Role of Vanadium Additions on the Corrosion Mitigation of Ti-6Al-xV Alloy in Simulated Body Fluid

Developing Improved Corrosion-Resistant AA5083-BN/WC Composites for Tribological Applications

In this study, corrosion-resistant AA5083-BN/WC composites were developed for tribological applications through adequate control of the reinforcement content (WC and BN) in the matrix (AA5083 alloy). The effects of 6% and 12% tungsten carbide (WC) as well as 6% and 12% boron nitride (BN) additions on the corrosion behavior of AA5083 aluminum composite in 3.5% NaCl solution were carried out. Electrochemical techniques such as cyclic potentiodynamic polarization (CPP), changes in the chronoamperometric current with time (CCT), and electrochemical impedance spectroscopy (EIS) were utilized. The polarization results showed that the addition of 6% WC to the AA5083 alloy matrix improved its resistance to corrosion (R_P). Rp exhibited an additional increase by adding 12% WC to the matrix. The values of R_P were observed to increase for the AA5083 composite when adding 6% BN, and the highest R_P values were recorded for the composite that contains 12% BN. The results obtained by the CPP method were confirmed by CCT and EIS measurements, where the presence of WC and BN protected the developed AA5083- BN/WC composites against corrosion. The corrosion resistance revealed an additional improvement with an increase in WC and BN content from 6% to 12%. The results also confirm that pitting corrosion decreased in the presence of WC and BN in the fabricated composites.

Influence of Tantalum Addition on the Corrosion Passivation of Titanium-Zirconium Alloy in Simulated Body Fluid

Ti-15%Zr alloy and Ti-15%Zr-2%Ta alloy were fabricated to be used in biomedical applications. The corrosion of these two alloys after being immersed in simulated body fluid for 1 h and 72 h was investigated. Different electrochemical methods, including polarization, impedance, and chronoamperometric current with time at 400 mV were employed. Also, the surface morphology and the compositions of its formed film were reported by the use of scanning electron microscope and energy dispersive X-ray. Based on the collected results, the presence of 2%Ta in the Ti-Zr alloy passivated its corrosion by minimizing its corrosion rate. The polarization curves revealed that adding Ta within the alloy increases the corrosion resistance as was confirmed by the impedance spectroscopy and current time data. The change of current versus time proved that the addition of Ta reduces the absolute current even at high anodic potential, 400 mV. The results of both electrochemical and spectroscopic methods indicated that pitting corrosion does not occur for both Ti-Zr and Ti-Zr-Ta alloys, even after their immersion in SBF solutions for 72 h.

Enhancement of Surface and Interface Properties of Low Carbon Steel by Hybrid ZnO and NiO Nanoparticles Reinforced Tin Coating

Tin matrix nanocomposite coatings containing ZnO and NiO nanoparticles, both individually and combined, were deposited on low carbon steel substrates. The aim was to investigate the effect of reinforcement of nanoparticles on microstructural morphology and thickness of tin coatings, modification in the interfacial layer between coating and substrate, and the corrosion resistance of low carbon steel substrate. Optical and scanning electron microscopy were employed for microstructural observation, while potentiostat-galvanostat was utilized for electrochemical investigation. It was found that the tin nanocomposite coatings with nanoparticles significantly modified the coating thickness, intermetallic layer thickness, and surface corrosion resistance. Coatings through the direct tinning process are considered to be a simple and low-cost route for protecting metallic materials from corrosion, and the presence of ZnO and NiO nanoparticles in tin coatings further increases the corrosion resistance of low carbon steels.

Influence of Zirconium on the Corrosion Passivation of Titanium in Simulated Body Fluid

Pure Ti and 85%Ti-15%Zr alloy were sintered in a heat induction high frequency furnace. The corrosion behaviour of Ti and 85%Ti-15%Zr in simulated body fluid (SBF) was studied. The work was achieved using different techniques as the cyclic polarization (PCP), the impedance spectroscopy (EIS), and the change of the potentiostatic current with time (PCT) experiments. The morphology of the surfaces of Ti and Ti-Zr after being corroded in SBF for 72 were investigated by a scanning electron microscope (SEM) and the analysis for the layer formed on that surface was collected via energy dispersive X-ray (EDX). Results depicted that the 15% Zr present within Ti decreases the corrosion via increasing Ti corrosion resistance and minimizing its measured corrosion rate. PCP data proved that the addition of Zr reduced all anodic, cathodic and corrosion currents. EIS results confirmed that Zr has a positive impact on the reduction of corrosion resistance. PCT, SEM, and EDX examinations displayed that both Ti and Ti-Zr alloy don’t show pitting corrosion even after 72 h exposure to SBF.

Slurry Erosion-Corrosion Characteristics of As-Built Ti-6Al-4V Manufactured by Selective Laser Melting

Erosion and erosion–corrosion tests of as-built Ti-6Al-4V manufactured by Selective Laser Melting were investigated using slurries composed of SiO₂ sand particles and either tap water (pure water) or 3.5% NaCl solution (artificial seawater). The microhardness value of selective laser melting (SLM)ed Ti-6Al-4V alloy increased as the impact angle increased. The synergistic effect of corrosion and erosion in seawater is always higher than erosion in pure water at all impact angles. The seawater environment caused the dissolution of vanadium oxide V₂O₅ on the surface of SLMed Ti-6Al-4V alloy due to the presence of Cl⁻ ions in the seawater. These findings show lower microhardness values and high mass losses under the erosion–corrosion test compared to those under the erosion test at all impact angles.