Corrosion Rate of Galvanized Steel Immersed in Saturated Solutions of Ca(OH)2in the pH Range 12–13 · 8

1983 ◽  
Vol 18 (2) ◽  
pp. 82-87 ◽  
Author(s):  
A. Macías ◽  
C. Andrade
Keyword(s):  
Corrosion Rate ◽  
Galvanized Steel ◽  
Ph Range ◽  
Saturated Solutions

Laser Welding Influence on Corrosion Rate of Galvanized Sheets of DP600 Automobilistic Alloy

2020 ◽  
Vol 1012 ◽  
pp. 436-440
Author(s):  
Viviane Teleginski Mazur ◽  
Sílvia Rosa Nascimento ◽  
Marilei de Fátima Oliveira ◽  
Willer Cézar Braz ◽  
Correard Gilson Carlos de Castro ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Open Circuit Potential ◽  
Scanning Speed ◽  
Open Circuit ◽  
Galvanized Steel ◽  
Beam Power ◽  
Laser Weld ◽  
Corrosion Studies ◽  
Laser Beam Power ◽  
Rate Behavior

Corrosion rate behavior of laser welded dual-phase galvanized steel, DP 600, has been assessed in comparison with the material without the laser weld, in 3.5% NaCl solution. Three combinations of both scanning speed and laser power parameters were selected, maintaining the thermal input of 30 J mm-1, calculated as the ratio between the laser beam power [W] and the scanning speed [mm s-1]. The corrosion studies included measurements of open circuit potential, micro and macro polarization, showing higher corrosion rates as scanning speed decreased. Optical microscopy showed the formation of a grain size refined morphology in the heat affected zone and fusion zone. A mechanism has been proposed to explain the corrosion behavior as a function of the laser parameters, which dictated the galvanized coating vaporization.

Aluminium corrosion studies. II. Corrosion rates in water

1977 ◽  
Vol 30 (4) ◽  
pp. 721 ◽  
Author(s):  
A Berzins ◽  
JV Evans ◽  
RT Lowson
Keyword(s):  
Corrosion Rate ◽  
Dissolved Oxygen ◽  
Chloride Concentration ◽  
Chloride Ions ◽  
Oxide Surface ◽  
Corrosion Rates ◽  
Saturated Water ◽  
Corrosion Studies ◽  
Competitive Action ◽  
Ph Range

The corrosion rate of aluminium in flowing neutral waters at 50�C has been determined as a function of pH, oxygen concentration and chloride concentration. The corrosion rate, At, as total aluminium lost between the 4th and 80th day was observed to be logarithmic according to At = B log t+C with a minimum rate in the pH range 5-6, and with B c. 3 x 10-5g cm2, C c. 20 x 10-5 g cm-2 and t in days for oxygen-saturated water. Saturating the water with nitrogen or adding up to 15 mg Cl- l-1 increased the corrosion rate. It was concluded that this was due to competitive action on the oxide surface, between dissolved oxygen and chloride ions.

Some thermodynamic aspects of dissolution of solid solutions of hydroxylapatites of phosphorus and arsenic

1979 ◽  
Vol 57 (19) ◽  
pp. 2662-2664 ◽  
Author(s):  
T. S. B. Narasaraju ◽  
U. S. Rai
Keyword(s):  
Solid Solutions ◽  
Free Energies ◽  
Compositional Range ◽  
Calcium Phosphorus ◽  
Ph Range ◽  
Saturated Solutions

The solubility equilibria of synthetic samples of hydroxylapatite, its arsenic isomorph, and a series of their solid solutions, spread over the entire compositional range, were investigated at 37 °C in the pH range 5.0 to 7.6 in buffered systems through microanalytical determinations of calcium, phosphorus, and arsenic in their saturated solutions. From the ionic products of the samples so determined their stoichiometric dissolution was established and their free energies of solution evaluated.

scholarly journals Effect of Fe, Ni, and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy under different pH conditions

