The electrochemical and mechanical behavior of phosphated and industrially drawn high-carbon pearlitic steel wire

This research investigates the electrochemical and mechanical behavior of phosphated and industrially drawn high-carbon pearlitic steel wire produced by the national company Trefisoud El Eulma, focusing on how progressive drawing deformation influences the steel’s structural, mechanical, and electrochemical characteristics as well as the performance of the coated surface at strain levels ε = 0, 0.68, 1.01, and 2.05. A combination of SEM and EBSD analyses revealed continuous pearlite refinement, reduction in interlamellar spacing, and development of a <110> fiber texture, while XRD quantification of dislocations confirmed a significant increase in defect density with deformation. Microhardness, nanoindentation, and wear tests indicated progressive strengthening and enhanced tribological properties, whereas electrochemical analyses (EIS and polarization) performed in simulated concrete pore solutions containing chlorides and sulfates demonstrated that deformation affects passivity, with sulfate ions stabilizing the passive film and chloride ions promoting localized attack. The zinc phosphate coating, characterized by XRD, SEM, scratch adhesion, and electrochemical testing, initially provided effective protection but exhibited decreasing adhesion and corrosion resistance with higher strain levels. Overall, the results establish a direct link between deformation, dislocation density, interlamellar spacing, and coating performance, offering valuable guidance for optimizing wire drawing and surface treatment processes to improve the durability of high-strength steels used in prestressed concrete applications.

Ni-assisted synthesis and densification processes of TiC based materials

This study investigates the synthesis and densification of titanium carbide based materials using two distinct approaches. The first incorporates mechanically activated NiO/Al powder into a Ti+C mixture, while the second directly adds nickel powder to the Ti+C mixture. Self-propagating high-temperature synthesis and hot pressing were employed for material synthesis. To enhance densification and microstructural properties, hot-pressed samples underwent heat treatment at 1450°C. Optimizing the NiO/Al milling parameters led to the most refined mixture using a ball-to-powder ratio of 42:1, a milling speed of 200 rpm, and a duration of 1 hour. The introduction of mechanically activated NiO/Al into the Ti-C system significantly accelerated the combustion synthesis process, leading to the formation of TiC, hot Ni, and Al₂O₃. X-ray diffraction analysis confirmed that the dominant phases formed during hot pressing were TiC, nickel, and alumina, alongside intermetallic phases such as Ti₂Ni and NiTi. Microstructural analysis showed that TiC without additives had high porosity, while NiO/Al incorporation resulted in a denser structure with smaller TiC particles. For Ti-C-Ni samples, XRD analysis confirmed the formation of TiC along with intermetallic phases such as Ti₂Ni, TiNi, and Ni₃C across both synthesis routes. Comparative analysis demonstrated that TiC synthesized with the mechanically activated NiO/Al mixture exhibited superior performance compared to TiC obtained through direct nickel addition. Moreover, Electron Probe Microanalysis validated the XRD findings for hot-pressed samples, while Scanning Electron Microscopy highlighted nickel's presence at TiC grain boundaries. The tribological evaluation further indicated that samples with higher binder content exhibited increased friction coefficients, emphasizing the correlation between binder concentration and wear resistance.