Key Engineering Materials Vol. 1002

Abstract: The solid-state process of friction stirring is increasingly applied to weld or process Aluminum alloy 5052, which is essential to various applications, such as marine, aerospace, and automotive. Friction stirring typically induces microstructural changes and grain refinement, affecting the processed material's constitutive response. Applications involving friction-stir processed aluminum alloy 5052 might be subjected to impact and high-strain-rate loadings. Accordingly, this work investigates the effect of friction stir processing on the high-strain-rate behavior of aluminum alloy 5052. A Split Hopkinson Pressure Bar (SHPB) system is used to experimentally measure the high-strain-rate compressive response of friction-stir processed aluminum alloy 5052 at strain rates ranging between 2700 s^-1 to 5000 s^-1. A high-speed imaging system and the digital image correlation technique were used to measure full-field strain fields. Results showed that friction stir processed samples exhibit lower yield strength (less by 20.8% at strain rate 5000/s) than their unprocessed counterparts at the same strain rate. However, friction stir processed samples exhibited a higher hardening rate.

Abstract: Thermoplastic fiber-reinforced polymer (FRP) composites present a more sustainable alternative to their thermoset-based counterparts, owing to their potential for repair and recycling. Their capacity to meet sustainability standards, along with their ability to provide high stiffness and strength, has increased the use of thermoplastic FRP composites in load-bearing applications. Improving thermoplastic FRP's performance and sustainability is instrumentally dependent on optimizing their fabrication process parameters to minimize the energy consumed in their manufacturing without compromising their structural properties. Accordingly, this work utilizes experiments and artificial intelligence to model the relationship between interlaminar shear strength and the critical processing parameters in thermoplastic FRP laminate fabrication. These parameters are processing time, temperature, and pressure. Moreover, this work aims to utilize artificial intelligence to design the most sustainable processing sequence that reduces energy consumption without affecting FRP's structural integrity, represented by interlaminar shear strength. The artificial intelligence (AI) approach combines the use of an Adaptive Neuro Fuzzy Inference System (ANFIS) model and a Particle Swarm Optimization (PSO) algorithm in a Hybrid Intelligent-Assisted Model. Results demonstrated that increasing the processing time, pressure, and temperature beyond a certain threshold can deteriorate the fabricated laminates' performance. Moreover, results show that the energy consumption of the process can be reduced by reducing processing time without affecting the produced laminate's structural properties. A processing time of 6.44 minutes was determined by using a cascading Hybrid approach intelligent as the minimum time that can be used without affecting the interlaminar shear strength. Minimizing the processing time can reduce energy consumption by 34.56%.

Abstract: In this study, carbonate apatite [Ca_10-x(PO₄)_6-y(CO₃)_z(OH)_2-x-y-z, CHAp], a bone substitute material, was coated on roughened titanium through a sol-gel hydrothermal method. The sol-gel process was used to prepare calcium tartaric complexes, which were then subsequently hydrothermally treated on titanium in the presence of sodium hydroxide, and sodium hydrogen phosphate. The results showed that carbonate apatite, composed of nanosized fibers, was evenly deposited across the titanium surface. This coating resulted in a lower surface roughness (Ra) value of 1.31 μm compared to 3.98 μm for uncoated titanium. Additionally, the carbonate apatite coating decreased the contact angles of the titanium surface, thereby significantly enhancing cell attachment and migration compared to the uncoated surface. These results could be valuable for further evaluation of this coating in biomedical applications.

Abstract: Porous Titanium (Ti) is one of the leading biomedical materials with high biocompatibility, durability, high stability, and non-toxic to the human body. In this study, highly porous Ti have been fabricated by spark plasma sintering process using NaCl as a pore former (70% wt.), and then, NaCl was dissolved in water. All the samples were sintered at 625 °C and held there for 10 min under applied pressure ranging from 20 to 50 MPa with heating rate of 100 °C/min in vacuum. The results suggested that NaCl is a proficient porogen, the porosity of all samples was in the range of 66.95 - 68.8%. When the pressing pressure increased from 20 - 50 MPa, the porosity of the samples decreased but the size of the pores increased. The pore size concentrated in the range of 300 - 350 µm. This implies that the compression pressure plays a crucial role in influencing both the porosity and pore size of the titanium material produced using the SPS technique. The compressive strength is 18.42 - 25.23 MPa, and the elastic modulus is 0.35 - 1.05 GPa, which matches the strength and the modulus of elasticity of biological implants.

