Electrochemical Aspects of Etching and Passivation of Silicon in Alkaline Solutions

1995 ◽  
Vol 386 ◽  
Author(s):  
Joong S. Jeon ◽  
Srini Raghavan
Keyword(s):  
Current Density ◽  
Corrosion Current Density ◽  
Open Circuit Potential ◽  
Corrosion Current ◽  
Open Circuit ◽  
High Resistivity ◽  
Alkaline Solutions ◽  
Current Densities ◽  
Passivation Potential ◽  
P Type

ABSTRACTElectrochemical polarization experiments were performed on Si wafers in ammoniacal solutions maintained at a pH in the range of 9.5 to 11.5. Anodic polarization of silicon yielded curves which are typical for materials that undergo passivation. The values of open circuit potential and passivation potential for p-type Si wafers were more anodic than for the n-type Si wafers. Corrosion current density of p-type Si wafers of low resistivity was lower than that of wafers of high resistivity. Corrosion current densities correlated well with surface roughness induced in alkaline solutions. Addition of surfactant or H2O2 to alkaline solutions reduced critical current density for passivation and corrosion current density.

scholarly journals Experimental evaluation of corrosion resistance of the alloys used in the fixed dental prosthesis

2015 ◽  
Vol 61 (2) ◽  
pp. 117-120
Author(s):  
Costin Coman ◽  
◽  
Raluca Monica Comăneanu ◽  
Violeta Hâncu ◽  
Horia Mihail Barbu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Current Density ◽  
Applied Research ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Artificial Saliva ◽  
Corrosion Current ◽  
Open Circuit ◽  
Metal Alloys ◽  
Fixed Dental Prosthesis

Objectives. In this study we evaluated corrosion resistance of three types of metal alloys (two NiCr and one CoCr). Methods. Samples (coded A, B, C) of circular shape, with dimensions 13 x 1.5 mm, sanded and polished, were introduced in Fusayama Meyer artificial saliva at pH 5.2 and 37 ± 0.5°C and tested in terms of corrosion resistance with a potentiostat/galvanostat (model 4000 PARSTAT, Princeton Applied Research). Results. Open circuit potential EOC [mV] ranged between 21.316 and 5.75. Corrosion potential Ecor [mV] was between -73.536 and -395.662, and the corrosion current density icor [A/cm2] was between 1.237 x 10-6 and 905.13 x 10-9. Conclusion. The best corrosion behavior in Fusayama Meyer artificial saliva at pH 5.2 and at a temperature of 37 ± 0.5°C is the alloy A, followed by the alloy C.

Effect of Preparation Conditions on Evaluation of Porous Silicon’s Morphology and Coalition with its Optical Property

2015 ◽  
Vol 713-715 ◽  
pp. 2667-2672
Author(s):  
Xi Feng Zhang ◽  
Hong Xia Dong ◽  
Ke Wei Li ◽  
Yu Wang
Keyword(s):  
Hydrofluoric Acid ◽  
Corrosion Current Density ◽  
Room Temperature ◽  
Corrosion Current ◽  
Etching Time ◽  
Photoluminescence Spectra ◽  
Preparation Conditions ◽  
Atomic Force ◽  
Current Densities ◽  
P Type

This article presents the dependence of porous silicon (PSi) morphology on preparation conditions and the coalition between morphology and optical properties. p-type (100) silicon wafers were etched in an electrolyte incorporating 1:1 (by volume) ethanol and aqueous solution of hydrofluoric acid (40 wt. %) at various etching current densities and times. Detailed information about evolution of PSi morphology with variation of preparation conditions was investigated by field emission scanning electron microscopy (FESEM) and atomic force microscope (AFM). The results have shown that the pore sizes of PSi are gradually increasing, and the thicknesses of PSi layer are increased with the speed of about 11-12 nm/s as the etching duration increased. Addition, the optimal photoluminescence of PSi is achieved in room temperature with the strongest photoluminescence spectra when the corrosion current density was 30 mA / cm2 with 30 min etching time.

