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.

Electrochemical Measurement of Corrosion

CORROSION ◽  
1970 ◽  
Vol 26 (5) ◽  
pp. 171-176 ◽  
Author(s):  
M. E. INDIG ◽  
C. GROOT
Keyword(s):  
Weight Gain ◽  
Corrosion Rate ◽  
Redox Reactions ◽  
Electrochemical Techniques ◽  
Electrochemical Measurement ◽  
Alloy 600 ◽  
Measured Weight ◽  
Dissolved Hydrogen ◽  
The Difference ◽  
Good Agreement

Abstract The results of electrochemical measurements on the corrosion of NiCrFe Alloy 600 and Zircaloy-2 in slightly alkaline lithiated water at 288 C (550 F) are presented. The study showed that, in the presence of dissolved hydrogen at the level of 35 Scc/kg-H2O, the electrochemical techniques could not be used to measure the corrosion rate of NiCrFe Alloy 600. However, the measurements on Zircaloy-2 were unaffected by the presence of hydrogen, and good agreement between the electrochemically determined weight gain and the directly measured weight gain resulted. The difference between the behavior of the two alloys is explained by the ease with which redox reactions involving hydrogen occur on the NiCrFe Alloy 600 surfaces.

scholarly journals Electrochemical Study of Ni20Cr Coatings Applied by HVOF Process in ZnCl2-KCl at High Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
J. Porcayo-Calderón ◽  
O. Sotelo-Mazón ◽  
M. Casales-Diaz ◽  
J. A. Ascencio-Gutierrez ◽  
V. M. Salinas-Bravo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
304 Stainless Steel ◽  
Experimental Conditions ◽  
Corrosive Media ◽  
Linear Polarization Resistance ◽  
Potentiodynamic Polarization Curves ◽  
Hvof Process ◽  
Oxygen Fuel

Corrosion behavior of Ni20Cr coatings deposited by HVOF (high velocity oxygen-fuel) process was evaluated in ZnCl2-KCl (1 : 1 mole ratio) molten salts. Electrochemical techniques employed were potentiodynamic polarization curves, open circuit potential, and linear polarization resistance (LPR) measurements. Experimental conditions included static air and temperatures of 350, 400, and 450°C. 304-type SS was evaluated in the same conditions as the Ni20Cr coatings and it was used as a reference material to assess the coatings corrosion resistance. Coatings were evaluated as-deposited and with a grinded surface finished condition. Results showed that Ni20Cr coatings have a better corrosion performance than 304-type SS. Analysis showed that Ni content of the coatings improved its corrosion resistance, and the low corrosion resistance of 304 stainless steel was attributed to the low stability of Fe and Cr and their oxides in the corrosive media used.

scholarly journals Temperature-Related Corrosion Resistance of AISI 1010 Carbon Steel in Sulfolane

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2563 ◽  
Author(s):  
Julian Kubisztal ◽  
Bożena Łosiewicz ◽  
Paulina Dybal ◽  
Violetta Kozik ◽  
Andrzej Bak
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Electrochemical Techniques ◽  
Protective Layer ◽  
Corrosion Damage ◽  
Product Layer ◽  
General Corrosion ◽  
Industrial Systems ◽  
Surface Corrosion ◽  
Severe Impairment

Sulfolane-induced corrosion can lead to severe impairment in industrial systems. Therefore, determination of solvent corrosivity is valid. Under standard conditions, pure sulfolane is considered to be thermally stable and chemically inert, hence non-aggressive towards carbon/stainless steel. Unfortunately, the sulfolane-evoked corrosion of the industrial installations is observed for sulfolane-based systems polluted by small quantities of oxygen, water and some oxidizing agents. Moreover, sulfolane decomposition with formation of corrosive (by-)products can be escalated by some process parameters, e.g., temperature. The main objective of this study was to determine the corrosion resistance of AISI 1010 steel immersed in sulfolane at temperatures ranging from 25 to 230 °C. Evaluation of the corrosion damage was carried out using electrochemical techniques and scanning probe/electron microscopy, respectively. The general corrosion tendency, corrosion rate and surface corrosion degree were taken into account as well. It was noticed that the corrosion rate linearly increases with the enhancement of sulfolane temperature. Moreover, the interfacial reaction of steel with sulfolane resulted in the formation of corrosion product layer, which is a physical barrier between the corrosive environment and steel improving corrosion resistance of the latter. In fact, the increment of the sulfolane temperature caused a gradual breakdown of the protective layer and the increase in the corrosion degree of the investigated steel. Finally, it was found that the corrosion degree doubles approximately every 42 °C.

