The inhibition effect of the molybdate on hydrogen permeation of 2205 duplex stainless steel

The inhibition effect of molybdate on stress corrosion cracking (SCC) was investigated by many researchers, but few considered the molybdate effect on hydrogen permeation and the relationship between SCC and hydrogen permeation. This paper presents the effect of molybdate on SCC susceptibility and hydrogen permeation through the 2205 super duplex stainless steel in a sulfuric acid solution. An addition of molybdate has an interesting influence. It decreases the SCC susceptibility. With its increasing concentration, the inhibition effect on the hydrogen permeation remains steady. Attempts were made to understand this behaviour based on the role of molybdate in hydrogen permeation and pitting characteristics of the 2205 stainless steel in a sulfuric acid solution.

Section: Pit Observationmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

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Effect of molybdate on the stress corrosion cracking of 2205 duplex stainless steel in sulfuric acid solution

Yi¹,

Xing²,

Qi³

et al. 2019

“…[1][2][3] Using corrosion inhibitors is one of the most efficient and economical methods for the protection of metals and their alloys against corrosion, especially in acidic solutions. [4][5][6] Organic compounds with p electrons and heteroatoms such as O, N, S proved to be the most effective corrosion inhibitors. [7][8][9][10] The electrostatic physisorption or chemisorption ascribed to the transformation of electrons from inhibitors to the metal surface are considered to be the reasons why inhibitors can retard the corrosion behaviour.…”

Section: Introductionmentioning

confidence: 99%

Benzimidazole and its derivatives as corrosion inhibitors for mild steel in hydrochloric acid

Li¹,

Wang²,

He³

et al. 2018

Using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS), the inhibition ability of benzimidazole (BI), 2-methylthiobenzimidazole (2-MBI) and 2-chloromethylbenzimidazole (2-CBI) for mild steel in an HCl solution (1 mol L-1) was investigated. With an increase in the concentration, 2-MBI showed the highest inhibition efficiency (IE) at 1.24×10-3 mol L-1 , while the IE of BI and 2-CBI increased continuously within the investigated concentration range. The IE increased in the order of BI < 2-MBI < 2-CBI, which was further confirmed by the morphologies of the mild-steel surfaces after their immersion in 1M HCl with or without different inhibitors. Fitted adsorption isotherm curves suggested that the adsorption of the three inhibitors onto the mild steel in 1M HCl follow the Langmuir adsorption isotherm. Considering the effects of the temperature on the adsorption behaviour of the inhibitors, the apparent activation energy (Ea) of the mild-steel corrosion in the HCl solution with BI, 2-MBI and 2-CBI was calculated as (42.00, 48.28 and 67.93) kJ mol-1 , respectively.

“…[1][2][3] Thus, the corrosion problems of the materials under deep-ocean conditions must be considered. The environment of the deep ocean is a complicated system, including hydrostatic pressure, differently dissolved oxygen (DO), all kinds of salts, water velocity and suspended silt.…”

Section: Introductionmentioning

confidence: 99%

EIS and SKP study on improvement of the protection performance of an alkyd-varnish coating modified with air-plasma treatment on Q235 steel

Zheng¹,

Qu²,

Wang³

2017

Electrochemical impedance spectroscopy (EIS) and scanning Kelvin probe (SKP) were used to study the failure of the coating modified with air-plasma treatment in 3.5 % mass fraction of NaCl. The results show that the failure process can be divided into three stages including water penetration, accumulation of corrosion products at the location of a defect, water penetration of the entire coating and coating failure. The EIS results show that the plasma-treated samples exhibit an additional electrical double-layer capacitor that delays the coating failure during the second stage. The potential of the non-plasma-treated samples decrease faster than that of the plasma-treated samples according to the SKP study. As the transition layer, air plasma delays the coating failure due to the chemical bond between the metal substrate and the coating. Keywords: air-plasma treatment, electrochemical impedance spectroscopy, scanning Kelvin probe, coating failure, hydrostatic pressure Elektrokemijsko impedan~no spektroskopijo (angl. EIS) in vrsti~no Kelvinovo sondo (SKP) smo uporabili za preu~evanje po{kodb na prevleki, modificirani s plazmo, v 3,5 mas. % raztopini NaCl. Rezultati ka`ejo, da se nastajanje po{kodb lahko razdeli na tri faze, vklju~no s penetracijo vode: na akumulacijo korozijskih produktov na mestu napake, na prodiranje vode v dele celotne prevleke in na odpoved prevleke. Rezultati EIS ka`ejo, da imajo vzorci, obdelani v plazmi, dodaten elektri~ni dvoslojni kondenzator, ki v drugi fazi upo~asni po{kodbo prevleke (premaza). SKP-analize so pokazale, da se potencial plazemsko neobdelanih vzorcev zmanj{uje hitreje kot tistih vzorcev, ki so bili obdelani s plazmo. Kot prehodna plast, obdelava z zra~no plazmo upo~asni po{kodbo premaza zaradi kemijske vezi med kovinskim substratom in prevleko. Klju~ne besede: obdelava s plazmo, elektrokemijska impedan~na spektroskopija, skeniranje s sondo Kelvin, odpoved prevleke, hidrostati~ni tlak