Dezincification Corrosion Research Articles

(Invited) In-situ Evaluation of Brass Dezincification Corrosion Under Galvanostatic Polarization Combined with Video Observation

Brass is widely used as the applications involving water supply pipes and pipe heat exchangers owing to its good mechanical properties. One of the limiting factors for use of brass is the dezincification corrosion, which may cause the water leakage accident. In the dezincification corrosion, the selective dissolution of zinctakes place on the brass surface, and the porous copper rich layer is formed on the brass surface1,2. To clarify the dezincification corrosion behavior of brass, we have newly developed a real-time cross-sectional surface observation system to examine the dezincification corrosion behavior of brass6. Our group developed a real-time surface observation system combined with video imaging to investigate the dissolution behavior of metals3-5. Comparing to the previous works3-5, the developed system in the present study allows for an in-situ monitoring of metal or alloy cross-section during electrochemical measurement because the video of metal or alloy cross-section can be taken by an optical microscope combined with a charge-coupled device camera. We applied the developed method for the investigation of brass dezincification corrosion, demonstrating that the inhomogeneous dissolution was observed in the depth direction under galvanostatic polarization. The average erosion depth could be estimated from the cross-sectional surface images at each measurement time. The results indicated that the depth erosion rate was different at initial and later stages, implying the preferential dissolution of zinc or the simultaneous dissolution of zinc and copper on the brass surface. Based on the video images and potential changes of brass during the measurement, the detailed dissolution behavior was discussed in the present study.References H.W. Pickering, C. Wagner, J. Electrochem. Soc., 7, 114 (1967). Y. Hoshi et al., J Solid State Electrochem, 19, 3551 (2015). Y. Hoshi et al., J. Electrochem. Soc., 164, C450 (2017). Y. Hoshi et al., Surf. Finish. Soc. Jpn., 69, 34 (2018). Y. Hoshi et al., J. Electrochem. Soc., 165, C243 (2018).Y. Hoshi et al., Mater. Trans., 64, 885 (2023).

Real-Time Imaging of Brass Cross-Section with Dezincification Corrosion by Electrochemical Measurement Combined with Video Observation

A real-time imaging electrochemical measurement system was developed for an in-situ observation of brass dezincification corrosion. This system allows for a video recording of brass cross-section under galvanostatic polarization. The progress of erosion associated with the dezincification corrosion in the depth direction on the brass cross-section was successfully observed from the video recording during the measurement. The erosion depth at each measurement time could be estimated from the cross-section images, indicating that the erosion depth was drastically increased at arbitrary time under galvanostatic polarization. It suggested that the erosion rate in the depth direction is strongly related to the dissolution behavior of zinc and copper from brass surface, namely, the preferential dissolution and the simultaneous dissolution. The relation between the dissolution behavior and the electrode potential of brass under galvanostatic polarization was discussed.

Cause Analysis of Tube Burst of the Condenser in a Power Plant

A tube burst accident of the condenser is found in a power plant during operation. The causes of tube bursts are analyzed using macroscopic observation, chemical composition analysis, metallographic examination, scanning electron microscopy, and energy spectrum. The results show that the perforation of the condenser tube originates from the inner wall, and there are scour pits. There are corrosion products in the pits, and the content of the Zn element decreases significantly compared with the matrix. The corrosion should be dezincification corrosion accompanied by erosion corrosion. After the long-term operation of the condenser pipe, dezincification corrosion is still unavoidable. Pipes in different parts have been corroded and perforated, but the degree of corrosion is different. Therefore, it is suggested to replace and upgrade the condenser tube as a whole at the appropriate time.