scholarly journals Microstructure and Corrosion of Cast Magnesium Alloy ZK60 in NaCl Solution

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3833
Author(s):  
Zhen Li ◽  
Zeyin Peng ◽  
Kai Qi ◽  
Hui Li ◽  
Yubing Qiu ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Corrosion Rate ◽  
Electrochemical Techniques ◽  
Second Phase ◽  
Corrosion Mechanism ◽  
Schematic Model ◽  
General Corrosion ◽  
Second Phase Particles ◽  
Cast Magnesium Alloy ◽  
Cast Magnesium

In this work, the effects of the microstructure and phase constitution of cast magnesium alloy ZK60 (Mg-5.8Zn-0.57Zr, element concentration in wt.%) on the corrosion behavior in aqueous NaCl (0.1 mol dm−3) were investigated by weight-loss measurements, hydrogen evolution tests, and electrochemical techniques. The alloy was found to be composed of α-Mg matrix, with large second-phase particles of MgZn2 deposited along grain boundaries and a Zr-rich region in the central area of the grains. The large second-phase particles and the Zr-rich regions were more stable than the Mg matrix, resulting in a strong micro-galvanic effect. A filiform corrosion was found. It originated from the second-phase particles in the grain boundary regions in the early corrosion period. The filaments gradually occupied most areas of the alloy surface, and the general corrosion rate decreased significantly. Corrosion pits were developed under filaments. The pit growth rate decreased over time; however, it was about eight times larger than the general corrosion rate. A schematic model is presented to illustrate the corrosion mechanism.

scholarly journals Corrosion of Steel Rebars in Anoxic Environments. Part I: Electrochemical Measurements

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2491
Author(s):  
Elena Garcia ◽  
Julio Torres ◽  
Nuria Rebolledo ◽  
Raul Arrabal ◽  
Javier Sanchez
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Chloride Content ◽  
Offshore Platforms ◽  
Anoxic Conditions ◽  
Current Limit ◽  
Anoxic Environments ◽  
Corrosion Of Steel ◽  
Steel Rebars

The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm2, irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant (bc) to be 180 mV dec−1, and the current limit yielded an ilim value of 0.98 µA/cm2. On the other hand, the corrosion potential would lie most likely in the −900 mVAg/AgCl to −1000 mVAg/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm2 to 0.22 µA/cm2. The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.

Characterization of WC-Co Coatings Using HP/HVOF Process

1996 ◽  
Author(s):  
S.Y. Hwang ◽  
B.G. Seong ◽  
M.C. Kim
Keyword(s):  
Wear Resistance ◽  
X Ray Diffraction ◽  
High Carbon ◽  
Properties Of Coatings ◽  
X Ray ◽  
Hvof Process ◽  
Number Of Passes ◽  
Oxygen Fuel

Abstract To maintain surface roughness of process rolls in cold rolling steel plants, WC-Co coatings have been known to be effective ones. In this study, a high pressure/high velocity oxygen fuel (HP/HVOF) process was used to obtain WC-Co coatings. To get the best quality of coatings, WC-Co coatings are sprayed with numerous powders made by various processes. These powders include agglomerated sintered powders, fused-crushed powders, extra high carbon WC-Co powders and (W2C, WC)-Co powders. After spraying, properties of coatings such as hardness, wear resistance. X-ray diffraction, and microstructures were analyzed. For coatings produced by agglomerated-sintered powders, hardness of the coating increased as power levels and the number of passes were increased. In case of the coatings produced by fused-crushed powders, a very low deposition rate was obtained due to a low flowablity of the powders. In addition, the WC-Co coatings sprayed with extra carbon content of WC-Co did not show improved hardness and wear resistance. Also, some decomposition of WC was observed in the coating. Finally, the coatings produced by (W2C, WC)-Co powders produced higher hardness and lower wear resistance coating.

