To analyze the spinodal decomposition in Zr-Nb-Ti alloys, a phase field method, based on the Cahn-Hilliard equation, was employed to examine the impact of titanium concentration and aging temperatures (ranging from 800 K to 925 K) on the alloys' spinodal structure over 1000 minutes. Analysis revealed spinodal decomposition in Zr-40Nb-20Ti, Zr-40Nb-25Ti, and Zr-33Nb-29Ti alloys aged at 900 K, resulting in the formation of Ti-rich and Ti-poor phases. Following aging at 900 K, the early stages of spinodal phase evolution in Zr-40Nb-20Ti, Zr-40Nb-25Ti, and Zr-33Nb-29Ti alloys exhibited distinct morphologies: an interconnected, non-oriented maze-like form; a discrete, droplet-like shape; and a clustered, sheet-like structure, respectively. A surge in Ti concentration in Zr-Nb-Ti alloys resulted in an expansion of the concentration modulation's wavelength, but a contraction of its amplitude. The aging temperature played a pivotal role in the spinodal decomposition observed in the Zr-Nb-Ti alloy system. Elevated aging temperatures in the Zr-40Nb-25Ti alloy led to a shift in the Zr-rich phase's shape, progressing from an intricate, interlinked, and non-oriented maze-like form to a discrete droplet-like structure. Simultaneously, the concentration modulation wavelength increased rapidly to a stable state, although the modulation's amplitude decreased within the alloy. Spinodal decomposition failed to manifest in the Zr-40Nb-25Ti alloy when the aging temperature ascended to 925 Kelvin.
Employing a 70% ethanol solution and microwave-assisted extraction, glucosinolates-rich extracts were produced from various Brassicaceae sources, including broccoli, cabbage, black radish, rapeseed, and cauliflower, and were subsequently evaluated for in vitro antioxidant and anticorrosion activity against steel. The DPPH method and Folin-Ciocalteu assay demonstrated excellent antioxidant capabilities for all tested extracts, indicating a range of 954 to 2203 percent DPPH remaining and total phenolic content in the range of 1008 to 1713 mg GAE per liter. Using electrochemical techniques in a 0.5 M H₂SO₄ solution, it was found that the extracts act as mixed-type inhibitors, showcasing a correlation between concentration and corrosion inhibition. Extracts from broccoli, cauliflower, and black radish showed impressive inhibition efficiencies, between 92.05% and 98.33% at concentrated levels. The weight loss experiments' findings show that inhibition efficiency inversely correlates with elevated temperature and extended exposure times. Detailed examination of the apparent activation energies, enthalpies, and entropies, concerning the dissolution process, led to the development and discussion of an inhibition mechanism. A surface examination employing SEM and EDX technologies shows that extract components bind to the steel surface, creating a shielding barrier layer. Furthermore, the FT-IR spectra unequivocally show the formation of bonds linking functional groups to the steel substrate.
Employing experimental and numerical methodologies, the paper explores the resultant damage of thick steel plates exposed to localized blast loading. Three steel plates, each 17 mm thick, were impacted by a localized trinitrotoluene (TNT) explosion, and their affected regions were subsequently scanned with a scanning electron microscope (SEM). Simulation of the steel plate's damage was undertaken using ANSYS LS-DYNA software. The interplay between empirical results and numerical simulations yielded insights into TNT's impact on steel plates, unveiling the damage patterns, confirming the accuracy of the numerical model, and establishing criteria for identifying the different types of steel plate damage. A dynamic relationship exists between the explosive charge and the steel plate's damage mode. Primarily, the crater's dimension on the steel plate's surface correlates with the contact area between the explosive and the steel plate. Cracks propagating through the steel plate manifest as a quasi-cleavage fracture, whereas craters and perforations arise from ductile fracture mechanisms. The breakdown of steel plate damage includes three categories. Numerical simulation results, though featuring minor errors, possess considerable reliability and can function as an auxiliary tool to complement experimental work. A new measure is devised to forecast the damage pattern of steel plates exposed to contact explosions.