Real-Time Imaging of Brass Cross-Section to Investigate Dezincification Corrosion Behavior during Electrochemical Measurement

The dezincification corrosion is a major limiting factor for use of brass in the plumbing system as it may cause the water leakage accident. It is well known that the porous copper rich layer is formed on the brass surface due to the dezincification corrosion, namely, the selective dissolution of zincoccurs on the brass surface1,2. We have developed the real-time surface observation system with channel flow double electrode to examine the dissolution behavior of copper and magnesium3-5. In the present study, a real-time cross-sectional surface observation system was developed to investigate the dezincification corrosion behavior of brass during electrochemical measurement.An electrochemical cell was made using transparent acrylic plates. An electrochemical measurement was performed by a three-electrode system. The brass plate and the platinum wire were used as the working electrode and the counter electrode, respectively. A KCl-saturated silver/silver chloride electrode was used as the reference electrode. The electrolyte solution was 0.5 M NaCl containing 5 mM NaHCO3. The temperature of electrolyte solution was kept at 60 oC. The brass plate was fixed at wall surface of the electrochemical cell to record the video of the brass cross-section.The video of the brass cross-section was taken by an optical microscope combined with a charge-coupled device camera under the galvanostatic polarization for 24 h. The brass cross-section under the galvanostatic polarization was successfully observed from the video recording, indicating that the dissolution of brass progressed inhomogeneously in the depth direction. We estimated the erosion depth from the cross-sectional surface images at each measurement time. The results demonstrated that the erosion depth was increased with time under galvanostatic polarization. The dissolution process involving preferential dissolution of zinc or the simultaneous dissolution of zinc and copper was discussed based on the video images and the potential changes of brass during the measurement.

Real–Time Imaging of Brass Cross–Section with Dezincification Corrosion by Electrochemical Measurement Combined with Video Observation

Real–Time Imaging of Brass Cross–Section with Dezincification Corrosion by Electrochemical Measurement Combined with Video Observation

WIELAND C23000

Abstract Wieland C23000 (C230), also known as red brass, is an 85Cu-15Zn alloy. The alloy has excellent cold forming properties and is generally not susceptible to dezincification and stress corrosion. Due to this combination of properties and its attractive color, the alloy is used for decorative purposes as well as for a wide variety of drawn and formed parts. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as heat treating. Filing Code: Cu-925. Producer or source: Wieland Rolled Products NA.

Corrosion Behavior of Brass H62 in Harsh Marine Atmosphere in Nansha Islands, China

The corrosion behavior of brass H62 exposed to the atmosphere of Nansha Islands for 21 months was investigated by weight loss, scanning electron microscopy, x-ray diffraction and electrochemical techniques. The results showed that the average corrosion rate of brass H62 exposed for 1 year was approximately 13.47 g m−2 a−1, and the corrosion products were observed to be unevenly distributed, attributed to the dezincification corrosion. In addition to the zinc-containing compounds Zn5(OH)8Cl2·H2O and NaZn4(SO4)Cl(OH)6·6H2O, the copper-containing compounds Cu2O and Cu2Cl(OH)3 were also detected on the front side of the exposed sample, while only the zinc-containing compounds were detected on the back side. Both sides of brass H62 showed a decreasing corrosion rate, but the corrosion product layer on the back side appeared to be more protective for the same exposure time.

Research and Application of Cleaning and Coating for Condenser

The scale on the water side of condenser copper pipe of unit 3 in a power plant has exceeded 1mm and “dezincification corrosion” has occurred. The condenser copper tubes were cleaned and coated by static and dynamic tests. After the completion of the project, the inner wall of the copper pipe is cleaned and the coating is in good condition, achieving the expected effect.

