Optical Microscopy Studies of Anodic Dissolution of Iron In Sulfuric and Hydrochloric Acid Solutions

CORROSION ◽  
1968 ◽  
Vol 24 (4) ◽  
pp. 90-95 ◽  
Author(s):  
L FELLONI ◽  
G. P. CAMMAROTA
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Grain Orientation ◽  
Competitive Adsorption ◽  
Armco Iron ◽  
Water Molecules ◽  
Dissolution Mechanism ◽  
Acid Solutions ◽  
Hydrochloric Acid Solutions ◽  
Sulfuric Acid Solutions

Abstract Microscopical observation was made during and after intensiostatic polarization of Armco iron electrodes. A correlation between etching degree and grain orientation was evident in sulfuric acid solutions. In hydrochloric acid solutions a smoothing at the inside of the grains, independently of their orientation and preferential corrosion at the boundaries occurred. It is suggested that in sulfuric acid the dissolution mechanism involving anion participation may be effective, while in hydrochloric solutions a competitive adsorption very probably takes place between Cl− and OH− or water molecules.

Inhibitory effect of Pistacia khinjuk aerial part extract for carbon steel corrosion in sulfuric acid and hydrochloric acid solutions

2019 ◽  
Vol 74 (6) ◽  
pp. 1799-1815 ◽  
Author(s):  
Nasrin Soltani ◽  
Nahid Tavakkoli ◽  
Abdolmohammad Attaran ◽  
Batoul Karimi ◽  
Maryam Khayatkashani
Keyword(s):  
Sulfuric Acid ◽  
Carbon Steel ◽  
Hydrochloric Acid ◽  
Aerial Part ◽  
Steel Corrosion ◽  
Inhibitory Effect ◽  
Acid Solutions ◽  
Hydrochloric Acid Solutions ◽  
Pistacia Khinjuk

The excess acidity method. The basicities, and rates and mechanisms of enolization, of some acetophenones and acetone, in moderately concentrated sulfuric acid

1979 ◽  
Vol 57 (22) ◽  
pp. 2952-2959 ◽  
Author(s):  
Robin A. Cox ◽  
Clinton R. Smith ◽  
Keith Yates
Keyword(s):  
Sulfuric Acid ◽  
Function Method ◽  
Water Molecules ◽  
Acid Solutions ◽  
Linear Free Energy ◽  
Rate Determining Step ◽  
Energy Relationships ◽  
Concentrated Sulfuric Acid ◽  
Sulfuric Acid Solutions ◽  
Medium Acidity

The X-function method has been used to evaluate the basicities of six nuclear-substituted acetophenones and acetone, using a combination of new measurements and literature data; the protonation [Formula: see text] of acetone was found to be −5.37. The same method, which involves the excess medium acidity, when used to analyze the enolization rate constants obtained from the measured bromination rates, shows that most of the acetophenones enolize by an A-2 process involving two water molecules in the rate-determining step. Observed linear free energy relationships for the basicities and the enolization rates imply a relatively early transition state for the enolization. Acetone was found to enolize by a similar mechanism in sulfuric acid solutions more dilute than 81% w/w, but at higher acidities bisulfate ion was the preferred base. The mechanistic behaviour of 4-nitroacetophenone was found to be different, not A-2 but either A-1 or A-SE2.

scholarly journals Corrosion Properties of Cr27Fe24Co18Ni26Nb5 Alloy in 1 N Sulfuric Acid and 1 N Hydrochloric Acid Solutions

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5924
Author(s):  
Chun-Huei Tsau ◽  
Po-Min Chen
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
High Entropy Alloy ◽  
Acid Solutions ◽  
Corrosion Properties ◽  
High Entropy ◽  
Hydrochloric Acid Solutions ◽  
Fcc Phase

The composition of the Cr27Fe24Co18Ni26Nb5 high-entropy alloy was selected from the FCC phase in a CrFeCoNiNb alloy. The alloy was melted in an argon atmosphere arc-furnace, followed by annealing in an air furnace. The dendrites of the alloy were in the FCC phase, and the eutectic interdendrites of the alloy comprised HCP and FCC phases. The microstructures and hardness of this alloy were examined; the results indicated that this alloy was very stable. This microstructure and hardness of the alloy almost remained the same after annealing at 1000 °C for 24 h. The polarization behaviors of Cr27Fe24Co18Ni26Nb5 alloy in 1 N sulfuric acid and 1 N hydrochloric acid solutions were measured. Both the corrosion potential and the corrosion current density of the Cr27Fe24Co18Ni26Nb5 alloy increased with increasing test temperatures. The activation energies of the Cr27Fe24Co18Ni26Nb5 alloy in these two solutions were also calculated.

Corrosion Resistance of Electrodeposited RE-Ni-W-P-SiC-PTFE Composite Coatings

2008 ◽  
Vol 41-42 ◽  
pp. 349-355
Author(s):  
Xiao Yun Zhu ◽  
Zhong Cheng Guo ◽  
Xian Wan Yang
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Composite Coatings ◽  
Acid Solutions ◽  
Anode Polarization ◽  
Ptfe Composite ◽  
Corrosion Rates ◽  
Hydrochloric Acid Solutions

Corrosion rates and anode polarization curves of RE-Ni-W-P-SiC-PTFE composite coatings in various concentrations of sulfuric acid and hydrochloric acid solutions have been studied. Results show that corrosion law of the RE-Ni-W-P-PTFE-SiC composite coatings in various concentrations of sulfuric acid solutions is identical. The corrosion rates of the composite coatings are increased with increasing sulfuric acid concentration while the corrosion rates are decreased with increasing concentration of hydrochloric acid. Anode polarization curves of RE-Ni-W-P-SiC-PTFE composite coatings in various concentrations of sulfuric acid and hydrochloric acid solutions have showed that anode polarization electric current density of the composites at 200°C or 500°C heat treatment was below that at other heat treatment, it is clear that the composite coatings at 200°C or 500°C heat treatment has better corrosion resistance.

Mechanistic variation in the reactions of substituted acetamides in aqueous sulfuric acid

1984 ◽  
Vol 62 (11) ◽  
pp. 2401-2414 ◽  
Author(s):  
Linda M. Druet ◽  
Keith Yates
Keyword(s):  
Sulfuric Acid ◽  
Water Molecules ◽  
Acid Solutions ◽  
Reaction Products ◽  
Aqueous Sulfuric Acid ◽  
Rate Determining Step ◽  
Wide Range ◽  
Acid Catalyzed ◽  
Catalyzed Reactions ◽  
Sulfuric Acid Solutions

The acid-catalyzed reactions of acetamide 1, N-tert-butylacetamide 2, and several p-substituted N-benzylacetamides (3 = H, 4 = CH3, 5 = OCH3, 6 = Cl, 7 = NO2) have been studied as a function of acidity and temperature over a wide range of aqueous sulfuric acid solutions (0–91%). Analysis of the reaction products and rate–acidity profiles revealed that four different mechanisms are operative over different acidity regions depending on the structure of the substrate. These are: two A-2 hydrolysis mechanisms with N-acyl fission of the substrate (with participation of one or several water molecules in the rate-determining step); A-1 hydrolysis with N-alkyl fission; and sulfonation, followed by hydrolysis. These conclusions are supported by three complementary and detailed kinetic treatments based on the hydration parameter, transition state activity coefficient, and excess acidity approaches. The acidity domains of each mechanism have been established for each substrate. The mechanistic conclusions are fully supported by the different values of ΔH‡ and ΔS‡ obtained in different regions of acidity.

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