scholarly journals Electrochemical Noise Analysis of the Corrosion of Titanium Alloys in NaCl and H2SO4 Solutions

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 105
Author(s):  
Jesús Manuel Jáquez-Muñoz ◽  
Citlalli Gaona-Tiburcio ◽  
Jose Cabral-Miramontes ◽  
Demetrio Nieves-Mendoza ◽  
Erick Maldonado-Bandala ◽  
...  
Keyword(s):  
Titanium Alloys ◽  
Electrochemical Noise ◽  
Noise Analysis ◽  
Passive Layer ◽  
Polynomial Method ◽  
Nacl Solution ◽  
Hilbert Huang Transform ◽  
Ti Alloys ◽  
Density Analysis ◽  
Corrosive Environments

Titanium alloys have been used in aerospace, aeronautic, automotive, biomedical, structural, and other applications because titanium alloys have less density than materials like steel and support higher stress than Al-alloys. However, components made of titanium alloys are exposed to corrosive environments, the most common being industrial and marine atmospheres. This research shows the corrosion behavior of three titanium alloys, specifically Ti-CP2, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V with α, near α, and α + β alloys phases. Alloys were exposed in two electrolytes to a 3.5 wt. % H2SO4 and NaCl solution at room temperature, and their electrochemical behavior was studied by electrochemical noise technique (EN) according to ASTM ASTM-G199 standard. EN signal was filtered by three different methods, and the polynomial method was employed to obtain Rn, kurtosis, skew, and the potential spectral density analysis (PSD). The wavelets method was used, from which energy dispersion plots were obtained. The last method was Hilbert–Huang Transform (HHT), where Hilbert Spectra were analyzed. Results indicated that Rn compared with PSD showed that Ti-6Al-2Sn-4Zr-2Mo presented less dissolution in both electrolytes. Statistical methods showed that the passive layer created on Ti alloys’ surfaces is unstable; this condition is notable for Ti-6Al-2Sn-4Zr-2Mo in NaCl solution.

scholarly journals Frequency Analysis of Transients in Electrochemical Noise of Superalloys Waspaloy and Ultimet

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 702
Author(s):  
Jesús Manuel Jáquez-Muñoz ◽  
Citlalli Gaona-Tiburcio ◽  
Jose Cabral-Miramontes ◽  
Demetrio Nieves-Mendoza ◽  
Erick Maldonado-Bandala ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Electrochemical Noise ◽  
Localized Corrosion ◽  
Polynomial Method ◽  
Widespread Application ◽  
Power Spectral ◽  
Different Temperatures ◽  
Density Analysis ◽  
Power Spectral Density Analysis ◽  
Critical Components

Nickel or Cobalt-based superalloys represent an important class of engineering materials, finding widespread application in critical components within the gas turbine engines used for jet propulsion and electricity generation. This research aimed at the frequency analysis of transients in electrochemical noise of Waspaloy and Ultimet superalloys, immersed in 3.5 wt.% in H2SO4 and NaCl solutions at two different temperatures, 25 and 60 °C. Localized corrosion behavior of superalloys was assessed using the electrochemical noise technique (EN) according to ASTM-G199 standard. Three different statistical methods filtered the EN signal, and the polynomial method was employed to obtain the noise resistance (Rn), the localization index (LI), skew and kurtosis, and the power spectral density analysis (PSD). Results indicate that the current and potential noise transients have a better behavior with better clarity when a polynomial is used to show a localized corrosion kurtosis for both superalloys.

Corrosion Behavior of Die-Cast and Thixocast AXJ530 Magnesium Alloy in Chloride Medium

2006 ◽  
Vol 15-17 ◽  
pp. 449-454 ◽  
Author(s):  
Sofiene Amira ◽  
M. Shehata ◽  
Dominique Dubé ◽  
R. Tremblay ◽  
Edward Ghali
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Electrochemical Noise ◽  
Noise Analysis ◽  
Nacl Solution ◽  
Chloride Medium ◽  
Die Cast ◽  
Immersion Technique ◽  
Superior Corrosion Resistance

The corrosion behavior of AXJ530 magnesium alloy in 3.5% NaCl solution at 25°C and pH 7.25 has been studied. Die-cast and thixocast specimens were tested using constant immersion technique, potentiodynamic polarization measurements and electrochemical noise analysis. The microstructure of cast specimens and their surface aspect after corrosion tests were analysed and compared. The results show that thixocast specimens have the best corrosion resistance. Their superior corrosion resistance can be attributed mainly to the presence of large pre-existing α-Mg grains.

scholarly journals Susceptibility to Pitting Corrosion of Ti-CP2, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V Alloys for Aeronautical Applications

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1002
Author(s):  
Jesus Jaquez-Muñoz ◽  
Citlalli Gaona-Tiburcio ◽  
Alejandro Lira-Martinez ◽  
Patricia Zambrano-Robledo ◽  
Erick Maldonado-Bandala ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Titanium Alloys ◽  
High Performance ◽  
Room Temperature ◽  
Corrosion Potential ◽  
Passive Layer ◽  
Ti Alloys ◽  
Power Spectral ◽  
Electrochemical Parameters ◽  
Cyclic Potentiodynamic Polarization

