scholarly journals Galvanic Corrosion Between Ti/Ti6Al4V and Various Dental Alloys

2017 ◽  
Vol 6 (3) ◽  
pp. 221 ◽  
Author(s):  
Daniel Mareci ◽  
Catalin Bocanu ◽  
Neculai Aelenei ◽  
Gheorghe Nemtoi
Keyword(s):  
Corrosion Potential ◽  
Galvanic Corrosion ◽  
Surrounding Medium ◽  
Electrochemical Techniques ◽  
Corrosion Process ◽  
Dental Alloys ◽  
Corrosion Rates ◽  
Current Densities ◽  
Titanium Alloy Ti6al4v ◽  
Electrochemical Potentials

<p>The corrosion tendencies of metals are related with their position in the electromotive series. These electrode potential degrees may change due to the composition of the alloys, the surrounding medium or due to the alterations in the composition because of the recurrent costing. The galvanic corrosion appears when different electrochemical potentials are bound to one another and the electrical conductibility is assured by the presence of an electrolyte. It is difficult to avoid coupling of different metals, a problem concerning the choice of the alloy used for the implant bone supra-structure. One has studied the galvanism of several couples formed between a dental implant and diverse dental alloys in Afnor saliva. The electrochemical behavior of 8 commercial dental alloy superstructures with titanium and titanium alloy (Ti6Al4V) implants was investigated by electrochemical techniques. Non-precious alloys were Ni-Cr based (Wiron NT and Verasoft), Co-Cr based (Vitallium alloy) and Cu based (Gaudent). Semi-precious alloys were Ag-Pd based (RX91 and Unique White). The precious alloys were Au-Pd based (Ceram) and Au-Ag based (Argenco). Some of the corroded and non-corroded surfaces were observed by optical microscopy. From linear polarization curves the corrosion potential and the current densities were evaluated. The results showed very low corrosion rates, ranking from 10<sup>-6</sup> to 10<sup>-9</sup> A/cm<sup>2</sup>. All the results obtained indicate the fact that the corrosion process intensity corresponding to the coupling between titanium (respectively Ti6Al4V) and semi-precious alloys is reduced. The surface of precious and semi-precious alloys is not attacked, but the titanium (Ti6Al4V) surface is oxidized in time.</p>

scholarly journals Corrosion Behavior of Al in Ethanol–Gasoline Blends

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5544
Author(s):  
Alfredo Brito-Franco ◽  
Jorge Uruchurtu ◽  
Isai Rosales-Cadena ◽  
Roy Lopez-Sesenes ◽  
Sergio Alonso Serna-Barquera ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Sugar Cane ◽  
Electrochemical Noise ◽  
Electrochemical Impedance ◽  
Pure Aluminum ◽  
Electrochemical Techniques ◽  
Intermediate Compound ◽  
Corrosion Process ◽  
Corrosion Rates ◽  
Adsorption Desorption

The corrosion behavior of pure aluminum (Al) in 20 v/v% ethanol–gasoline blends has been studied using electrochemical techniques. Ethanol was obtained from different fruits including sugar cane, oranges, apples, or mangos, whereas other techniques included lineal polarization resistance, electrochemical noise, and electrochemical impedance spectroscopy for 90 days. Results have shown that corrosion rates for Al in all the blends were higher than that obtained in gasoline. In addition, the highest corrosion rate was obtained in the blend containing ethanol obtained from sugar cane. The corrosion process was under charge transfer control in all blends; however, for some exposure times, it was under the adsorption/desorption control of an intermediate compound. Al was susceptible to a localized, plotting type of corrosion in all blends, but they were bigger in size and in number in the blend containing ethanol obtained from sugar cane.

Effects of Stress and Plastic Deformation on the Corrosion of Steel

CORROSION ◽  
1970 ◽  
Vol 26 (5) ◽  
pp. 189-199 ◽  
Author(s):  
W. D. FRANCE
Keyword(s):  
Plastic Deformation ◽  
Electrochemical Techniques ◽  
Chloride Ions ◽  
Localized Corrosion ◽  
Dissolution Behavior ◽  
Potential Range ◽  
Chemical Corrosion ◽  
Effects Of Ph ◽  
Current Densities ◽  
The Stability

Abstract The rate and type of corrosion exhibited by mild steel in the annealed, stressed, and plastically deformed state have been investigated. Precise electrochemical techniques provided potential and polarization data to supplement the results of chemical corrosion tests. Experiments were conducted in 0.6M NH4NO3 solutions in which steel exhibits active-passive dissolution behavior as well as localized corrosion. At active potentials, the anodic polarization curves for annealed and deformed specimens were nearly identical, with only slight increases in current densities for the deformed steel. Results at passive potentials demonstrated that increased plastic deformation can markedly decrease the passive potential range, the stability of passivity, and the ability to passivate. At certain passive potentials, the deformed steel exhibited current densities that were 400 times greater than those for annealed steel. The effects of pH, chloride ions, and crevices on the corrosion of deformed steel were examined in detail. The differences between the dissolution behavior of annealed and deformed steel were most distinctive in the approximate pH range of 3 to 6. This work is relevant to the understanding of the initiation of localized corrosion and to anodic protection.

