فهرست مطالب

Advanced Ceramics Progress
Volume:10 Issue: 3, Summer 2024
- تاریخ انتشار: 1403/11/13
- تعداد عناوین: 6
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Pages 1-7
This paper explores α/β-SiAlON composites, known for their exceptional mechanical and thermal properties, fabricated using spark plasma sintering (SPS). Novel reagents were initially introduced for the mechanochemical synthesis of precursors essential for producing α- and β-SiAlON phases via the carbothermal process. The prepared precursors were combined with active carbon in stoichiometric ratios and heated in a nitrogen (N₂) atmosphere for two hours. Characterization techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM), confirmed the successful synthesis of SiAlON phases at 1500°C, revealing a range of morphologies.The results demonstrate that all composites sintered through the SPS process achieve complete densification at 1800°C. Mechanical properties, such as hardness and fracture toughness, are influenced by the ratios of α- and β-SiAlON phases. A composition of 70% β-SiAlON and 30% α-SiAlON exhibited optimal results, achieving a fracture toughness of 4.67 MPa•m¹/² and a hardness of 17.32 GPa, comparable to commercial samples produced using alternative raw materials.
Keywords: Sialon Composites, Novel Precursors, Spark Plasma Sintering, Carbothermal Reduction, Nitridation Process, Mechanical Properties -
Pages 8-14In this study, ZrB2-SiC ultra-high temperature ceramic composite was sintered using Spark Plasma Sintering (SPS) process with WC/HfB2 modifiers at different sintering temperatures of 1850, 1900, 2000, and 2050˚C for 8 and 25 minutes. The densification behavior of the composite was also examined using punch displacement-time and temperature-time measurement graphs during SPS. Phase and microstructure evaluations were also done based on XRD, EDS, and FESEM methods. The effect of SPS parameters on the densification of ZrB2-SiC-based composite was studied. In this case, there was no displacement until the pressure was applied due to the low sinterability of boride powders. A ZrB2-SiC-based composite with a relative density of 90% was obtained at 2050˚C under 30 MPa for a 25-minute soaking time. The densification curve of this sample showed a typical “S” shape. The best water absorption and apparent porosity values obtained as 1.3 and 6.7%, respectively. The minimum and maximum punch displacement of the samples was 2.2 and 3.6 mm, respectively. Use of WC/HfB2 modifiers led to the formation of byproducts of WB and HfB.Keywords: Zrb2, Densification, Spark Plasma Sintering, Porosity, Density
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Pages 15-22In this study, cadmium tungstate (CdWO₄) and silver-doped cadmium tungstate (CdWO₄:Ag)/polyvinyl alcohol (PVA) nanocomposite films were successfully fabricated. The preparation of the nanocomposite films was accomplished through a straightforward hydrothermal procedure following an established protocol. XRD, EDX, and Fourier-transform infrared (FTIR) spectroscopy confirmed the successful synthesis of CdWO₄ and CdWO₄:Ag nanopowders. FESEM images revealed mean particle sizes of approximately 345 nm for CdWO₄ and 267 nm for CdWO₄:Ag nanopowders, respectively. The luminescence characteristics of the synthesized nanoparticles were evaluated under UV irradiation. The CdWO₄:Ag nanoparticles exhibited significantly higher luminescence intensity within the blue-green spectrum compared to the pure CdWO₄ sample. The radiative response of the samples was meticulously assessed using an (²⁴¹Am) alpha source, with the doped sample demonstrating a marked improvement in the count rate compared to the CdWO₄ composite. Furthermore, the CdWO₄:Ag composite exhibited acceptable counting efficiency, performing at levels comparable to more expensive alpha counters. These findings suggest that the CdWO₄:Ag/PVA nanocomposite holds significant potential as an effective scintillation material optimized for radiation detection applications.Keywords: Cdwo4, Silver Dopant, Co-Precipitation, Nanoparticles, Scintillation Properties
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Pages 23-36
The biocompatibility of coatings applied to implants is a critical factor in ensuring optimal implant performance and patient safety. Recent studies have highlighted the significant impact of protein interactions on the biocompatibility of these coatings. This review aims to provide a comprehensive overview of the current understanding of how proteins influence the biocompatibility of coatings applied to implants. The biocompatibility of these coatings is affected by various factors, including the type and concentration of proteins present in the surrounding environment. Proteins can interact with the coating material, altering its surface properties—such as hydrophilicity, roughness, and charge—and subsequently affecting the host response,including inflammation, fibrosis, and osseointegration.Protein adsorption onto the surface forms a layer that mediates blood cell adhesion and cellular responses, significantly influencing the surface's biocompatibility. This review emphasizes the dual nature of proteins: while some enhance biocompatibility by promoting cell adhesion and proliferation, others may induce adverse effects. The article explores the mechanisms through which proteins interact with coatings and discusses how these interactions can be optimized to improve biocompatibility. Finally, the review highlights the potential of protein-modified coatings to enhance both biocompatibility and functionality in various implant applications, including orthopedic and cardiovascular implants. Such coatings demonstrate the ability to improve cell adhesion, promote tissue integration, and reduce inflammatory responses.