Development of A Method to Evaluate Dezincification Corrosion Depth of Brass by Impedance Analysis Using Transmission Line Model Involving CPE

Development of A Method to Evaluate Dezincification Corrosion Depth of Brass by Impedance Analysis Using Transmission Line Model Involving CPE

Corrosion failure analysis on the copper alloy flange by experimental and numerical simulation

This paper reports the failure analysis of a leaked copper flange used in diesel engine cooling system of a ship after less than one year of service. The failure flange was subjected to optical microscopy, and SEM, and corrosion product was analyzed by XPS. The failure cause is that polytetrafluoroethylene on the monel gasket can't go into to pores formed by dezincification corrosion inside copper alloy because of limited deformation of polytetrafluoroethylene. Then water will go through the continuous channels, causing leakage of the flange. Further, according to the results of electrochemical test, immersion test and numerical simulation, QAl10-3-1.5 aluminum bronze was recommended to replace the using flange, because no dezincification was observed and galvanic corrosion risk is small.

Real-Time Cross-Sectional Surface Observation of Brass to Investigate Dezincification Corrosion

The dezincification corrosion of brass (Cu-Zn alloy) is a serious problem in the plumbing system because it may cause the leakage accident. When the dezincification corrosion occurs on the brass surface, a porous copper rich layer is formed on the brass surface due to the selective dissolution of zinc1,2. In order to understand the dissolution mechanisms, it is important to explore the relationship between the dissolution behavior of zinc and the growth of the copper rich layer. Our group3-5 developed the real-time surface observation system with channel flow double electrode to investigate localized corrosion of copper and magnesium. In the present study, a real-time cross-sectional surface observation system combined with electrochemical measurement was developed for the investigation of the dezincification corrosion of brass. A video of the cross-sectional surface morphology of brass was taken by an optical microscope combined with a charge-coupled device (CCD) camera during the anodic polarization. The electrochemical cell was constructed using transparent acrylic plates. The electrochemical measurement was carried out by a three-electrode cell. The working electrode and the counter electrode were a brass plate and a platinum wire, respectively. A KCl-saturated silver/silver chloride electrode (SSE) was used as a reference electrode. The electrolyte solution was 0.5 M NaCl containing 5 mM NaHCO3 and kept at 60 oC. The surface of brass plate was covered with the transparent resin except the active surface area (0.393 cm2). The brass plate was fixed at wall surface to record the video of the active surface area. The galvanostatic polarization was performed for 24 h to observe the dissolution behavior of brass. After 3 hours, the copper rich layer was formed on the brass surface due to the selective dissolution of zinc. The localized dissolution was observed after 6 hours, and the dissolution was then observed on the whole surface. The selective dissolution of zinc and simultaneous dissolution of zinc and copper from brass surface were discussed based on the video images and the potential changes of brass during the measurement.

Corrosion behavior of copper T2 and brass H62 in simulated Nansha marine atmosphere

The accelerated corrosion behavior of copper T2 and brass H62 exposed in simulated Nansha marine atmosphere for different periods were investigated by weight loss method, SEM, XRD and potentiodynamic polarization measurements. The results indicate that copper T2 and brass H62 underwent severe corrosion, and the final corrosion rates at 32 days of exposure were 0.24 μm/d and 0.10 μm/d, respectively. Moreover, the overall corrosion type of copper T2 was uniform and the corrosion products Cu2O and Cu2Cl(OH)3 played a vital role in the corrosion rate of copper. While the dezincification corrosion with zinc preferential dissolution was obvious in brass H62. The predominant phases were the zinc-rich compounds Zn5(OH)8Cl2·H2O, Zn12(SO4)3Cl3(OH)15·5H2O and NaZn4(SO4)Cl(OH)6·6H2O. There existed a large number of copper-rich holes with 20–50 μm depth beneath the corrosion product layer.

A newly lead-free free-cutting as-hydrogenated titanium brass

A newly lead-free free-cutting as-hydrogenated titanium brass was prepared by the hydrogenation of titanium brass. The phase constitution of the as-hydrogenated titanium brass was examined by XRD, SEM and TEM. Relevant properties, including machinability, dezincification corrosion and mechanical properties, were characterized. An ordered FCC titanium hydride is observed in the titanium brass matrix after hydrogenation treatment. Compared with common brass, the as-hydrogenated titanium brass exhibits better machinability and dezincification corrosion properties. Therefore, this newly lead-free as-hydrogenated titanium brass can be applied as promising plumbing materials.