Chromate and Molybdate Inhibitors Effects on Corrosion Charateristic of API 5L Grade B in a Brine Water Solution Containing 8 % NaCl

2021 ◽  
Vol 892 ◽  
pp. 115-123
Author(s):  
Viktor Malau ◽  
Wisnu Hakiki
Keyword(s):  
Corrosion Resistance ◽  
Oil And Gas ◽  
Corrosion Potential ◽  
Water Solution ◽  
Sodium Molybdate ◽  
Corrosion Process ◽  
Sodium Chromate ◽  
Polarization Method ◽  
Steel Pipes ◽  
Piping Systems

Piping systems at gathering stations in the oil and gas industries often fail due to corrosion attacks from the brine water solution containing 8% NaCl that flows through the system. This solution is highly corrosive on the API 5L grade B steel pipes, thereby shortening its lifespan, with an increase in the frequency of pipe replacements. However, the corrosion resistance of API 5L grade B pipes can be improved by using chromate and molybdate inhibitors. Therefore, the objective of this research is to improve the corrosion resistance of the steel pipes using sodium chromate (Na2CrO4) and sodium molybdate (Na2MoO4) inhibitors with concentrations of 0.2, 0.4, 0.6, 0.8 and 1,0%. This research also aim to determine the optimum concentration of inhibitors to produce minimum corrosion rate, by testing the brine water solution containing 8% NaCl through the potentiodynamic polarization method. The results show that generally, the addition of sodium chromate and sodium molybdate inhibitors to the brine solution causes the steel pipes to be more resistant to corrosion. Furthermore, the sodium chromate inhibitor concentration of 0.6% produces the greatest corrosion potential of – 400 mV with the lowest rate of 0.38 mpy, while sodium molybdate concentration of 0.4% produces the highest corrosion potential of – 385 mV with the lowest rate of 0.34 mpy. The results of SEM observations at 0.4% sodium molybdate concentration showed that the corrosion inhibition/passivation effect of the inhibitor made the steel surface smoother, while the sodium chromate inhibitor at similar percentage failed to reach the optimal concentration to inhibit the corrosion process.

scholarly journals Corrosion resistance of metalized layers on steel parts in ventilation mill

10.30544/340 ◽  
2018 ◽  
Vol 24 (2) ◽  
pp. 123-132
Author(s):  
Bore V. Jegdic ◽  
Bojana M. Radojković ◽  
Biljana M. Bobić ◽  
Marija M. Krmar ◽  
Slavica Ristić
Keyword(s):  
Corrosion Rate ◽  
Base Metal ◽  
Galvanic Corrosion ◽  
Thermal Power ◽  
Electrochemical Techniques ◽  
General Corrosion ◽  
Hvof Process ◽  
The Difference ◽  
Local Dissolution ◽  
Oxygen Fuel

Corrosion behavior of metalized layers, obtained by Plasma Transferred Arc (PTA) process and by High-Velocity Oxygen Fuel (HVOF) process with the purpose to improve the wear resistance of vital parts of ventilation mill in a thermal power plant, has been tested. The test is performed using three electrochemical techniques, in a solution containing chloride and sulfate ions. It is shown that the steel surface (base metal) dissolves uniformly, without pitting or other forms of local dissolution. Morphology of metalized layers surface indicates that dissolution is non-uniform, but it still can be considered as general corrosion. The corrosion rate of base metal and metalized layer obtained by PTA process is rather low, while the corrosion rate of the metalized layer obtained by HVOF process is much higher. Also, the difference in corrosion potentials between the base metal and the HVOF layer is pretty high but slightly less than maximum allowed difference (prescribed by the standard), to avoid excessive galvanic corrosion. The values of corrosion rate obtained by different electrochemical techniques are in excellent agreement.

scholarly journals Reprocessing of LiH in Molten Chlorides

2008 ◽  
Vol 63 (5-6) ◽  
pp. 377-384
Author(s):  
Patrick J. Masset ◽  
Armand Gabriel ◽  
Jean-Claude Poignet
Keyword(s):  
Process Design ◽  
Diffusion Coefficients ◽  
Electrochemical Techniques ◽  
Hydrogen Gas ◽  
Standard Potential ◽  
Molten Chlorides ◽  
Metallic Lithium ◽  
Production Of Hydrogen ◽  
Current Densities ◽  
Molten Phase

LiH was used as inactive material to stimulate the reprocessing of lithium tritiate in molten chlorides. The electrochemical properties (diffusion coefficients, apparent standard potentials) were measured by means of transient electrochemical techniques (cyclic voltammetry and chronopotentiometry). At 425 ºC the diffusion coefficient and the apparent standard potential were 2.5 · 10−5 cm2 s−1 and −1.8 V vs. Ag/AgCl, respectively. For the process design the LiH solubility was measured by means of DTA to optimize the LiH concentration in the molten phase. In addition electrolysis tests were carried out at 460 ºC with current densities up to 1 A cm−2 over 24 h. These results show that LiH may be reprocessed in molten chlorides consisting in the production of hydrogen gas at the anode and molten metallic lithium at the cathode.

Prediction and Measurement of Corrosion Rates of Stainless Steel in Concentrated Sulfuric Acid

CORROSION ◽  
10.5006/0709 ◽  
2013 ◽  
Vol 69 (6) ◽  
pp. 543-550 ◽  
Author(s):  
S. Jones ◽  
K. Coley ◽  
J. Kish
Keyword(s):  
Stainless Steel ◽  
Sulfuric Acid ◽  
Corrosion Behavior ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Corrosion Rates ◽  
Transient Nature ◽  
Concentrated Sulfuric Acid

When exposed to concentrated sulfuric acid, stainless steel exhibits unique electrochemical behavior. This behavior can be observed as an oscillation in open-circuit potential between the active and passive states. The transient nature of the corrosion behavior under these conditions results in a distinct challenge for measuring and predicting corrosion rates. Using a series of commercial alloys with various nickel contents, this paper outlines the utilization of electrochemical experimentation to refine the prediction of corrosion rates. The paper also discusses some of the difficulties associated with many traditional electrochemical techniques such as potentiodynamic scans when used for characterizing systems that undergo oscillations in open-circuit potential.

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