Abstract: In this research, smooth commercial Ti grade 2 corroded by ErCl₃.6H₂O under an electrochemical process with difference electrochemical current ranging from 0.5 – 4A, providing a rougher surface conducive to the adsorption on the Ti surface. A thin layer of TiO₂ nanotubes synthesized via the anodization method on microporous Ti surfaces for application in the biomedical field. The results reveal that the smooth titanium surface was completely corroded, resulting in the formation of a microporous structure, with a thin layer of TiO₂ successfully formed on the microporous titanium surfaces. The digital optical images obtained using digital microscope (VHX) showed that the micropore depth is around 41.94 - 55.83 µm. On the other hand, the SEM results revealed that the diameter of TiO₂ nanotubes ranged from 50 – 80 nm. The EDS and XRD techniques indicated that no impurities were present, and the TiO₂ phase was successfully formed. SEM images show positive results regarding the formation of a bone-like CaP mineral layer after 14 days of immersion in simulated body fluid (SBF), indicating suitability for biomedical applications.

Abstract: This article focused on investigating the influence of current density on the morphology and structure of silver nanoparticles (n-Ag) electrodeposited on anodized titanium substrates (denoted as TiO₂/Ti) on the surface. The TiO₂/Ti substrate served as the cathodic electrode placed in an electrolyte solution containing ionic [Ag(NH₃)₂]⁺ complex solution. The n-Ag/TiO₂/Ti samples were synthesized at current densities ranging from 0.2 A/dm² to 0.5 A/dm² for 20 seconds at room temperature. The study performed morphological and surface composition analysis of n-Ag/TiO₂/Ti using Field Emission Scanning Electron Microscopy (FESEM) and X-ray Diffraction (XRD) techniques. Additionally, the study assessed the electrochemical properties using the AutoLab system with Nova 2.1 software, based on Tafel curve measurements to compare the corrosion resistance of the samples before and after modification.

Abstract: To address the limitations of traditional drug delivery, CaTiO₃:Er³⁺ film (CTO:Er) is studied as a promising material for drug delivery systems. With regard to the excellent biocompatibility and physicochemical properties, CTO:Er prepared by a facile electrochemical anodizing process combined with a hydrothermal method has been used to fabricate new drug-releasing implants for localized drug delivery. This review discusses the development of CTO:Er applied in localized drug delivery systems, which uses nano drug curcumin for testing. Furthermore, with the special structure of the material, it meets the needs of drug absorption and delivery. Finally, the review concludes with the advances of CTO:Er for controlled drug delivery and corresponding prospects in the future.

Abstract: The scope of generation, accumulation and use of ash and slag waste of thermal power plants in different countries has been analyzed. The results of the study of the phase, mineralogical and chemical composition of ash and slag waste obtained with the dominance of solid and liquid fuel in the energy balance have been presented. It has been shown that the newly formed and previously accumulated ashes and slags of thermal power plants, with their correct and effective use, are a powerful source of expansion of raw materials in various industries. The existing methods of using ash and slag waste, which have been developed based on their mineral composition and the content of trace elements and impurities in them, have been considered. The most effective application of these wastes is in the construction industry, as well as when used as a raw material for obtaining compounds of rare metals, for example, vanadium.

Abstract: Ukraine has accumulated a large amount of industrial waste. The paper presents the results of the behavior of a mixture of waste dolomite and waste coal during heating. During the operation of enterprises a large amount of “waste” - small fractions of dolomite, which are in the dumps, has been accumulated. Waste is a valuable raw material for production of dolomite binders - lime and cement. Dolomite waste is used for comparison. Comparative analysis showed: energy consumption decreases. Reduction of energy costs indicates reduced fuel consumption for the process. The analysis of reduction of operational costs as a result of replacement of high-calorie fuel by coal preparation waste is carried out. Reduction of operational costs is shown when using dolomite waste instead of dolomite. The economic calculation of reduction of operational costs as a result of replacement of high-calorie fuel by coal preparation wastes is carried out.