Journal of the Australian Ceramic Society最新文献

The hydroxyapatite (HA) powder is successfully synthesized from calcined eggshell by the hydrothermal reaction method. The colloidal solution made of calcined eggshell powder, tricalcium phosphate powder, and demineralized water is kept in a closed ceramic vessel to perform hydrothermal reactions. For this purpose, different temperatures (700 - 1000 °C) for various time durations (1, 2, and 3 h) are applied to the solution. X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS) are employed to characterize the prepared powders. The synthesized powders are further assessed in terms of crystalline phase, microstructure, crystallite size, particle size, Ca/P ratio, and crystallinity. In all the reaction products, majorly the HA powders are obtained. The spherical HA grains are found to have a tendency to agglomerate at higher reaction temperatures and times. The applied temperature and heating duration are found to be the crucial parameters that control the properties of the synthesized HA. The HA with the largest crystallite size is obtained from 1000 ^oC of heating temperature applied for 3 h. However, the HA with high crystallinity is obtained from 800 ^oC temperature applied for 1 h of time. Non-stoichiometric HAs are obtained from all different reaction temperatures and time durations. Mostly Ca-rich (Ca/P > 1.67) HAs are formed in all powders except the one prepared at 900 ° C, where the formation of Ca-deficient (Ca/P < 1.67) HA is noticed. The near-stoichiometric HA can be produced from 900 ^oC of reaction temperature applied for 1 h. The study illustrates that HA can be synthesized successfully from chicken eggshell by hydrothermal reaction method in less time by applying high heating temperature.

Many natural systems more often than not exploit some intricate structures to meet up with functionalities that surpass those sourced from man-made origin. So, elucidating how these biological systems attain mechanical functionalities is crucial to establishing a sustainable route for the production of naturally derived scaffolding materials. In this contribution, variants of hydroxyapatite (HAp)-derived scaffolds characterized by different unique morphologies were fabricated through direct mechano-chemical conversion of catfish and non-separated animal bones by the regulation of reaction temperatures. The representative scaffolds were prepared by cold compaction and sintered at 900, 1000, and 1100 °C. The fabricated scaffolds produced distinct crystal morphologies with a composite of micro- and nano-dimensional structures in the shape of rods and flowers. Energy dispersive spectroscopy (EDS) analysis was used to estimate the calcium-to-phosphate ratios, while acoustic emission was used to detect the crack propagation behavior of the scaffolds. Porosity evaluation was conducted, while the antimicrobial properties of comparatively better scaffolds were investigated using the disc diffusion method. The obtained experimental results showed that at 900 °C, optimum properties were obtained with a Ca/P ratio of 1.53 for the CB-900 sample representing a calcium-deficient scaffold with potential tissue engineering applications. The crack propagation data showed relatively lowest activity for the CB-900 sample with notable activity for two bacterial strains.

Abstract

Over the years, hydroxyapatite (HAp) has been a well-researched biomaterial because of its bioactive and biocompatible properties with remarkable applications for bone tissue engineering. The robust structure of HAp allows for a host of applications in biomedicine. HAp is enriched in calcium and phosphate, can be sourced from synthetic or natural precursors with significant characteristics notable of biomaterials, and can be produced by facile protocols for clinical use. Nonetheless, HAp prepared from natural or synthetic sources are different due to the conditions of processing. One of the factors in this direction and for the high performance of bioceramics in biomedicine is a robust mechanical strength that prevents failure of the HAp scaffolds. Stemming from these, and of particular interest, is the porosity of the HAp-derived scaffolds that plays a major role in the mechanical properties in vitro and in vivo. Many reports have it that there are reduced mechanical properties vis-à-vis the inherent high porosity of the scaffolds, and these must be balanced in line with the degradation rate of the scaffolds. Gradients in pore sizes and crack propagation tendencies are important to lead to new production methods with the potential to generate scaffolds with morphological and mechanical properties designed to meet bone repair needs. Nowadays, validating mechanical and materials engineering properties with the aid of atomistic simulations using density functional theory (DFT) and artificial intelligence (AI), and the complement of experimental studies, is gradually becoming an important research domain within the scientific community. The importance of these theoretical and AI methods can be ascribed to the comprehension of the non-linear relationship between some measured properties using experimental datasets. Hence, this review explores a re-cap and the state of knowledge regarding sustainable natural sources of HAp, data on mechanical property measurements, the link between porosity and mechanical properties of HAp-derived materials for bone tissue engineering, a relatively new method for characterizing the mechanical behavior of HAp, computational trends in biomaterials research, and recent trends on the biomedical applicability of HAp.