2018 ◽  
Vol 8 (3) ◽  
pp. 241-253
Author(s):  
Mohammad Salim Kaiser ◽  
Maglub Al Nur
Keyword(s):  
Corrosion Rate ◽  
Oxide Film ◽  
Corrosion Behaviour ◽  
Chloride Ions ◽  
Surface Oxide ◽  
Surface Oxide Film ◽  
Sem Images ◽  
Optical Micrograph ◽  
Ph Conditions ◽  
Ph Range

Effect of Fe, Ni and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy was studied. The test of corrosion behaviour at different environmental pH 1, 3, 5, 7, 9, 11 and 13 was performed using conventional gravimetric measurements and complemented by resistivity, optical micrograph, scanning electron microscopy (SEM) and X-ray analyser (EDX) investigations. The highest corrosion rate was observed at pH 13 followed by pH 1, while in the pH range of 3.0 to 11, there is a high protection of surface due to formation of stable surface oxide film. The highest corrosion rate at pH 13 is due to presence of sodium hydroxide in the solution in which the surface oxide film is soluble. At pH 1, however, high corrosion rate can be attributed to dissolution of Al due to the surface attack by aggressive chloride ions. Presence of Fe, Ni and Cr in hyper-eutectic Al-Si automotive alloy has significant effect on the corrosion rate at both environmental pH values. Resistivity of alloy surfaces initially decreases at pH 1 and pH 13 due to formation of thin films. The SEM images of corroded samples immersed in pH 1 solution clearly show pores due to uniform degradation of the alloy. In pH 13 solution, however, the corrosion layer looks more packed and impermeable.

scholarly journals Corrosion Monitoring of Galvanized Steel in Simulated Wet-Dry Cyclic Condition in 0.05 M NaCl Solution

1970 ◽  
Vol 8 (8) ◽  
pp. 76-80 ◽  
Author(s):  
AP Yadav
Keyword(s):  
Corrosion Rate ◽  
Corrosion Potential ◽  
Early Stage ◽  
Ac Impedance ◽  
Galvanized Steel ◽  
Corrosion Mechanism ◽  
Corrosion Monitoring ◽  
Cyclic Condition ◽  
Impedance Technique ◽  
Time Of Wetness

The corrosion monitoring of galvanized steel in 1 h wet and 7 h dry cyclic condition in 0.05 M NaCl has been carried out using AC impedance technique. During the wet-dry cycles, the polarization resistance, Rp, and solution resistance, Rs, were continuously monitored. The instantaneous corrosion rate of the coating was estimated from the obtained Rp-1 and time of wetness (TOW) was determined from the Rs values. The corrosion potential, Ecorr, was measured twice a day during the immersion period of wet-dry cycle. The corrosion was accelerated by the wet-dry cycles in the early stage followed by a decrease in the final stage of wet-dry cycle. The corrosion potential shifted to more negative direction for the first 8 cycles due to dissolution of air formed oxide. A gradual shift in the corrosion potential with the progress of corrosion in the later stage of the wet-dry cycle was observed due to deposition of corrosion products. The corrosion mechanism of galvanized steel is discussed based on the results of corrosion monitoring and corrosion potential variation. Key words: Atmospheric corrosion; Galvanized steel; AC Impedance; Corrosion rate. DOI: 10.3126/sw.v8i8.3855 Scientific World Vol.8(8) 2010 pp.76-80

Steel Corrosion Patterns in Neutral and Alkaline Iron Oxide Slurry

2021 ◽  
pp. 142-155
Author(s):  
V.A. Shelontsev ◽  
I.G. Gorichev ◽  
A.V. Kuzin ◽  
I.V. Gerasimova ◽  
E.A. Eliseeva
Keyword(s):  
Iron Oxide ◽  
Corrosion Rate ◽  
Dissolved Oxygen ◽  
Polarization Resistance ◽  
Gravimetric Method ◽  
Sharp Decrease ◽  
Steel Corrosion ◽  
Chloride Ions ◽  
Diffusion Control ◽  
Ph Range