Surface roughness changes caused by the galvanic corrosion between a titanium abutment and base metal alloy

2011 ◽  
Vol 49 (1) ◽  
pp. 65 ◽  
Author(s):  
Jung-Jin Lee ◽  
Kwang-Yeob Song ◽  
Seung-Keun Ahn ◽  
Ju-Mi Park
Keyword(s):  
Surface Roughness ◽  
Base Metal ◽  
Galvanic Corrosion ◽  
Metal Alloy ◽  
Base Metal Alloy

scholarly journals Effect of Structural Modification on Corrosion Behavior of Hypo Eutectic Al-Si Alloy

2018 ◽  
Vol 778 ◽  
pp. 16-21
Author(s):  
Muhammad Mansoor ◽  
Muhammad Kamran Yaseen ◽  
Shaheed Khan
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Earth Metal ◽  
Alloy System ◽  
Eutectic Phase ◽  
Al Alloy ◽  
General Corrosion ◽  
Corrosion Properties ◽  
Unmodified Alloy ◽  
Cast Alloys

Al-Si eutectic cast alloys are widely used in aeronautical and automobile industries where significantly high strength, toughness and wear resistance are required. This class of cast alloys exhibit relatively low corrosion resistance in brine environments. The mechanical properties of the alloy system mainly depend upon the shape of Si rich eutectic phase, which mainly has acicular geometry. In present research, the effect of modified microstructure of 12 wt. % Si-Al alloy on corrosion behavior was studied. The needle like Si rich eutectic phase was modified to disperse spherical structure using rare earth metal halides. The corrosion rate and pitting behavior of modified and unmodified alloy were evaluated in 3.5% NaCl solution by general corrosion for calculated time. It was observed that the corrosion rate and pitting tendency of modified alloy had been appreciably reduced as compare to unmodified alloy. The improvement of corrosion properties were the attributes of changed morphology and distribution of Si rich eutectic phase.

scholarly journals THE EFFECT OF ELECTRIC FLOW ON DECORATIVE KROM ELECTROPLATING WITH COPPER BASE METAL TOWARD CORROSION RATE

2013 ◽  
Vol 1 (2) ◽  
pp. 134
Author(s):  
Ahmadi Ahmadi ◽  
Citra Ayu Dewi
Keyword(s):  
Corrosion Rate ◽  
Electric Current ◽  
Base Metal ◽  
Copper Metal ◽  
Chemical Laboratory ◽  
Copper Base ◽  
Metal Metal ◽  
One Year ◽  
Electroplating Process ◽  
Chrome Electroplating

In this study a decorative chrome electroplating process has been carried out with a copper base metal, metal electroplating is often used as a means to provide a thin layer on the surface of other metals or substrates using metal which has advantages in terms of property and corrosion resistance. In decorative chrome electroplating nickel and chrome are used as coatings, nickel and chrome are used as coatings because of their protective and decorative properties, protective means they can prevent corrosion and decorative because they look shiny so they look attractive. Copper metal is chosen because of its huge application in the community. This study aims to measure the corrosion rate in copper metal after a decorative chrome electroplating process based on electric current used during the electroplating process. This research is important because during the electroplating process a decorative chrome electoplating technique will be obtained in the form of modules, and the module will be used to train students to increase their skills. This research was conducted in the IKIP Mataram chemical laboratory with a time of one year. The process carried out in this study sequentially is to prepare an electrolyte solution used for electroplating, preparing the copper base metal to be free of oxide or rust, nickel coating and finally coating with chrome. From the coating process carried out then the results will be analyzed the corrosion rate by immersion in NaCl solution at a concentration of 36.05 grams / L for 336 hours, based on variations in electric current used during the electroplating process of 0.5; 1; 1.5; 2; and 2.5 Ampere, the corrosion rate results were 0.029; 0.013; 0.017; 0.022; and 0.012 mm / yr; while the copper metal which is not coated with a corrosion rate is 0.308 mm / yr. Thus it can be concluded that copper metal coated with nickel chrome will effectively resist the lowest rate of corrosion in the current given 2.5 Ampere.

Measurement and evaluation of galvanic corrosion between titanium/Ti6Al4V implants and dental alloys by electrochemical techniques and auger spectrometry

Biomaterials ◽  
1999 ◽  
Vol 20 (10) ◽  
pp. 933-941 ◽  
Author(s):  
Brigitte Grosgogeat ◽  
Lucien Reclaru ◽  
Michele Lissac ◽  
Francis Dalard
Keyword(s):  
Galvanic Corrosion ◽  
Electrochemical Techniques ◽  
Dental Alloys ◽  
Auger Spectrometry ◽  
Measurement And Evaluation
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