Effect of Phosphorus on the Corrosion Resistance of Nickel Electrocoatings

2015 ◽  
Vol 228 ◽  
pp. 310-316
Author(s):  
B. Łosiewicz ◽  
Magdalena Popczyk ◽  
Magdalena Szklarska ◽  
Patrycja Osak
Keyword(s):  
Corrosion Resistance ◽  
Anodic Polarization ◽  
Open Circuit Potential ◽  
Electrochemical Corrosion ◽  
Amorphous Structure ◽  
Open Circuit ◽  
Alkaline Solutions ◽  
Nickel Coatings ◽  
Effective Manner ◽  
Passivation Potential

The electrodeposited Ni-P coatings are commonly used for their electrocatalytic properties towards hydrogen evolution reaction. However, their corrosion resistance in concentrated alkaline solutions is still less known. In this work, the effect of phosphorus on the resistance of nickel electrodeposits to electrochemical corrosion in 5 M KOH solution, was studied. Open circuit potential and anodic polarization measurements were performed to determine parameters of the corrosion resistance of the crystalline Ni deposit and amorphous Ni-P electrocoating. It was found that alloying of nickel with phosphorus is the effective manner of the improvement of the corrosion resistance of the nickel coatings. The obtained Ni-P electrode material contained 10 wt.% of P and revealed amorphous structure. The increase in the corrosion resistance of the Ni90P10system as compared to that determined for comparable Ni polycrystalline electrode was due to phosphate formation responsible for broad passivation potential in alkaline medium and amorphous structure.

scholarly journals Study on the Influence of AC Stray Current on X80 Steel under Stripped Coating by Electrochemical Method

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Yanyu Cui ◽  
Tao Shen ◽  
Qingmiao Ding
Keyword(s):  
Current Density ◽  
Electrochemical Method ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Open Circuit ◽  
Stray Current ◽  
Ac Power ◽  
Initial Stage ◽  
X80 Steel ◽  
Ac Interference

The effect of AC stray current density on corrosion behavior of X80 steel with stripped coating defects was studied by electrochemical method. The experimental results showed that the open circuit potential of X80 steel was shifted negatively due to the existence of AC interference. The degree of negative shift increased with the increasing of AC stray current density. And the potential after the cut of AC interference was still more negative than before. That is, the corrosion interference continued after cutting the AC power. In the initial stage of the experiment, the corrosion current density with 30A/m2 AC stray current interference was about 1.4 times of that without AC interference, while the corrosion current density with 50A/m2 AC stray current interference was about two times of that without AC interference.

Corrosion Behavior of Cobalt Alloy Coating in NaCl Solution

2020 ◽  
Vol 993 ◽  
pp. 1086-1094
Author(s):  
Yue Hou ◽  
Hai Yan Chen ◽  
Li Fan ◽  
Yu Rong Xu ◽  
Qian Cheng ◽  
...  
Keyword(s):  
Current Density ◽  
Corrosion Current Density ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Alloy Coating ◽  
Corrosion Current ◽  
Eutectic Structure ◽  
Open Circuit ◽  
The Self ◽  
Nacl Solution

Two kinds of Co-based coatings were obtained through the laser cladding (LC) and plasma transfer arc (PTA) process. The phase composition and microstructure of the coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The corrosion behaviour of the different Co-based alloy coatings in 3.5wt% NaCl solution were compared by means of open-circuit potential (OCP), polarization curve and electrochemical impedance spectroscopy (EIS). XRD and SEM measurements demonstrated that the microstructures of the two different Co-based coatings were composed of primary solid solution γ-Co and eutectic structure Cr23C6, whereas, fish-bone typed (CoCrW)6C was also detected in the coating produced by PTA. The polarization curves and EIS results showed that in 3.5wt% NaCl solution, the passivation zones of the two coatings occurred obviously, the self-corrosion potential of the two coatings shifted to the right, and the self-corrosion current density was much smaller than that of the substrate. In addition, the Co-based coating made by LC showed lower corrosion current density and larger diameter of a capacitive arc than that of Co-based coating produced by PTA, indicating the LC coating had the best corrosion resistance in the three samples.