Failure Analysis on Leakage of Brass Condenser Tube in Thermal Power Plant

The corrosion failure analysis of the brass tube in a power plant condenser was conducted by the methods of chemical composition analysis, macro morphology inspection of the leakage point, metallurgical examination, scanning electron microscope and energy spectrum analysis etc. The results indicated that the failure of the brass tube was due to the erosion of the internal surface. The zinc content in the etching pits decreased obviously and dezincification corrosion could be classified. Some suggestions for anti-corrosion measures of the brass tubes were put forward.

Electrochemical Impedance Analysis on Dezincification Corrosion of Brass with Transmission Line Model

Brass (Cu-Zn alloy) is widely used in the plumbing systems because of its good mechanical properties and low cost. The dezincification corrosion of brass is major problem in the plumbing system because a porous copper rich layer is formed on the brass surface due to the selective dissolution of zinc [1, 2]. Thus, it is difficult to evaluate the corrosion conditions of brass. Hoshi et al. [3] applied an electrochemical impedance spectroscopy for the investigation of the dezincification corrosion of brass. They [3] reported that the distorted impedance is observed in the high frequency range on a Nyquist plane, which is associated with the current distribution on the porous copper rich layer formed on the brass surface. In the present study, a transmission line model (TLM) [4] involving a constant phase element (CPE) was applied to the analysis of the distorted impedance of brass in the high frequency range. The impedance of the brass with the different thickness of copper-rich layer on the brass surface was examined in order to develop the evaluation method for the dezincification corrosion of brass. A susceptibility test of dezincification corrosion of brass was carried out for 24, 36, 48, and 72 hour in order to form the copper-rich layer on the brass surface. The electrochemical impedance measurement of brass with different thickness of copper-rich layer was performed by a three-electrode system. The working electrode and the counter electrode were the brass with different thickness of copper-rich layer and a platinum wire, respectively. A KCl-saturated silver/silver chloride electrode (SSE) was used as a reference electrode. The electrolyte solution was 0.5 M NaCl containing 5 mM NaHCO3. The impedance spectrum was measured in the frequency range of 0.1 Hz – 10 kHz at five frequencies per decade with an AC amplitude of 10 mV. The applied DC potential was -0.10 V vs. SSE. After the measurement, the surface morphology of brass was investigated by a field emission scanning electron microscope (FE-SEM). The impedance spectra of brass with different thickness of copper-rich layer on the brass surface described the locus with small slope in the high frequency range. In this case, the locus shows the straight line whose slope is lower than 45◦ against real axis in the high frequency range. These results indicate that the value of the slope is related to the structures of copper-rich layer. We [3] derived the theoretical equation to determine the dezincification corrosion area of brass from the impedance at transition frequency. Although the distributed constant region and lumped constant region are observed in the impedance spectra, it is difficult to determine the impedance at transition frequency precisely from the plots of impedance in the present study. In order to determine the impedance at transition frequency, the impedance in the distributed constant region was analyzed by the TLM involving CPE and discussed by using CPE constant p. The differential values of impedance in the high frequency range and arbitrary value of p are discussed, and the impedance at transition frequency was determined from the impedance spectra of brass with different thickness of copper-rich layer.