In recent years, environmental problems arising from the gradual depletion of natural resources and the rapid increase in waste generation have brought recycling and waste management into focus. Since wollastonite (CaSiO₃) as a calcium silicate ceramic is a bioactive material used in various fields, its synthetic production attracts attention. Therefore, the present study aims to produce bioactive wollastonite from marble and quartz wastes as industrial wastes with a 3-step technique from the green perspective. In addition, the effects of production parameters including sintering temperature (900 1000, 1100, 1200, and 1300°C), sintering time (2, 6, and 12 h), and milling time (0.5 and 12 h) on the phase and morphological structure, biocompatibility and bioactivity of the obtained synthetic wollastonite were investigated comparatively in the study. Accordingly, raw waste materials were first characterized with X-ray fluorescence (XRF), thermogravimetric analysis (TG/DTG), X-ray diffractometer (XRD), and scanning electron microscopy (SEM), respectively. TG/DTG results were used to optimize sintering temperatures of the CaO:SiO₂ (with 1:1 molar ratio) aqueous mixtures. The resulting powders were also analyzed using XRD, FTIR, and SEM. Structural characterization revealed that the formation of wollastonite (CS) phases and the polymorphic transformation reaction (from β-wollastonite to α-wollastonite) are affected by sintering and milling time as well as sintering temperature. By adjusting the milling and sintering time, a high-temperature phase α-wollastonite can be synthesized at a relatively low temperature of 1000°C, when β-wollastonite begins to transform. The biocompatibility of the wollastonite powder extracts was evaluated on mouse fibroblast, L929 cell lines by MTT assay and the changing in the phase of quartz by temperature, sintering and milling resulted with increased biocompatibility of the wollastonite powders. The obtained in vitro mineralization results after soaking of the wollastonite powders for 1, 3, and 7 days in SBF proved that SW exhibited good bioactivity due to the formation of spherical-shaped carbonated hydroxyapatite.

In this study, the use of rheologically problematic carbonate-bearing clay from the Bilecik and Çanakkale Region of Turkey in porcelain tile bodies was investigated using the dry preparation method. Firstly, the chemical–mineralogical and technological properties of clays were determined, and characterization studies were performed. Then, an attempt was made to determine the optimum usage possibilities by using these raw materials instead of the standard clay-kaolin mixture raw material at the ratios of 10, 20, 30, and 40% in the standard porcelain tile structure. The sintering behavior of the standard bodies, carbonatic clay containing bodies, was studied comparatively using a double-beam optical non-contact dilatometer. Shrinkage (%), water absorption (%), bulk density (gr/cm³), dry strength (N/mm²), flexural strength (N/mm²), and color L, a, b tests were performed on the developed bodies. Mineralogical and phase analyses have been carried out by XRD. The results showed that carbonatic clays, which have rheological problems, could be used in porcelain tiles with dry preparation systems.

In this study, waste glass obtained from a discarded green glass bottle and unexploited natural red soil (RS) were prepared to get glass–ceramic foams. Red soil is an earthy material, which is used as a foaming agent. A mixture of starting powders containing different mass fractions (5–16 wt.%) of RS with particle size smaller than 20 μm was uniaxially pressed (at 30 MPa), and the obtained compacts were fired at different temperatures (750–850 °C) and holding time (30–120 min). Furthermore, the influences of temperature, holding time, and natural rock additions on the structure, type, and size of pores, besides physical and mechanical properties of the processed foamed glass–ceramic samples, were investigated. The results show that the optimum foaming temperature was found to be 800 °C leading to a maximum value of porosity as high as 90%, while the bulk density and compressive strength reached the values 0.26–0.75 g·cm⁻³ and 1.2–6.1 MPa, respectively. Based on the present data, the obtained glass–ceramic allowed the preparation of different porosity types. Therefore, they provide practical value for specific applications where thermal insulation is desired.