ANTICORROSION AND REPAIR BEHAVIOR OF REC–SiO2 SILANE FILM ON CARBON STEEL

2021 ◽  
pp. 2150098
Author(s):  
JIABIN TANG ◽  
YIHE YAO ◽  
MANLI GUO ◽  
JIBO JIANG ◽  
HAISHAN CONG ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Current Density ◽  
Corrosion Current Density ◽  
Condensation Reaction ◽  
Morphological Characteristics ◽  
Corrosion Current ◽  
Element Distribution ◽  
Open Circuit ◽  
Self Healing

The synergistic effect of Ce[Formula: see text] and SiO2 nanoparticles (NPs) composite silane film on the corrosion resistance of carbon steel was researched. The preparation method of silane film is mainly hydrolysis of bis-1,2-(triethoxysilyl)ethane (BTSE) and 3-glycidoxypropyltrimethoxysilane (KH-560) under acidic conditions and condensation reaction. EDX and SEM were employed to analyze the element distribution and morphological characteristics of the coating, which confirmed the coatings were crack-free and even distribution of surface elements. The chemical bond structure characteristics of the silane film on carbon steel were analyzed by XPS, and compared with the silane film after ultrasound. It proved the bonding force of the silane film. The best corrosion current density of the silane film containing cerium is 4.65 [Formula: see text]Acm[Formula: see text]. The [Formula: see text] obtained by simulating the corrosion circuit through Zsimpwin software is 22.02[Formula: see text]k[Formula: see text]cm[Formula: see text]. On this basis, by adding different concentrations of SiO2 NPs, the corrosion current density can reach a minimum of 0.70 [Formula: see text]Acm[Formula: see text]. The simulated polarization curve [Formula: see text] was 65.13[Formula: see text]k[Formula: see text]cm[Formula: see text]. In the long-term open-circuit potential test, the potential of the silane film containing rare earth cerium increased to 38[Formula: see text]mV at a certain stage, which proves the self-healing performance of the film.

Effect of Time on Corrosion Rates in Sulfuric Acid Predicted from Electrochemical Data

CORROSION ◽  
1970 ◽  
Vol 26 (2) ◽  
pp. 79-85 ◽  
Author(s):  
A. H. WAGNER ◽  
J. R. MYERS
Keyword(s):  
Steady State ◽  
Sulfuric Acid ◽  
Current Density ◽  
Corrosion Current Density ◽  
Acid Corrosion ◽  
Corrosion Current ◽  
Ternary Alloys ◽  
Corrosion Rates ◽  
Long Time ◽  
Current Densities

Abstract Effect of time on the cathodic polarization behavior of Ni, Cr, Ti, Al, and six Ni-Cr-Al and Ni-Cr-Ti alloys was determined in hydrogen saturated, 1N sulfuric acid at 22 C (71 F). Corrosion current densities (icorr) obtained for these specimens, using the beta-extrapolation technique, were generally found to be strongly time dependent. Corrosion current densities for Ni, Cr, and the six ternary alloys decreased with time and approached steady state values after about 72 hours exposure to the electrolyte. Corrosion current density for Al decreased markedly during the initial 24-hour period; further exposure did not appreciably affect the corrosion current density. The corrosion current density for titanium decreased only slightly as the exposure time was increased. All materials exhibited steady state corrosion current densities after sufficient exposure to the acid. Corrosion rates predicted using the steady state corrosion current densities correlated well with rates obtained from long time, weight loss tests. It was established that accurate corrosion rates can be predicted from electrochemical data only after steady state corrosion current densities have been obtained.

scholarly journals A Simple and Reliable Setup for Monitoring Corrosion Rate of Steel Rebars in Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Shamsad Ahmad ◽  
Mohammed Abdul Azeem Jibran ◽  
Abul Kalam Azad ◽  
Mohammed Maslehuddin
Keyword(s):  
Current Density ◽  
Corrosion Current Density ◽  
Low Cost ◽  
Research Work ◽  
Simple Calculation ◽  
Corrosion Current ◽  
High Resistivity ◽  
Polarization Data ◽  
Ohmic Drop ◽  
Corrosion Of Steel

