Evolution of Surface Integrity Characteristics and Mechanical Behavior of Diamond Burnished and Turned AISI 304 Steel Specimens After Prolonged Exposure to Natural Seawater

Coatings, Journal Year: 2025, Volume and Issue: 15(1), P. 31 - 31

Published: Jan. 1, 2025

This article presents results on the evolution of surface integrity, microstructure, mechanical characteristics, fatigue strength, and wear behavior AISI 304 steel specimens after prolonged exposure (up to 746 days) a natural seawater environment, specifically near port Varna, Bulgaria. The samples, having different shapes sizes according respective tests, were divided into two main groups based finishing process: fine turning (FT) diamond burnishing (DB). Additionally, FT polished meet standard requirements. Some cylindrical samples from both heat-treated dissolve car-bides. No significant improvement in corrosion resistance (FT DB) was observed compared with untreated days immersion seawater. Overall, all types DB showed less mass loss (indicating higher resistance), static greater plasticity, than corresponding specimens. Notably, pitting specimens, as well trac-es intergranular some hardening effects have complex impact activity. increases dislocation density internal energy subsurface layers intensify nucleation centers layers; however, refined fibrous structure reduction roughness slow down development corrosion. Therefore, implementation smoothing process will re-duce energy, hence lead further resistance.

Language: Английский

Extraction and Separation of Ytterbium and Nickel from Heavy Metal Solutions Containing Manganese and Calcium Impurities

Minerals, Journal Year: 2025, Volume and Issue: 15(4), P. 414 - 414

Published: April 14, 2025

This study systematically investigated the extraction and separation of ytterbium (Yb) nickel (Ni) from manganese (Mn)- calcium (Ca)-containing heavy metal solutions using 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (HEHEHP) in nitric media. Results demonstrated that logarithms distribution ratios for Yb, Ni, Mn, Ca exhibited positive correlations with both solution pH logarithm extractant concentration, consistent theoretical models. Elevated initial concentrations reduced all elements, indicating inhibition. Ytterbium back-extraction efficiency increased proportionally hydrochloric concentration number stages. Optimization key parameters established predictive equilibrium relationships: Yb/Ni Mn/Ca coefficients decreasing acidity whereas Mn/Ni Ca/Ni rose under higher conditions. Infrared spectroscopy confirmed HEHEHP-Yb complexation mechanisms, stability retained through multiple reuse cycles. Optimized cascade processing (3 stages, 3 washing 4 stages) achieved >99.9% purity Yb Ni. validated methodology provides a robust technical framework waste treatment high-value element recovery.

Language: Английский