Qandilite Mg₂TiO₄ ceramic was prepared from MgO-TiO₂ powder/borosilicate glass composite. Composite materials were prepared by nominal MgTiO₃ alone and with 10, 30, and 50% borosilicate glass. The sintering process resulted in qandilite alone either in nominal Mg₂TiO₄ alone or with 10% glass. Incorporation of 30% and 50% glass gave crystalline magnesium titanate (MgTi₂O₅) in both sintered samples with either forsterite (Mg₂SiO₄) in 30% containing glass or rutile (TiO₂) and enstatite (MgSiO₃) in 50% containing glass. The microstructure of sintered samples presented clear tetragonal or octahedral which referred to qandilite in the case of nominal MgTiO₃ alone or that containing 10% glass. Also, the later crystals appeared in the case of 70% glass-containing samples whereas in the case of 50% containing glass, in addition to the later clear crystals, rod-like crystals were embedded in glassy matrix. The dielectric constant of the studied composite samples was decreased with increasing the glass fraction until 30 wt%, and then increased to lead to the highest values of dielectric constant (⁓125 at room temperature and 1 kHz) at a glass fraction of 50 wt%. The activation energy (E_a) attained values in the range 0.145–0.438 eV. The results of E_a values and AC conductivity may indicate the dominance of electronic mechanism over the ionic transfer one in the studied sample. The prepared composite samples exhibited a semiconducting nature.

MgAl₂O₄ spinel matrix nanocomposite with TiC, AlTi₃, and Al₂O₃ was directly fabricated using the mechanical alloying (MA) method with Mg, TiO₂, Al, and graphite as the starting powder mixture. This methodology was used to synthesize magnesium aluminate spinel (MSA) matrix nanocomposite with having the advantage of no subsequent heat treatment. The mixture of the powders was milled at room temperature using a high-energy planetary ball mill with a vial rotation speed of 400 rpm in the air. The phases and morphological analysis after the MA process were characterized by X-ray diffraction and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). Followed by 20 h of ball-milling, all the desired phases of MgAl₂O₄, TiC, AlTi₃, and Al₂O₃ appeared in XRD results, and also a small fraction of raw materials remained. The major reactions to synthesize MgAl₂O₄/TiC-AlTi₃-Al₂O₃ spinel matrix nanocomposite were the reduction of TiO₂ by Al and Mg.

In this work, the effects of Co_xZn_1-x Fe₂O₄ (x= 0, 0.5, 1) nanofillers on the PVDF polymer were scientifically studied. The structure and magnetic and optical properties were studied. XRD confirms the synthesis of nanofiller in a single phase. FTIR confirms the formation of nanoferrites. HRTEM shows that the prepared nanoferrites have a cubic-like shape. Also, the size and agglomeration increase with Co-Zn Fe₂O₄ nanoferrites compared to the other singles one. The effect of adding nanoferrites into PVDF matrix was studied using XRD, FTIR, FESEM, VSM, and UV-Vis. XRD and FTIR approved the complexation between PVDF polymer and nanoferrites. Also, addition of nanoferrites into PVDF leads to decrease the semi-crystalline nature of PVDF. FESEM showed that embedding nanoferrites into PVDF polymers creates pores and PVDF/Co-Zn Fe₂O₄ increases the pore size on the PVDF surface. The magnetic properties of PVDF were enhanced by adding the nanofiller. For example, saturation magnetization was increased from 269.31E⁻⁶ to 62.052E⁻³ by adding CoFe₂O₄ to PVDF polymer. Band gap calculation showed that PVDF/Co-Zn Fe₂O₄ has the lowest band gap energy which makes it useful in photochemical and electronic applications.