Keywords: Implant Advanced Coatings, Protein Interactions, Biomaterials, Cell Adhesion, Tissue Engineering -
Pages 37-44In this study, nanostructured thermal barrier coatings (TBCs) were fabricated using the Spark Plasma Sintering (SPS) method on an Inconel 713 LC superalloy substrate. These coatings were compared to those produced by Atmospheric Plasma Spray (APS) in terms of mechanical properties. The aim of this study was to investigate and optimize the process parameters to improve the microhardness of these coatings. Key parameters, such as temperature, pressure, and holding time, were optimized using the Taguchi design of experiments (L9). The results showed that SPS coatings exhibited significantly higher hardness compared to APS coatings, due to a notable reduction in porosity and increased density. The highest microhardness achieved for SPS coatings was 700 HV at a temperature of 1080°C, a pressure of 25 MPa, and a holding time of 6 minutes. In contrast, APS coatings demonstrated lower hardness, primarily due to higher porosity and lower density. This study highlights that precise control of process parameters in the SPS method can produce coatings with enhanced mechanical properties, making them suitable for high-temperature applications in aerospace and power generation industries. Furthermore, the Taguchi method effectively reduced the number of experiments and improved process efficiency.Keywords: SPS, Microhardness, Nanostructured Thermal Barrier Coatings, APS, Taguchi Design
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Structural and Magnetic Characterization of Cobalt Ferrite Nanofibers Produced by Electrospinning MethodPages 45-51
Cobalt ferrite, with the general formula CoFe₂O₄, exhibits unique magnetic properties such as high magnetocrystalline anisotropy, high coercive field, intermediate saturation magnetization, and excellent physical and chemical stability. Moreover, the use of nanofibers in the field of magnetic materials is increasingly popular due to their high surface-to-volume ratio, low weight, high porosity, and considerable shape anisotropy. In this research, cobalt ferrite nanofibers with different diameters were produced via electrospinning using a solution containing 8 wt% polyvinylpyrrolidone, with the applied voltage being optimized. Based on the results of energy dispersive spectroscopy (EDS), the presence of Fe, O, and Co elements in the structure of the cobalt ferrite nanofibers was confirmed. Additionally, X-ray diffraction (XRD) analysis revealed that the cobalt ferrite nanofibers are formed in a single phase after calcination at 800 °C. Field emission scanning electron microscopy (FE-SEM) images showed that, by optimizing the applied voltage between the nozzle and the collector, the average diameters of the cobalt ferrite nanofibers were varied between 86 nm and 171 nm. According to vibrating sample magnetometry (VSM), the saturation magnetization, residual magnetization, and coercive field of the optimized sample were measured as 85 A·m²/kg, 61 A·m²/kg, and 1.32 × 10⁵ A/m, respectively. First-order reversal curve (FORC) results showed that increasing the average diameter of the fibers raises magnetostatic interaction. Based on the results of this research, the production of cobalt ferrite nanofibers using the electrospinning method is feasible. Compared to similar studies, higher values of saturation magnetization and coercive field were obtained in this work.
Keywords: Cofe₂o₄, Electrospun Fibers, Magnetic Ceramics, Nanomaterials