Volume 15, Issue 1 (6-2025)
مهندسی خوردگی 2025, 15(1): 60-60 |
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Improving the Adhesion and Resistance to Erosion Corrosion of Electroless Nickel-Phosphorus Coating Applied on Ductile Cast Iron Using Nickel Intermediate Layer. مهندسی خوردگی 2025; 15 (1) :60-60
URL: http://journal.ica.ir/article-1-246-en.html
URL: http://journal.ica.ir/article-1-246-en.html
Abstract: (2 Views)
Electroless nickel-phosphorus coatings are widely used in industries due to their excellent corrosion
and wear resistance. These coatings are applied on various substrates, but the coating applied on parts
made of cast iron does not have good adhesion due to the presence of graphite in their structure, and
cast irons are usually not coated by this method. This research aims to provide a solution to improve
the adhesion of electroless nickel-phosphorus coating to the ductile cast iron substrate with spherical
graphite. For this purpose, the surface of GGG50 cast iron was coated using an intermediate layer of
nickel applied by electroplating, and the electroless coating was deposited on this intermediate layer.
Different microscopic methods were used to examine the applied coating, and its adhesion was tested
according to the ISO 2819 standard. Also, the corrosion resistance of the coating in different thicknesses
was examined by Tafel polarization tests and electrochemical impedance spectroscopy, which revealed
that the coating with a thickness of 48 microns had a corrosion rate of 0.4 mpy which was the lowest
corrosion rate and 13 times more resistant than uncoated cast iron. Also, the erosion-corrosion test was
performed using the slurry pot method for 16 hours on this coating and the substrate. In this test, there
was no separation of the coating, and the degradation rate of the coating was 8.15 mpy, which,
compared to uncoated cast iron with a degradation rate of mpy 381, had a 46-fold improvement.
and wear resistance. These coatings are applied on various substrates, but the coating applied on parts
made of cast iron does not have good adhesion due to the presence of graphite in their structure, and
cast irons are usually not coated by this method. This research aims to provide a solution to improve
the adhesion of electroless nickel-phosphorus coating to the ductile cast iron substrate with spherical
graphite. For this purpose, the surface of GGG50 cast iron was coated using an intermediate layer of
nickel applied by electroplating, and the electroless coating was deposited on this intermediate layer.
Different microscopic methods were used to examine the applied coating, and its adhesion was tested
according to the ISO 2819 standard. Also, the corrosion resistance of the coating in different thicknesses
was examined by Tafel polarization tests and electrochemical impedance spectroscopy, which revealed
that the coating with a thickness of 48 microns had a corrosion rate of 0.4 mpy which was the lowest
corrosion rate and 13 times more resistant than uncoated cast iron. Also, the erosion-corrosion test was
performed using the slurry pot method for 16 hours on this coating and the substrate. In this test, there
was no separation of the coating, and the degradation rate of the coating was 8.15 mpy, which,
compared to uncoated cast iron with a degradation rate of mpy 381, had a 46-fold improvement.
Keywords: Corrosion, Electroless nickel – phosphorous, Electrochemical impedance spectroscopy, Erosion corrosion, Ductile cast iron.
Type of Study: Research |
Subject:
General
Received: 2026/01/27 | Accepted: 2025/06/15 | Published: 2025/06/15
Received: 2026/01/27 | Accepted: 2025/06/15 | Published: 2025/06/15
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