The accuracy in the measurement of the rate of corrosion of steel in concrete depends on many factors. The high resistivity of concrete makes the polarization data erroneous due to the Ohmic drop. The other source of error is the use of an arbitrarily assumed value of the Stern-Geary constant for calculating corrosion current density. This paper presents the outcomes of a research work conducted to develop a reliable and low-cost experimental setup and a simple calculation procedure that can be utilised to calculate the corrosion current density considering the Ohmic drop compensation and the actual value of the Stern-Geary constants calculated using the polarization data. The measurements conducted on specimens corroded to different levels indicate the usefulness of the developed setup to determine the corrosion current density with and without Ohmic drop compensation.

scholarly journals An electrochemical method to investigate the effects of compound composition on gold dissolution in thiosulfate solution

2020 ◽  
Vol 9 (1) ◽  
pp. 496-502 ◽  
Author(s):  
Zhaohui Zhang ◽  
Bailong Liu ◽  
Mei Wu ◽  
Longxin Sun
Keyword(s):  
Dissolution Rate ◽  
Current Density ◽  
Polarization Resistance ◽  
Electrochemical Method ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Gold Dissolution ◽  
Tafel Polarization ◽  
Edta Solution

AbstractThe electrochemical behavior of gold dissolution in the Cu2+–NH3–S2O32−–EDTA solution has been investigated in detail by deriving and analyzing the Tafel polarization curve, as this method is currently widely implemented for the electrode corrosion analysis. The dissolution rate of gold in Cu2+–NH3–S2O32−–EDTA solution was determined based on the Tafel polarization curves, and the effects of various compound compositions in a Cu2+–NH3–S2O32−–EDTA mixture on the corrosion potential and corrosion current density were analyzed. The results showed that the corrosion potential and polarization resistance decreased, whereas the corrosion current density increased for certain concentrations of S2O32−–NH3–Cu2+ and EDTA, indicating that the dissolution rate of gold had changed. The reason for promoting the dissolution of gold is also discussed.

scholarly journals Structure, Corrosion Resistance, Mechanical and Tribological Properties of ZrB2 and Zr-B-N Coatings

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1194
Author(s):  
Philipp Kiryukhantsev-Korneev ◽  
Alina Sytchenko ◽  
Yuriy Kaplanskii ◽  
Alexander Sheveyko ◽  
Stepan Vorotilo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Tribological Properties ◽  
Current Density ◽  
Corrosion Current Density ◽  
Elastic Recovery ◽  
Optical Emission ◽  
Corrosion Current ◽  
Impact Testing ◽  
Total Oxidation ◽  
Mechanical And Tribological Properties

The coatings ZrB2 and Zr-B-N were deposited by magnetron sputtering of ZrB2 target in Ar and Ar–15%N2 atmospheres. The structure and properties of the coatings were investigated via scanning and transmission electron microscopy, energy dispersion analysis, optical profilometry, glowing discharge optical emission spectroscopy and X-ray diffraction analysis. Mechanical and tribological properties of the coatings were investigated using nanoindentation, “pin-on-disc” tribological testing and “ball-on-plate” impact testing. Free corrosion potential and corrosion current density were measured by electrochemical testing in 1N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °С temperature interval. The coatings deposited in Ar contained 4–11 nm grains of the h-ZrB2 phase along with free boron. Nitrogen-containing coatings consisted of finer crystals (1–4 nm) of h-ZrB2, separated by interlayers of amorphous a-BN. Both types of coatings featured hardness of 22–23 GPa; however, the introduction of nitrogen decreased the coating’s elastic modulus from 342 to 266 GPa and increased the elastic recovery from 62 to 72%, which enhanced the wear resistance of the coatings. N-doped coatings demonstrated a relatively low friction coefficient of 0.4 and a specific wear rate of ~1.3 × 10−6 mm3N−1m−1. Electrochemical investigations revealed that the introduction of nitrogen into the coatings resulted in the decrease of corrosion current density in 3.5% NaCl and 1N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-В-N coatings was related to the finer grains size and increased volume of the BN phase. The samples ZrB2 and Zr-B-N resisted oxidation at 600 °C. N-free coatings resisted oxidation (up to 800 °С) and the diffusion of metallic elements from the substrate better. In contrast, Zr-B-N coatings experienced total oxidation and formed loose oxide layers, which could be easily removed from the substrate.

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