Mn Bs C プロペラの脱亜鉛腐蝕と Zn との関係について

Mn Bs C プロペラの脱亜鉛腐蝕と Zn との関係について

Surface monitoring for pitting evolution into uniform corrosion on Cu-Ni-Zn ternary alloy in alkaline chloride solution: ex-situ LCM and in-situ SECM

The evolution of the corrosion process on Cu-Ni-Zn alloy in alkaline chloride solution was investigated by in-situ scanning electrochemical microscopy, X-ray photoelectron spectroscopy, and ex-situ laser confocal microscopy, and the effects of ambient temperature and polarization time were also discussed. The results demonstrated a higher pitting nucleation rate and lower pit growth rate at low temperature. The ratio of pit depth to mouth diameter decreased with increasing pit volume and temperature, indicating that pits preferentially propagate in the horizontal direction rather than the vertical direction owing to the presence of corrosion products and deposited copper. The surface current was uniform and stabilized at approximately 2.2 nA during the passive stage, whereas the current increased after the pits were formed with the maximum approaching 3 nA. Increasing the temperature led to an increase in porous corrosion products (CuO, Zn(OH)2, and Ni(OH)2) and significantly increased the rate of transition from pitting to uniform corrosion. Dezincification corrosion was detected by energy dispersive spectrometry, and a mechanism for pitting transition into uniform corrosion induced by dezincification at the grain boundaries is proposed.

Al<SUB>2</SUB>O<SUB>3</SUB> Nanoparticles Induced High Dezincification Corrosion Resistance of 71 wt.% Cu–Zn Alloy

Al<SUB>2</SUB>O<SUB>3</SUB> Nanoparticles Induced High Dezincification Corrosion Resistance of 71 wt.% Cu–Zn Alloy

Evaluation of Dezincification Corrosion of Brass By Complex Capacitance

An electrochemical impedance spectroscopy (EIS) was used in order to discuss the detailed dissolution mechanisms because the EIS enables us to discriminate the time constants of elementary steps in the dissolution process. The capacitive loop related to the electrode/solution interface is often observed in the impedance spectrum in the high frequency range when the metal is immersed in the electrolyte solution. Since the electric-double layer capacitance C dl is related to the surface area and structure of electrode/electrolyte interface, it is generally estimated by the curve fitting of the result of the impedance spectrum. Our group [1] previously reported the calculations of the electrochemical impedance and complex capacitance corresponding to typical equivalent circuits because the precise value of C dl could be estimated by the capacitance plot. The complex capacitance analysis was applied to the evaluation of the performance of energy conversion devices [2-5]. In the present study, the complex capacitance analysis was applied to evaluation of dezincification corrosion of brass. It is important to estimate the precise value of C dl because a porous Cu-enriched layer is formed on the brass surface due to the selective dissolution of Zn from brass surface [7]. The evaluation method of the dezincification of brass by capacitance plot was proposed.

Evaluation of Dezincification Corrosion of Brass By Electrochemical Impedance

The dezincification corrosion of the brass has been investigated to obtain the fundamental knowledge concerning the selective dissolution mechanisms. Pickering et al. (1-3) reported that a porous Cu-rich layer was formed on the brass surface due to the selective dissolution of Zn from brass. They classified the dissolution of the binary alloy into two types, which is the selective dissolution and simultaneous dissolution. In the present work, we investigated the dissolution of brass by an electrochemical impedance spectroscopy (EIS). The EIS enables us to discriminate the time constants of elementary steps in the dissolution process. The Cu-enriched layer was formed on the brass surface by following method: The galvanostatic polarization of the brass was performed at 1.0 mA/cm2 for 24 h in the electrolyte solution of 0.5M NaCl containing 5mM NaHCO3. The temperature of the electrolyte solution was keep at 60 oC by thermostatic bath. In order to investigate the porous structure of the Cu-enriched layer formed on the brass surface due to dezincing, the impedance spectrum was measured to examine the current distributions within the pores. In addition, impedance and complex capacitance corresponding to the typical equivalent circuits involving a transmission line model (TLM) are discussed to propose the evaluation method for the dezincification of brass. Reference 1. H. W. Pickering and C. Wagner, Journal of the Electrochemical Society, 114, 698 (1967).2. H. W. Pickering, Journal of the Electrochemical Society, 115, 143 (1968).3. H. W. Pickering and P. J. Byrne, Journal of the Electrochemical Society, 116, 1492 (1969).