Advanced Ceramics Progress
Volume:5 Issue: 4, Autumn 2019

In this study, an industrial polycrystalline SiC tile was successfully sintered by pressureless sintering at 2150°C for 1 hour. The physical and mechanical properties of silicon carbide including density, hardness, bending strength, and fracture toughness were evaluated. The results indicated that the mentioned properties were 3.08 g.cm-3, 2503 HV0, 249.3 MPa, and 1.23 MPam0.5, respectively. The mechanical properties of samples showed that strength, hardness, and fracture toughness were low, indicating samples are inappropriate for industrial applications. It seems that the use of pressure-assisted sintering such as spark plasma sintering or sintering with the use of sintering aid materials such as alumina and yttrium oxide in the structure of the specimen, will improve the physical and mechanical properties of the sample.

The Chalcogenide glasses were fabricated by melting and quenching techniques in the Se-Ge system at the presence of 1mol% Ga and 3, 5, and 7mol% Sn. Differential Scanning Calorimetry (DSC) analysis was conducted to extract the heat treatment of the samples. Fourier Transform Infrared (FTIR) spectroscopy analysis was also performed in a range of 2-16µm. The Glass samples were heat-treated at 450°C for 1-10h. The precipitated nanoparticles were observed using a Field Emission Scanning Electron Microscope (FESEM). The crystal size was reported in the range of 100-1000nm. The precipitated phases were identified using X-ray Diffraction (XRD) analysis on Glass-Ceramics powder. The increase in hardness of the Glass-Ceramics was reported in the range of 200-250Kg.mm-2.

Using flawless components are important for a proper material selection and best working conditions to achieve the best performance of solid oxide fuel cells (SOFCs). Tape casting is the most used process for the fabrication of SOFC parts, especially anode and electrolyte due to its advantages regarding the other processes. In this study, the effect of slurry composition and milling time were successfully investigated on anode and electrolyte tapes defects. The results showed that the addition of terpineol to electrolyte slurry as a dispersant would reduce the size of agglomerates to 5μm. Furthermore, 6h of ball milling showed the optimum result for the anode slurry due to the disappearing of island defects, which agrees well with optical microscopy images of samples with minimum apparent defects on the surface. Afterward, the optimum tapes of anode and electrolyte were laminated and sintered at 1400°C for 4h. Half-cells had minimum apparent deformations and surface defects after sintering. Scanning electron microscopy images exhibited a uniform distribution of porosities without any separation in anode layers, as well as the full dense electrolyte.

Bioglass-graphene oxide composites can be served as an appropriate alternative for bone implant applications due to its specific mechanical properties. In this study, the 45S5 bioactive glass (BG) - graphene oxide (GO) composite containing 2wt% GO was deposited on the Ti-6Al-4V alloy substrate via the electrophoretic deposition process (EDP). The synthesized GO was incorporated into BG coating to improve the mechanical properties. The phase, structural agents, microstructure, and composition were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), respectively. The micro scratch test with a progressive load was applied to study the adhesion and fracture toughness of coatings based on a linear elastic fracture mechanics model. micro scratch results showed the highest critical distances of crack initiation and delamination, critical contact pressures (Pc1 and Pc2= 4.80 and 5.37GPa, respectively), and fracture toughness (KIC= 0.885 MPa.m1/2) for BG-GO composite coatings.

In this report, ultraviolet (UV) detectors were fabricated based on zinc oxide thin films. The epitaxial growth of zinc oxide thin films was carried out on a bare glass substrate with a preferred orientation to (002) plane of wurtzite structure through radio frequency sputtering technique. The structural properties indicated a dominant peak at 2θ=34.28º, which was matched with JCPDS reference card No. 34-1451 and showed the wurtzite phase of deposited ZnO thin films. This peak showed the preferred orientation with the c-axis perpendicular to the surface. The crystallite size was estimated using the Scherrer equation as much as 44.5nm. The morphology of samples showed that pebble-shaped ZnO particles were covered on the entire substrate homogeneously. The results indicated the excellent optical properties in the visible-infrared region with high absorption in the UV spectrum. The extrapolated cut-off for the transmittance spectrum was at 373nm, which confirmed the calculated optical bandgap of this sample at 3.27eV. The optical properties showed that the deposited samples are suitable substrates for the fabrication of UV detectors. Two back-to-back Schottky contacts of Au were deposited on the ZnO substrate to fabricate UV detectors, and a metal-semiconductor-metal structure was designed. The optoelectrical properties of detectors were carried out using the measurement of current-voltage curves. The results indicated a high photosensitivity of 0.32 corresponding to the high performance of the fabricated device. Moreover, the device showed a short rise time of 0.40s and recovery time of 0.45s indicating the high speed of detection for fabricated UV detectors.

In this research, a thin film of TiO2 was applied on AZ91D using the method of magnetic sputtering. Microstructure investigations were conducted using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). Wear resistance for the coating was investigated using the pin on the disk in the form of dry and in the Ringer's solution. the worn surface of the samples was investigated using scanning electron microscopy (SEM) asfter this test. Meanwhile, the level of hardness and flatness of the surface after coating was investigated using Vickers microhardness tester and roughness tester. Results indicated that the coating was formed uniformly and had the globular morphology and very good coherence with the thickness of 90nm, which is seemingly formed at the interface of the coating and substrate of the MgTi2O5 and Mg2TiO4 spinels. The roughness of the surface decreased as much as 20% by applying the coating. Applying the coating decreased the coefficient of friction and increased wear resistance in both of the environments. Following the application a thin film of TiO2, wear mechanism was transferred from severe abrasive to mild abrasive in the dry environment and cleavage crater in the Ringer's solution.