Journal of the Australian Ceramic Society最新文献

This study aims to understand the influence of pore size on the compositional, morphological, and functional group characteristics of dicalcium phosphate dihydrate (DCPD)-coated porous β-tricalcium phosphate (β-TCP) granules. This study produced 300–600 μm granular sizes of porous β-TCP granules with various pore diameters. This was achieved by combining dry powders of DCPD and calcium carbonate (CaCO₃) [Ca/P ratio: 1.5] with varied quantities of 10%, 20%, 30%, and 40% of sodium chloride (NaCl) powders to obtain mixtures composed of weight percentages (wt%) ratios of 90:10, 80:20, 70:30, and 60:40, respectively. Post-sintering, the porous β-TCP granules fabricated were soaked in an acidic calcium phosphate solution for 30 min to coat the surfaces with DCPD crystals formation via a dissolution-precipitation reaction. Subsequently, the specimens were examined with scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR). The morphological observations demonstrated that increasing NaCl powder up to 40% with a mixture of CaCO₃ and DCPD enhanced the β-TCP granules' pore size. Furthermore, The formation of DCPD on and inside the porous β-TCP granules has been accelerated due to the presence of large pores. Conversely, dissolution-precipitation reactions were incomplete on granules with 2.8, 4.9, and 6.91 μm pore sizes. The major XRD peaks of the DCPD and β-TCP phases with 2.8, 4.9, and 6.91 μm pores were also slightly shifted to the right, while granules with 7.53 μm pores demonstrated DCPD and β-TCP peaks aligned with pure β-TCP and DCPD phases. This study's findings are expected to offer insight into the role of pore size in influencing the dissolution-precipitation process that affects the morphological, compositional, and functional group characteristics of DCPD-coated β-TCP granules.

In this study, the wetting and corrosion behavior of slags containing vanadium (V) and titanium (Ti) on the oxidized surface of MgO–C refractory (MO), were investigated. The microstructures and phase compositions were analysed at the interface between the slag and MO substrates, alongside an examination of the corrosion mechanism. The findings unveiled that adding V₂O₃ and TiO₂, whether individually or in tandem, reduced the slag’s melting point and the contact angle between the slag and MO substrate. The molten slags mainly penetrated the MO substrates through pores, cracks, and grain boundaries, forming silicate, and vanadate phases at the slag–MO interface. In particular, the V–containing slag demonstrated stronger susceptibility to corrode the MO substrate due to the capacity of V to form low–melting point phases with MgO. This led to deeper penetration and a larger corroded area within the substrate. These findings offer valuable insights for the design and optimization of slags containing V and Ti and MgO–C refractory materials in metallurgical processes.

Al₂O₃ ceramic honeycomb sandwich bars with a hexagonal core were manufactured through SLA 3D-printing to analyze the impact of hole placement, designed for the removal of uncured slurry, on the bending strength of the samples. Several holes were placed specifically on the samples in the design in two different ways. In the initial design, the holes were placed on the honeycomb sandwich structure’s upper and lower face-sheets. In the second design, the holes were positioned in the direction of the sample thickness, in the lateral walls. The moment of inertia values for the honeycomb structures were calculated with the help of experimental elastic modulus results, and true bending strength was determined according to these results. Nominal strength values were found using the common three-point bending formula. The true bending strength value of Al₂O₃ with lateral holes was 73% higher than Al₂O₃ with holes on face-sheets, while the nominal bending strength was 79% higher. Al₂O₃ samples with holes on face-sheets exhibited a significantly higher failure index compared with both the bulk samples and the Al₂O₃ samples with lateral holes. The holes on the face-sheets reduced the cross-sectional area of the tensile surface and contributed to an increase in stresses due to the stress concentration effect. The Al₂O₃ samples with lateral holes provided a great advantage of specific strength, reaching an average value of 65% above the specific strength of the bulk samples.

This study involves the investigation of the effect of the replacement of B₂O₃ with La₂O₃ on the properties of the multi-component lead Borovanadate glass. Five samples were prepared using the fast-quenching method according to the chemical formula (43-x) mole % B₂O₃ - x mole % La₂O₃- 10 mol % V₂O₅-12.5 mol % CaO-12.5 mol % Li₂O -22 mol %PbO, where x = 0, 1, 2, 3, and 5 mol %. The amorphous character of the synthesized samples was confirmed via Fourier transform infrared and X-ray diffraction. XRD patterns suggest a lack of long-range organized crystalline structure, but FTIR reveals various structural unit blocks. On the other side, the increment of La₂O₃ content caused a proportional increase in the glasses’ bulk density and molar volume. UV analysis revealed that the sample with 5 mol % La₂O₃ had superior absorption properties compared to the other samples. All the samples were found to be effective in transmitting light within the energy range of 3.43–4.07 eV, with the La₂O₃-free sample demonstrating the highest level of light transmission among all the samples. The radiation shielding characteristics of the synthesized glasses were analyzed. The theoretical predictions for the mass attenuation coefficients using WinXCom agreed well with the measured values, providing validation for both the software and the experimental techniques used. This investigation found that La₂O₃ concentration influenced the linear attenuation coefficient (LAC) at a defined energy level, with higher La₂O₃ resulting in higher LAC values. The study also showed that lower energy levels had better linear attenuation compared to higher ones.

