Advanced Ceramics Progress
Volume:9 Issue: 2, Spring 2023

The anodizing process of titanium (Ti) implants and their alloys improves their corrosion resistance and life service by naturally increasing the thickness of the passive oxide layer formed on the surface. Among the parameters that affect the properties of the anodized layer, voltage is a significant one due to the kinetic and thermodynamic processes. In this paper, commercial pure titanium (cp-Ti) coupons with the dimensions of 20 ×10 × 1 mm3 were used as the anode in 1 M sulfuric acid solution at different voltages of 3, 6, and 9 V, current intensity of 3 A, electrolyte temperature of 60 °C, and duration time of 30 s. The phase composition analysis, morphology, and corrosion behavior of the anodized Ti were examined by Grazing‐Incidence X‐Ray Diffraction (GIXRD), Field‐Emission Scanning Electron Microscopy (FESEM), and electrochemical impedance, respectively, in Simulated Body Fluid (SBF) at 37 °C. The results confirmed the formation of titanium oxide coating with a hexagonal structure. A smoother surface was obtained upon increasing the voltage up to 6 V. However, the surface became rougher with further voltage increase up to 9 V. The highest charge transfer resistance (37354 and 58127 ohm.cm-2) was achieved at 6 V after 1 and 24 hours of immersion in the SBF solution, representing 84 % and 2440 % increase, respectively, compared to the cp-Ti sample. The double layer helps prevent the formation of localized corrosion sites, such as pitting and crevice corrosion, which can be particularly damaging to Ti alloy as an implant in the human body. Although rising the voltage from 3 to 6 V resulted in a more hydrophobic surface (as shown by an increase in the contact angle from 63.8° to 74.1°), further voltage increase up to 9 V made the surface more hydrophilic than before.

This study investigated the flowability and compactability of the milled Ti-Cu alloys as a new version of biomedical alloys used for fabrication via Additive Manufacturing. In this study, Ti- 50 at. % Cu powder was first milled for different durations, and the morphology, microhardness, size, flowability, and compactability of the powder were assessed. The results indicated that while flowability increased with prolonged milling time, compressibility decreased owing to a decrease in the plastic deformation capacity. The highest flowability level was obtained when hard TiCu phase was synthesized after 30 hours of milling. Different linear and nonlinear compaction equations were used to investigate the densification response of TiCu powder in a rigid mold during uniaxial compression. Cooper-Eaton nonlinear equation was found to be the best fit compared to the linear equation. The contribution of particle rearrangement to the densification behavior was high, and it increased upon increasing the applied pressure. At pressures below 1200 MPa, the contribution of plastic deformation to the powder densification was negligible.

Garnet-type Li7La3Zr2O12 (LLZO) solid-state electrolytes are promising candidates for application in next-generation solid-state batteries. Of note, the most controversial issue is to stabilize the cubic phase structure (c-LLZO) with high density after the sinter process to reach high ionic conductivity with the desired strength. Considering this issue, the current study aims to investigate the synthesis and sintering of LLZO with Al substituted and without any additive. The LLZO ceramic was synthesized through conventional solid-state reaction. The effect of heating temperature on the synthesis of the cubic structure was studied using X-Ray Diffraction (XRD). The ionic conductivity of the samples was examined by AC Impedance Spectroscopy. The obtained results indicated that Al doping led to the cubic phase stabilization and that it had a positive effect on the sintering regime so that the sample with Al dopant was densified at the lower temperature of 1140 °C. The total ion conductivity of Al-LLZO is 0.1 mScm-1 which is comparable to the values of high temperature-sintered samples.

