after the melting of aluminum and different compounds of iron aluminides (FeAl, Fe₂Al₅, and Fe₃Al) and titanium diboride (TiB₂) and carbide (TiC) are formed. Among the different systems of raw materials (Al-FeTiO3-C, Al-FeTiO₃-B₂O₃, and Al + FeTiO₃ + C + B₂O₃) only for system Al + FeTiO₃ + B₂O₃, the intermetallic compounds of Fe₃Al and Fe₄Al₁₃ are stable. For heat treatment with higher heating rates, the boron oxide participates more effectively in the aluminothermic reaction and the composition of titanium diboride is more noticeably formed. In the condition of 45 MPa in mechanical pressure, argon gas atmosphere with 3 bar pressure, heating rate of 100 °C/min, temperature of 1400 °C with dwelling time of 4 min (Optimum condition) for in-situ SPS processing of Al-FeTiO₃-C system, the composite samples with the highest homogeneity in microstructure, density (4.10 g/cm³), hardness (281HV), bending strength (271.5 MPa) and highest wear resistance (Friction coefficient of 0.3 and 0.003 g of weight loss with 500 m of sliding distance) with optimal phase composition (Fe, Al₂O₃, TiC,…) was obtained.

The aim of this study was to develop and characterize coatings of bioglass nanoparticles (BGNs) on biopolymer (poly [glycolide-co-L-lactide], (PGLA)) surgical sutures, and to investigate the effects of these coatings on the performance of the sutures as they slid through a skin substitute. Melt-derived BGNs were used to coat resorbable PGLA biopolymers, providing them with bioactivity, biocompatibility, and improved physical and mechanical properties. The structural, thermal, and physical properties of the coated and uncoated biopolymers were analyzed using Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FE-SEM) and Energy-Dispersive X-ray Spectroscopy (EDXS). The dissolution profiles and bioactivity of the BGNs-coated PGLA biopolymers were assessed through Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Tensile strength tests were conducted on the biopolymers before and after immersion in simulated body fluid to evaluate the impact of the BGNs coating on the degradation of PGLA biopolymers. Incorporating BGNs into PGLA resulted in improved tensile strength properties. The study also found that increasing the BGNs ions content facilitated the formation of a hydroxycarbonate apatite (HCA) layer in Dulbecco’s Modified Eagle Medium and medium with L-glutamine and sodium bicarbonate solutions. In vitro bioactivity tests demonstrated that the coated suture biopolymers exhibited enhanced attachment, migration, and proliferation of fibroblasts, indicating favorable biocompatibility of the biomaterial for clinical applications.

SiO_2f/SiO₂ composites were prepared by compression molding and sintering using short-cut quartz fibers as reinforcement. The effects of fiber volume fraction (15%∼35%) on bulk density, apparent porosity, and mechanical and thermal properties of the composites were investigated. The results indicated that the samples with 25% fiber volume fraction had the best comprehensive performance, with an apparent porosity and compressive strength of 36% and 46.3 MPa, respectively. The flexural strength of the samples was 13.9 MPa, which represented a 90% increase compared to the samples without fibers. It was attributed to the occurrence of fiber debonding and fiber pull-out in the porous matrix. Meanwhile, the residual strength ratio of the samples after 20 thermal shocks was 74.8%. In addition, the average coefficient of thermal expansion was 0.95 × 10^− 6/℃ at 300 ℃∼700 ℃ and the thermal conductivity was 0.388 W·m^− 1·K^− 1 at 800 °C. This approach can satisfy the requirements of low cost, fast preparation of SiO_2f/SiO₂ composites, which offers the prospect of its application in the integration of load-bearing and thermal insulation.

In this study, a series of aluminum borate ceramics (ABCs) with needle-like whiskers were obtained using a low-cost, solid-state, pressureless sintering ceramic route, without any additives during the preparation process. The effects of different alumina/boric acid molar ratios and sintering temperatures on the phase composition, microstructure, mechanical properties, specific surface area, pore size distribution, and sub-cadmium neutron shielding properties of ABCs were studied using orthogonal experiments. It was observed that pure phase aluminum borate (Al₁₈B₄O₃₃) ceramics could be obtained at 1100 ℃, forming a mass of needle-like whiskers. The whiskers’ aspect ratio, fracture work, specific surface area, and pore size distribution of ABCs are maximized when ABCs are sintered at 1100 ℃ with 9:6 alumina/boric acid molar ratio. In this condition, ABCs (0.5 cm) can shield 70% of sub-cadmium neutrons (E<0.4 eV). These findings demonstrate the great potential of aluminum borate ceramics for neutron shielding applications.