The study identifies and theoretically substantiates the steel corrosion patterns in aqueous slurry of iron-ore concentrate. The purpose of the study was to examine the effect that the content of dissolved oxygen(PO2), pH, the concentration of chloride ions (CCl-) and the rate of movement of the iron oxide slurry (ω) produce on the corrosion losses of steel 20. Comparative analysis of the corrosion rate values obtained by the gravimetric method and the polarization resistance method showed that the reciprocal of the polarization resistance and the corrosion rate change symbatically with increasing pH, the corrosion rate values are quantitatively well consistent with each other. To identify the corrosion patterns, the method of polarization resistance was used. The dependence of the corrosion rate (ρ) on рН revealed two characteristic areas: in the first one, there is no dependence of the rate on pH (6.5--9.0); in the second one, there is a sharp decrease in corrosion losses when the pH goes from 9.0 to 12.5. For pH = 6.5--9.0, the corrosion rate increases linearly with an increase in the partial pressure of oxygen, and corrosion losses in the slurry are higher than in the background solution. The dependence ρ(√ω) is linear over the entire pH range (6.0--9.0), which indicates the diffusion control of the corrosion process. Findings of research show that in order to protect carbon steel from corrosion in the iron oxide slurry, it is necessary to take into account the pH and О2 concentration. Optimal reduction of corrosion losses can be achieved by alkalizing the slurry and removing dissolved oxygen

Numerical Modeling for Corrosion Rate between Heat-affected Zone and Unaffected Base Metal of Galvanized Steel Welded by Brazing

2021 ◽  
Author(s):  
Adisak Pinyo ◽  
Sompong Bangyeekhan ◽  
Trinet Yingsamphancharoen ◽  
Aphichart Rodchanarowan
Keyword(s):  
Numerical Modeling ◽  
Corrosion Rate ◽  
Potential Theory ◽  
Base Metal ◽  
Zinc Coating ◽  
Galvanized Steel ◽  
Mixed Potential ◽  
Corrosion Rates ◽  
Faraday’S Law ◽  
Density Values

Brazing of galvanized steel causes decaying of the zinc coating and decreasing of corrosion resistant on heataffected zone (HAZ) and weldment. The corrosion rates among the HAZ, unaffected base metal (UBM), and weldment of galvanized steel welded by brazing were numerically modeled by COMSOL Multiphysics. The numerically modeled current density values from various zones, such as the couples between the HAZ and the UBM, between the weldment and the HAZ, and between the UBM and steel were used to calculate the corrosion rates. In this work, two different methods based on Faraday’s Law, the mixed potential theory and the Numerical modeling, were compared for calculations of the corrosion rates of each region. Using the mixed potential theory, the calculated corrosion rates of region I, II, III, IV, V and VI were 0.853, 0.284, 2.105,1.754, 2.028 and 0.554 mm/y, respectively. Where as based on the Numerical modeling, these rates of all regions were 0.918, 0.275, 2.198, 1.904, 2.151, and 0.566 mm/y, in orderly. These comparisons suggested that the corrosion rates obtained from two methods were similar. However, the results showed that the Numerical modeling method could predict the corrosion rate with less error.

Pulse radiolysis: evidence for the reaction of HO2 with NO2 in aqueous solution

1978 ◽  
Vol 56 (14) ◽  
pp. 1961-1964 ◽  
Author(s):  
Harry Callender Sutton ◽  
William Arthur Seddon ◽  
Fred Charles Sopchyshyn
Keyword(s):  
Aqueous Solution ◽  
Formic Acid ◽  
Rate Constant ◽  
Pulse Radiolysis ◽  
First Order ◽  
Data Support ◽  
Radiation Induced ◽  
Three Stages ◽  
Ph Range ◽  
Saturated Solutions

Nitroform is the major radiation induced species observed after the pulse radiolysis of acidic oxygen saturated solutions of tetranitromethane (TNM) and formic acid. It is formed in three stages, of which a major component at pH < 3 is first order with t1/2 = 49 s, independent of [TNM] and pH. Evidence is provided for the reactions[Formula: see text]in which k14 = 0.014 ± 0.002 s−1. The data support similar conclusions reached previously in rapid mixingexperiments (1) from which it was concluded that k3 = 4 × 109 dm3 mol−1 s−1.Analysis of the fastest component of nitroform production over the pH range 1–4 shows that the COOH radical reduces TNM to nitroform with a rate constant about four times greater than that for its reaction with oxygen to produce HO2.

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