In wastewater, the hazardous radionuclides cesium (Cs) and strontium (Sr), which arise from nuclear fission, may be accidentally introduced. A batch-mode experiment investigated the adsorption capacity of thermally treated natural zeolite (NZ) sourced from Macicasu, Romania, in removing Cs+ and Sr2+ ions from aqueous solutions. Varied amounts (0.5 g, 1 g, and 2 g) of zeolite samples with particle sizes categorized as 0.5-1.25 mm (NZ1) and 0.1-0.5 mm (NZ2) were contacted with 50 mL of working solutions containing Cs+ and Sr2+ ions, at initial concentrations of 10, 50, and 100 mg/L, respectively, for a period of 180 minutes. The concentration of Cs in aqueous solutions was quantitatively assessed using inductively coupled plasma mass spectrometry (ICP-MS), while the strontium (Sr) concentration was determined via inductively coupled plasma optical emission spectrometry (ICP-OES). Cs+ removal effectiveness exhibited a fluctuation between 628% and 993%, in stark contrast to Sr2+, whose removal efficiency spanned from 513% to 945%, influenced by the initial concentrations, contact time, the adsorbent's mass and particle dimensions. The analysis of Cs+ and Sr2+ sorption employed nonlinear Langmuir and Freundlich isotherm models, coupled with pseudo-first-order and pseudo-second-order kinetic models. The results indicated that the PSO kinetic model accurately represents the rate at which cesium and strontium ions bind to thermally treated natural zeolite. Strong coordinate bonds formed with the aluminosilicate zeolite framework are responsible for the dominant role of chemisorption in retaining both Cs+ and Sr2+ ions.
A comprehensive examination of metallographic characteristics and tensile, impact, and fatigue crack growth performance of 17H1S main gas pipeline steel is presented in this work, covering both the as-received state and the condition after extended operation. The LTO steel's microstructure exhibited a substantial amount of non-metallic inclusions arranged in chains oriented along the pipe rolling axis. Near the pipe's inner surface, in the lower portion, the steel exhibited the lowest values for both elongation at break and impact toughness. Tests using the FCG method, conducted on degraded 17H1S steel samples at a stress ratio of R = 0.1, showed no noticeable difference in growth rate compared to samples in the AR state. The stress ratio R = 0.5 during the tests exhibited a more pronounced effect on degradation. Concerning the LTO steel situated close to the inner surface of the lower pipe section, the da/dN-K diagram's Paris law region was superior to those of the AR-state steel and the LTO steel located in the upper section of the pipe. Non-metallic inclusions, exhibiting a substantial number of delaminations, were evident in the matrix, as observed fractographically. It was recognized that their presence played a part in making the steel more fragile, particularly within the inner area of the pipe's lower part.
This research project sought to fabricate a unique bainitic steel capable of achieving a high degree of refinement (nano- or submicron scale) while maintaining enhanced thermal stability at elevated temperatures. Drug Screening The enhanced in-use property, thermal stability, demonstrated by the material, contrasted favorably with the limited carbide precipitation observed in nanocrystalline bainitic steels. The expected low martensite start temperature, bainitic hardenability, and thermal stability are governed by the assumed criteria. Presented here are the novel steel design process, along with its complete characteristics, including continuous cooling transformation and the time-temperature-transformation diagrams determined through dilatometry. In addition, the influence of bainite transformation temperature was also examined in relation to the level of structural refinement and the size of austenite blocks. buy MSU-42011 It was examined if a nanoscale bainitic structure could be realized in medium-carbon steel samples. Lastly, the performance of the applied strategy for boosting thermal stability under elevated temperatures was analyzed in detail.
In medical surgical implant applications, Ti6Al4V titanium alloys are advantageous due to their high specific strength and the favorable biological compatibility they exhibit with the human body. Ti6Al4V titanium alloys are, unfortunately, prone to corrosion in the human environment, thus diminishing the longevity of implants and having an impact on human health. In this research, the technique of hollow cathode plasma source nitriding (HCPSN) was implemented to produce nitrided layers on the surfaces of Ti6Al4V titanium alloy components, resulting in improved corrosion resistance. Ti6Al4V titanium alloys experienced nitriding in an ammonia atmosphere maintained at 510 degrees Celsius for 0, 1, 2, and 4 hours. High-resolution transmission electron microscopy, atomic force microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were utilized to characterize the microstructure and phase composition of the Ti-N nitriding layer. Analysis revealed that the modified layer is comprised of TiN, Ti2N, and the -Ti(N) phase. To ascertain the corrosion characteristics of diverse phases, samples nitrided for 4 hours were mechanically ground and polished to expose the varied surfaces of Ti2N and -Ti (N) phases. Noninvasive biomarker Corrosion resistance of Ti-N nitrided layers in a human-like environment was investigated via potentiodynamic polarization and electrochemical impedance techniques using Hank's solution. A discussion of the correlation between corrosion resistance and the microstructural characteristics of the Ti-N nitrided layer was undertaken. In the medical sphere, the Ti6Al4V titanium alloy, strengthened by the corrosion-resistant Ti-N nitriding layer, has an expanded potential.