Titanium alloys are used in different industries like biomedical, aerospace, aeronautic, chemical, and naval. Those industries have high requirements with few damage tolerances. Therefore, they are necessary to use materials that present fatigue, mechanical, and corrosion resistance. Although Ti-alloys are material with high performance, they are exposed to corrosion in marine and industrial environments. This research shows the corrosion behavior of three titanium alloys, specifically Ti CP2, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V. Alloys were exposed on two electrolytes to a 3.5 wt % H2SO4 and NaCl solutions at room temperature using cyclic potentiodynamic polarization (CPP) and electrochemical noise (EN) according to ASTM G61 and ASTM G199 standards. CPP technique was employed to obtain electrochemical parameters as the passivation range (PR), corrosion type, passive layer persistence, corrosion potential (Ecorr), and corrosion rate. EN was analyzed by power spectral density (PSD) in voltage. Results obtained revealed pseudopassivation in CPP and PSD exposed on NaCl for Ti-6Al-2Sn-4Zr-2Mo, indicating instability and corrosion rate lower. However, Ti-6Al-4V presented the highest corrosion rate in both electrolytes. Ti-6Al-2Sn-4Zr-2Mo revealed pseudopassivation in CPP and PSD in NaCl, indicating a passive layer unstable. However, the corrosion rate was lower in both solutions.

scholarly journals A Comparative Study of Corrosion AA6061 and AlSi10Mg Alloys Produced by Extruded and Additive Manufacturing

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5793
Author(s):  
Francisco Estupiñan-López ◽  
Citlalli Gaona-Tiburcio ◽  
Jesús Jáquez-Muñoz ◽  
Patricia Zambrano-Robledo ◽  
Erick Maldonado-Bandala ◽  
...  
Keyword(s):  
Time Series ◽  
Statistical Analysis ◽  
Additive Manufacturing ◽  
Spectral Density ◽  
Corrosion Behavior ◽  
Room Temperature ◽  
Electrochemical Noise ◽  
Laser Melting ◽  
Hilbert Huang Transform ◽  
Density Analysis

The aim of this work was to evaluate the corrosion behavior of the AA6061 and AlSi10Mg alloys produced by extruded and additive manufacturing (selective laser melting, SLM). Alloys were immersed in two electrolytes in H2O and 3.5 wt. % NaCl solutions at room temperature and their corrosion behavior was studied by electrochemical noise technique (EN). Three different methods filtered EN signals, and the statistical analysis was employed to obtain Rn, the localization index (LI), Kurtosis, skew, and the potential spectral density analysis (PSD). The Energy Dispersion Plots (EDP) of wavelets method was employed to determine the type of corrosion and the Hilbert–Huang Transform (HHT), analyzing the Hilbert Spectra. The result indicated that the amplitude of the transients in the time series in potential and current is greater in the AlSi10Mg alloy manufactured by additive manufacturing. The amplitude of the transients decreases in both alloys (AA6061 and AlSi10Mg) as time increases.

METHODS OF ELECTROCHEMICAL NOISE ANALYSIS FOR INVESTIGATION OF CORROSION PROCESSES

2006 ◽  
Vol 06 (02) ◽  
pp. R1-R9 ◽  
Author(s):  
JANUSZ SMULKO
Keyword(s):  
Corrosion Rate ◽  
Polarization Resistance ◽  
Electrochemical Noise ◽  
Noise Analysis ◽  
Electrochemical Corrosion ◽  
Passive Layer ◽  
Corrosion Monitoring ◽  
Uniform Corrosion ◽  
Voltage Fluctuations ◽  
Different Types

Electrochemical corrosion processes can be investigated by observation of charge flows between the electrolyte and the corroding metal. Usually, the charge flows are observed as spontaneous current and voltage fluctuations (electrochemical noise) in a three-electrode setup. Different types of corrosion processes can be recognized by electrochemical noise analysis. Uniform corrosion rate can be evaluated by estimation of polarization resistance between the metal and electrolyte. Local corrosion events (breakdowns of the passive layer) that produce characteristic transients observed in noise can be detected as well. Different methods of electrochemical noise analysis are presented in a brief review. The limitations and advantages of the proposed methods for corrosion monitoring and research are underlined. The experimental results are also discussed.

Direct Observation of the Diffusionless β → β + ω Transformation in Titanium Alloys

1971 ◽  
Vol 29 ◽  
pp. 122-123
Author(s):  
N. E. Paton ◽  
D. de Fontaine ◽  
J. C. Williams
Keyword(s):  
Electron Microscope ◽  
Titanium Alloys ◽  
Direct Observation ◽  
Dark Field ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Selected Area Electron Diffraction ◽  
Ti Alloys ◽  
Thin Foils ◽  
Field Device

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.

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