Ceramic nozzles are unique options in aerospace industry due to their ability to operate at high temperatures. However, their brittleness, structural defects, poor formability, and need for complex methods for measuring their mechanical properties are among the main obstacles to their development. In this study, four different conical nozzles were produced through Plasma Spray Forming (PSF). Given that Yttria-Stabilized Zirconia (YSZ) is one of the most common materials in high-temperature applications, it is considered as the base material. Throughout the research, three YSZ alternatives were investigated by changing the chemical composition (Ceria-Yttria co-Stabilized Zirconia (CYSZ)), by changing the particle size (nanostructured YSZ), and by double layer architecture design. The mechanical properties of the conical nozzles were then evaluated by the nanoindentation test using Oliver and Pharr method. This method can be quick and applicable for evaluation of the mechanical properties of ceramic parts based on the load-depth curve. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were performed for the phase analysis and coating microstructure and porosities investigation. The results highlighted the promising features of nano-structured YSZ that are strongly based on the presence of nano-zones inside the coating structure.

Flutter is an example of an aero-elastic phenomena that involves analyzing the interaction between elastic and aerodynamic forces, both static and dynamic. This study examined the effects of the stacking of polymer and aluminum layers on the modal frequency, drop weight impact, and tensile characteristics of polymeric composites and Fiber Metal Laminates (FMLs) incorporating carbon fibers. In this study, Carbon Fiber Reinforced Plastic (CFRP) laminates were used in the FML composite specimen. Based on a hand-lay-up method, 20 layers of carbon fiber prepregs were used to fabricate the specimen, i.e., Al/4CFRP/Al (Al2C1) and then, Al/4CFRP/Al/4CFRP/Al (Al3C2) fiber metal laminates with two stacking arrangements were made. The surfaces of the aluminum sheets were treated through an anodizing method to improve the adhesion between aluminum and polymer layers. The fracture surface of the specimen was investigated using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). The mechanical properties along with the vibration behavior of specimen were also studied accordingly. The results showed that Al3C2 had the greatest values of the required frequency for vibration and lowest stress brought on by vibration, with 0.0008 MPa for the initial state. Additionally, the FML sample demonstrated a higher frequency and less stress from vibration than the CFRP specimen with the same thickness. According to the findings of the impact tests, CFRP and Al3C2 had the lowest (210 KJm-2) and the highest (960 KJm-2) values, respectively. However, due to the lower weight of Al2C1 than that of Al3C2, the specific absorbed energy value of the former was higher (4.7 Jm2kg-1) than that of the latter (2.3 Jm2kg-1). In tensile testing, Al3C2 was characterized by the best tensile properties (i.e., yield strength of 580 MPa and ultimate tensile strength of 897 MPa) compared to other samples. The current study demonstrated that compared to other specimen, Al3C2 possessed the least potential to flutter occurrence in a possible real situation.

Magnetic hyperthermia is a promising cancer treatment approach in which magnetic nanoparticles are used, offering unique properties such as higher penetration depth and precise thermal control that make them effective for cancer treatment. In addition, the sensitivity of cancer cells to heat and the role of magnetic nanoparticles are very effective in combined treatments. Here, CoFe2O4 nanoparticles are synthesized using a co-precipitation method under gas atmosphere during the synthesis process. The characteristics and properties of the synthesized nanoparticles are investigated using XRD, FESEM, and VSM analyses. The XRD results confirm the formation of cobalt nanoparticles. FESEM investigations reveal that the nanoparticles have uniform surface morphology and spherical shape. The VSM results show that the CoFe2O4 nanoparticles possess superparamagnetic properties as confirmed by FORC analysis. Under the gas atmosphere, saturation magnetization (Ms) and coercivity (Hc) of CoFe2O4 nanoparticles are obtained to be 41.5 emu/g and 34.1 Oe, respectively, whereas the nanoparticles synthesized without the gas atmosphere show Ms=33.8 emu/g and Hc=42.3 Oe. The magnetic hyperthermia of CoFe2O4 nanoparticles is measured by preparing concentrations of 1, 3, and 5 mg/ml of the nanoparticles under a magnetic field of 400 Oe and a frequency of 400 kHz. The results show that the highest magnetic hyperthermia is achieved at a concentration of 3 mg/ml, and the SLP value is 190.3 W/g. Overall, these findings suggest that the co-precipitation method is an effective approach for synthesizing biocompatible CoFe2O4 nanoparticles as confirmed by MTT analysis, having desirable properties for various applications, especially for magnetic hyperthermia.