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.

SiAlON ceramics is a unique material used in various applications. Producing porous SiAlON material from available industrial waste by combustion is of great interest. In this work, a porous SiAlON composite was synthesized by the combustion of a mixture of aluminum ferrosilicon powder and aluminosilicate hollow microspheres in nitrogen. Aluminosilicate hollow microspheres were used as a pore-forming agent. The addition of aluminosilicate hollow microspheres to aluminum ferrosilicon powder increased the total porosity from 34.1 to 90.3%, the open porosity from 16.4 to 88.2%, and the maximum pore size from 53 to 413 μm in the final product. The porosity of the synthesized samples was predominantly open.

How to properly handle the high-level radionuclides cesium(Cs) and strontium(Sr) generated during the nuclear fuel cycle has become a challenging issue. Geopolymer, a novel aluminosilicate inorganic gel material, can be in-situ converted into zeolite and ceramics, exhibiting excellent immobilization capability for radioactive nuclides. This work provides a comprehensive review of the research on the conversion and synthesis methods of geopolymer into zeolite and ceramics, and conducts a detailed analysis of the performance and mechanisms of geopolymers, geopolymer-zeolite composites, and geopolymer ceramics in the immobilization of Cs and Sr. Through a thorough analysis and summary of existing literature, this study presents the optimal conditions for the conversion of geopolymers into zeolite and proposes improved methods for geopolymer ceramic immobilization of Cs. Furthermore, a comparison and analysis are conducted of the applicability, as well as the advantages and disadvantages of these three solidification matrices in immobilizing Cs and Sr. Finally, the challenges and prospects faced by geopolymer and its derivative materials in the immobilization of high-level radionuclides Cs and Sr are discussed.

In this work, to establish the oxidation resistance for graphite in the air atmosphere with temperatures ranging from 700 to 1000 °C, an innovative multi-component, dual-layer coating was developed. The coating consists of two layers with a total thickness of around 250 μm. The first layer was consisted of B₂O₃ with SiO₂ and ZnO, while the second layer included SiC with silicon as an additive. Through scanning electron microscopy (SEM) images and elemental maps, alongside heat treatment experiments at 1000 °C, which resulted in only a 6% weight loss, it was evident that the coating was effectively applied and performed exceptionally well. Moreover, cyclic heat treatment experiments confirmed the coating’s durability and thermal stress resistance, with minimal weight reduction results. Applying these coatings is uncomplicated, and the materials are readily available, ensuring cost-effectiveness.

Graphite material is a kind of conductive material with excellent thermal shock resistance, is an important strategic mineral resources, widely used in iron and steel smelting, aviation, aerospace and other fields. However, the graphite electrode is easy to be oxidized in the air, resulting in a large amount of graphite electrode loss. In this paper, a new impregnation material is used to prepare graphite electrode oxidation resistance coating, by changing the ratio of raw materials, impregnation times, sintering process and other process parameters to prepare samples, and then oxidation resistance experiment to characterize its antioxidant capacity. The optimum technological parameters of graphite electrode coating obtained in this paper are: The content of antioxidant is Si 4.6%, SiC 5.8%, TiO₂ 6.9%, Al₂O₃ 5.4%, H₃BO₃ 3.7%, carboxymethyl cellulose 2.6%, deionized water 70%, hot impregnation twice, after sintering in nitrogen atmosphere at 400 ℃ for 30 min, In the range of 800 ℃~1200 ℃, the weight loss of the graphite samples with anti-oxidation coating is reduced by 7.3%~11.3%. The coating can protect the anti-oxidation of the graphite matrix well.

Hydrogen (H₂), a renewable energy source with a high energy density and a reputation for being environmentally benign, is being lauded for its potential in various future applications. In the present context, the catalytic methanolysis of sodium borohydride (NaBH₄) is of considerable importance due to its provision of a pathway for the efficient production of hydrogen gas (H₂). The main aim of this research attempt was to assess the viability of utilizing refuse defatted sumac seeds as an unusual precursor in microwave-assisted K₂CO₃ activation to produce a biocatalyst.

The primary objective that motivated the synthesis of the biocatalyst was to facilitate the generation of hydrogen via the catalytic methanolysis of NaBH₄. With the aim of developing a biocatalyst characterized by enhanced catalytic performance, we conducted an exhaustive investigation of a wide range of experimental parameters. The activation agent-to-sample ratio (IR), impregnation time, microwave power, and irradiation time were among these parameters.

Significantly enhanced in catalytic activity, the biocatalyst produced under particular conditions achieved a peak hydrogen production efficiency of 10,941 mL min^− 1 g.cat^− 1. In particular, it was determined that the ideal conditions were as follows: 0.5 IR, 24 h of impregnation, 500 W of microwave power, and 10 min of irradiation. This novel strategy not only demonstrates the impressive potential of eco-friendly biocatalysts, but also positions them as a viable alternative material for the sustainable production of hydrogen via NaBH₄ methanolysis.

Three significant parameters contribute to the value and renewability of this study. The first is that waste is used as the primary material; the second is that the activator is less hazardous than other activators; and the third is that microwave activation is a green chemistry technique.

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