Corrosion Rate Of Nickel Research Articles

Microstructural investigations of pure nickel exposed to KCl induced high temperature corrosion

Oxidation of 99·99% pure nickel was studied with and without 0·10 mg cm−2 KCl(s) in an environment containing 5 vol.-%O2, 40 vol.-%H2O and 55 vol.-%N2 at 600°C for up to 168 h. Oxide microstructure was investigated by X-ray diffraction (XRD), focused ion beam (FIB), broad ion beam (BIB) and SEM/EDX. Oxidised nickel shows an approximately parabolic oxide growth rate. The oxide scale is dense with some pores at the oxide/metal interface. Adding small amounts of KCl does not result in a faster corrosion rate of nickel. However, the surface morphology changes and small oxide crusts were observed in the vicinity of former KCl particles. This is proposed to be the result of a NiCl2–KCl eutectic on top of the oxide scale formed above 514°C. The oxide scale formed in the presence of KCl contains more and differently distributed voids than the scale formed without KCl.

Corrosion behavior of Zn and Ni coated carbon steels in 3% NaCl

Corrosion behavior of electrolytic coated carbon steel in 3% NaCl solution was investigated using potentiodynamic polarization, lineer polarization resistance, chronoamperometry, open circuit potential as a function of time and impedance (EIS) measurements. Zn and Ni coated carbon steel surfaces immersed into 3% NaCl solution during 1, 5 and 10 days were characterized using scanning electron microscope (SEM). According to the experimental results, nickel coated carbon steel corrosion resistance was higher than that of Zn coating. Accordingly, the corrosion rate of nickel coated carbon steel decreased by 89.6% compared to the zinc coating.

Corrosion-Electrochemical Behavior of Nickel in Ozonized Sulfuric Acid Solutions

Ozonization of sulfuric acid solutions increases the corrosion rate of nickel, in the mean, by an order of magnitude but, at the same time, decreases its hydrogenation. Cathodic processes are responsible for the active part of hydrogen ions in ozone reduction with the formation of hydroxyl ions and hydrogen peroxide in the near-electrode layer.

Effect of Oxygen on the Electrochemical and Corrosion Behavior of Rotating Nickel Disks in H2SO4

Abstract The electrochemical and corrosion behavior of nickel in deoxygenated and oxygenated H2SO4 (pH = 0.3) have been studied by the rotating disk technique. Some preliminary corrosion inhibition results of nickel by benzotriazole(BTA) have also been obtained. In the absence of oxygen, three distinct Tafel regions have been observed for the anodic dissolution of nickel with corresponding Tafel slopes of 0.065, 0.040, and 0.115 V/dec. On the other hand, for nickel in solutions containing benzotriazole, an anodic Tafel region of about three decades with a slope of 0.040 V/dec was obtained. The corrosion potential and corrosion rate of nickel in H2SO4 was dependent on the dissolved oxygen content and the hydrodynamic conditions. The corrosion of nickel is controlled by the rate of mass transfer of oxygen above disk rotation rates of 500 rpm and above partial pressures of oxygen of 0.1 atmosphere. For example, the corrosion rates were 0.19 and 7.3 mA/cm2 at 500 rpm and 0.1 atmosphere oxygen, and 4500 rpm an...

空気を含む水溶液中におけるニッケルの自己不働態化

The corrosion rate of nickel was measured in aerated sulfate solutions of various pH. An abrupt change of corrosion rate was found at aboult pH 5. In acidic region, the corrosion rate was nearly equal to the diffusion rate of dissolved oxygen and the spontaneous potential was less noble than the Flade potential. In alkaline solution, on the other hand, the corrosion rate was undetectablly small and the spontaneous potential was in the passive region. The polarization curve of nickel in acidic solution (pH=3.77) showed that the maximum dissolution current of iMmax in the active state, which can be measured in the solution saturated with pure nitrogen gas, was larger than the reduction current of dissolved oxygen iO. While, in neutral solution (pH=7.53), iMmax was smaller than iO. The critical state of iMmax=iO was found to be at about pH=5. It could be explained from the electrochemical standpoint that nickel is passivated by the reduction current of dissolved oxygen (O2+2H++4e→2OH−) only when |iMmax|<|iO|.