Multidentate Cyclohexylphosphonic Acid as Corrosion Inhibitor for Structural Steel in 3.5% NaCl Solution: An Experimental and Computational Study

Protection of Metals and Physical Chemistry of Surfaces - The inhibition effect of cyclohexylphosphonic acid (CHPA) on the corrosion of structural steel (EN 10027) in 3.5% sodium chloride solution...     

Effect of the temperature of cerium nitrate–NaCl solution on corrosion inhibition of mild steel

In this study, the effect of temperature on corrosion inhibition is studied in the absence and presence of an optimal concentration of cerium nitrate (600 mg/L) as an inhibitor of mild steel in sodium chloride. Corrosion tests are carried out through electrochemical techniques such as impedance spectroscopy and d.c. polarization measurements. The surface morphology of the films is investigated by optical microscopy, white-light interferometry, and scanning electronic microscopy, coupled with energy-dispersive spectroscopy analysis for chemical composition. The results obtained show that the activation energy for the corrosion inhibition process to occur increases in the presence of a cerium nitrate inhibitor. However, the corrosion resistance of mild steel is somewhat lost upon increasing the solution temperature up to 55°C, which leads to more cracked films. The enthalpy and entropy values suggest a mixed mechanism of chemisorption and physisorption inhibition, with a major dominance of physisorption control.     

Impact of enzymatic treatment on wood surface free energy: contact angle analysis

The aim of this study was to investigate the effect of cellulase treatment on wood surface physicochemical characteristics. The cedar wood samples were treated by cellulase for 30 min at different concentrations: 0.2, 0.4, 0.6, 0.8, 1, and 1.2 mg/ml. Then the physicochemical properties (the wetting behavior and interfacial free energy) of the cedar samples surfaces were characterized by the sessile drop technique. The obtained results showed that the untreated cedar wood samples exhibited a hydrophobic character with a high water contact angle (θ_w = 71.9°) and a negative value of the interfacial free energy (?Giwi = ?59.3 mJ/m²). Thereafter, the wood hydrophobicity decreased continuously until it reached the hydrophilicity qualitatively (at the first concentration of cellulase (0.2 mg/ml)) and quantitatively (at 0.8 mg/ml of cellulase). The cedar wood surface treatment with cellulase also revealed a significant evolution of the acid-base parameters. Moreover, a linear relationship between the degree of hydrophobicity and the cellulase concentration has been found. This study clearly shows the impact that could have the produced enzyme by micro-organisms involved in wood biodegradation and especially their consequences on the physicochemical surface properties of the wooden materials.     

Bond graph modeling approach development for fuel cell PEMFC systems

This paper addresses the problem of bond graph methodology as a graphical approach for modeling fuel cell systems. The system consists of a Proton Exchange Membrane Fuel Cell (PEMFC) stack, an interleaved boost converter, battery pack connected via a buck converter.     

Improvement of surface conditions of 36 Cr Ni Mo 6 steel by ball burnishing process

Ball burnishing, a mechanical surface treatment, is becoming more popular as a finishing process. As results ball burnishing is noticed as a very simple way of surface mirror finishing and surface work-hardening. Applying the optimal input parameters, a pre-machined surface roughness Ra about of 3.01 μm can be finished to approximately 0.30 μm, whereas an initial hardness HRA about 66.35 can be increased to 71.33. A metallographic observation and some measurement of micro-hardness show that the depth of penetration strengthened by plastic surface deformation (PSD) reaches 100 μm. Results analysis show that burnishing force, burnishing ball radius and number of ball burnishing tool passes have the most significant effects on both surface responses (Ra and HRA). For the generating of high surface qualities and strengthening superficial layers, an alternative to chip-forming process and heat treatments can be given by ball PSD process.