Journal of the Australian Ceramic Society最新文献

This is the first report, including both theoretical and experimental results, on Bi and Sn co-doped hydroxyapatite (HAp) structures. Sn content was kept at a constant amount of 0.22 at.%, and Bi content was changed from 0 to 0.44 at.% by using the steps of 0.11at.%. Theoretical results from density functional theory (DFT) calculations revealed an increase in density from 3.154 g cm⁻³ to 3.179 g cm⁻³, as well as gradual decreases in the bandgap from 4.5993 eV to 4.4288 eV and the linear absorption coefficient. The spectroscopic data obtained from both Raman and Fourier transform infrared (FTIR) spectra confirmed the HAp structure for all the samples. The thermal behavior and morphology, as well as all X-ray diffraction (XRD) related parameters, were all considerably impacted by Bi-content. In vitro assays showed that all the samples can be accepted as the biocompatible materials.

Abstract

In order to improve the hardness and wear resistance of cold work molds, La₂O₃-reinforced WC − 10Co4Cr − Al₂O₃ coatings were fabricated on Cr12MoV steel by laser cladding (LC). The morphologies, grain sizes, and phases of obtained coatings were analyzed using a digital microscopic system (DMS) and X-ray diffraction (XRD), respectively. The effects of La₂O₃ mass fraction on the tribological performance and wear mechanism of WC − 10Co4Cr − Al₂O₃ coatings were analyzed using a ball-on-disk wear tester. The results show that the La₂O₃-reinforced WC − 10Co4Cr − Al₂O₃ coatings are composed of WC, W₂C, Al₂O₃, La₂O₃, LaAlO₃, and Fe − Cr, AlP₃Si, LaCoO₃, and LaP phases, and the hardness of obtained coatings increases with the increase of La₂O₃ mass fraction. The average coefficients of friction (COFs) of WC − 10Co4Cr − Al₂O₃ − 3%La₂O₃, − 6%La₂O₃, and − 9%La₂O₃ coatings are 0.57, 0.52, and 0.46, respectively; and the corresponding wear rates are 63.18, 47.1, and 27.99 μm³•s⁻¹•N⁻¹, showing that the friction reduction and wear resistance of WC − 10Co4Cr − Al₂O₃ − 9%La₂O₃ coating are the best among the three kinds of coatings, and the grain refinement and dispersion strengthening by the addition of La₂O₃ are the main factor affecting its wear resistance.

Abstract

Transparent sodium phosphate glass–ceramics system according to the composition (55-x) P₂O₅.(30 + x)ZnO.15Na₂O where x = 0, 2.5, 5, 7.5, and 10 was prepared with the melt quenching technique. Different techniques such as XRD and infrared spectroscopy (FTIR) were used to investigate the structure of the studied glass samples and glass–ceramics nano composite. XRD revealed the formation of crystalline phase. The crystalline phase of Na₂Zn (P₂O₇) and Na₂ZnP₂O₇.Zn₂P₂O₇ has been detected which varies according to the ZnO concentration. The density increased whereas molar volume decreased as ZnO content was increased. Optical band gap values, direct and indirect, decreased with increasing ZnO content revealing that bridging oxygen linkage Zn–O-P present in the glass network. The band gaps were found to be ranging between 3.42 and 3.13 eV for indirect transition and ranging between 4.34 and 4.20 eV for direct transitions. It was concluded that the samples have a strong tendency to be crystallized with increasing ZnO content in the sample. This crystallization behavior with increasing the ZnO content affected the structure and optical properties of the prepared samples. In this work, a low cost, wide band gap transparent ceramic with wide range of transparency was prepared and investigated. Such glass–ceramic system is suitable for doping with rare-earth element and/or transition metals for laser and optical devices.

To effectively reduce the heat loss of high-temperature thermal equipment, it has become a mainstream trend to develop lightweight refractories with low thermal conductivity and high strength as thermal insulation linings. The pore size of traditional lightweight refractories is dominated by micron-level pores. In this study, a lightweight magnesia refractory with a double pore size (micron-nanometer) was prepared by the sol impregnation process. The formation mechanism of the nano pore was proposed, and the influence of sintering temperature on the microstructure, sintering performance, and thermal physics property of the sintered samples was investigated. The results showed that the bulk density of the lightweight magnesia refractories with nano pores (500–800 nm) increased from 1.26 to 1.94 g/cm³, the apparent porosity from 64.73 to 43.86%, and the cold crushing strength increased from 4.9 to 21.4 MPa during the increasing the sintering temperature from 1300 to 1600 °C. The average thermal conductivity of the sample at 1300 °C was 0.438W·m⁻¹·K⁻¹. The nano-MgO increased the migration distance with the periclase particles, and the number of nano pores was increased. In addition, the surface stress of the magnesia sol increased the speed of boundary migration and closed the pores before they were eliminated, and the formation of intercrystalline nano pores. The presence of nano-MgO can refine the pores, so that lightweight magnesia has lower thermal conductivity and excellent strength.

A hydrophobic non-woven fabric was fabricated using candle soot coatings. The coated fabric (CS-fabric) was hydrophobic and oleophilic. CS-fabric maintained a water contact angle of 142° over a longer period showed its durability. It exhibited high oil–water separation efficiency (95%) for the petrol-water mixture. CS-fabric (5.0 × 3.0 cm²) was able to completely adsorb RB from 20 ml of dye’s aqueous solution within 30 min. Moreover, CS-fabric can be reused up to several cycles as it showed promising cyclic adsorption performance even after five cycles. It can also (single layer) completely adsorb detergent from detergent solution (concentration 0.5 g/l) within 60 min. The kinetic study showed that the pseudo-second-order kinetic model fitted best to the kinetic data.

The recovery of agro-food waste was one of the challenges during the last decades. In this context, the aims of the current study are the evaluation and the comparison between two resources of bone that are dromedary and bovine bones. A biomaterial was prepared from the two bone’s resources by heat treatment at different temperatures and characterized by physicochemical techniques to determine the effect of bone’s type in physicochemical properties of hydroxyapatite. The obtained results of FTIR and XRD showed the removal of all organic matter and the production of pure hydroxyapatite without any additional phase for both types of bone. The laser particle size analyzer indicated that hydroxyapatite’s particle size increases when the temperature is increased. The XRF tests results revealed that the bone type significantly affects the concentration of hydroxyapatite compounds.

The effect of CaO/SiO₂ ratio on the crystallization behaviors, mechanical properties, and acid and alkali resistance properties of the prepared Ti-bearing blast furnace slag-based glass ceramics were investigated. The results showed that the crystallization temperature obviously decreased with the increase of CaO/SiO₂ ratio, and the higher CaO/SiO₂ ratios leaded to stronger crystallization ability. The main crystal phases transformed from CaAl₂Si₂O₈ and CaMgSi₂O₆ to CaAl₂Si₂O₈, CaMgSi₂O₆, and Ca₂MgSi₂O₇ as the CaO/SiO₂ ratio increased from 0.3 to 0.6. When the CaO/SiO₂ increased to 0.5, a small amount of akermanite precipitated. The vickers hardness gradually decreased, and the flexural strength first increased and then decreased with an increased CaO/SiO₂. The glass ceramic with CaO/SiO₂ = 0.5 exhibited the highest flexural strength of 109.58 MPa. The prepared glass ceramics showed good acid and alkali resistance (> 98.30%), especially alkali resistance. Therefore, the best candidate for CaO/SiO₂ ratio in the investigated Ti-bearing blast furnace slag-based glass ceramics was selected as 0.5. This work can provide the reference for preparation slag-based glass ceramics.

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