Effects of minor additions of ruthenium on the passivation of duplex stainless-steel corrosion in concentrated hydrochloric acid solutions

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.

Impediment of Iron Corrosion by N,N′-Bis[2-hydroxynaphthylidene]amino]oxamide in 3.5% NaCl Solution

Hydrazone [N,N′-bis[2-hydroxynaphthylidene]amino]oxamide] derived from the condensation of ethanedihydrazide with 2-hydroxynaphthalene-1-carbaldehyde was synthesized and assessed on the basis of elemental analysis (CHN) and spectral (IR, mass, 13C/1H NMR and UV-Vis) measurements. The influence of N,N-bis([2-hydroxynaphthylidene]amino)oxamide (HAO) in terms of the inhibition of iron corrosion in concentrated sodium chloride solution (3.5 wt.% NaCl) after various exposure periods was assessed. Numerous electrochemical and spectroscopic assessment techniques were performed. Cyclic potentiodynamic polarization experiments indicated that the presence of HAO and its increased concentration decreased the corrosion of iron in NaCl solution by decreasing the corrosion values, anodic and cathodic currents, and corrosion rate. The electrochemical impedance spectroscopy results showed that HAO molecules greatly increased the corrosion resistance. The chronoamperometric experiments performed at −475 mV (Ag/AgCl) revealed that the HAO molecules decreased the absolute currents and reduced the probability of the occurrence of pitting corrosion. The effect of HAO on the inhibition of iron corrosion was also confirmed through scanning electron microscopy micrographs and energy-dispersive X-ray profile analyses, which proved that the surface of the iron sample exposed to chloride solution alone was pitted, while the presence of HAO molecules reduced the severity of the pitting corrosion. The results confirmed that the presence of HAO molecules inhibits the corrosion of iron and this impact increased when the exposure time was increased to 48 h.