Improvement of corrosion resistance in steels for automotive and marine systems using ceramic coating by HVOF technique: A review

2022 ◽  
Author(s):  
Abhijeeth Nagaraj ◽  
H. Adarsha
Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 789 ◽  
Author(s):  
Farzad Soleymani ◽  
Rahmatollah Emadi ◽  
Sorour Sadeghzade ◽  
Fariborz Tavangarian

Magnesium alloys have received a great amount of attention regarding being used in biomedical applications; however, they show high degradability, poor bioactivity, and biocompatibility. To improve these properties, surface modification and various types of coatings have been applied. In this study, an anodized AZ91 alloy was coated with a polymer matrix composite made of polycaprolactone/chitosan (PCL/Ch) with different percentages of baghdadite to improve its resistance to corrosion, bioactivity, and biocompatibility. The effects of different percentages of baghdadite (0 wt %, 1 wt %, 3 wt %, and 5 wt %) on the surface microstructure, corrosion resistance, roughness, and wettability were evaluated. The results indicated that the applied nano-polymer-ceramic coating including 3 wt % baghdadite was hydrophobic, which consequently increased the corrosion resistance and decreased the corrosion current density of the anodized AZ91 alloy. Coating with 3 wt % baghdadite increased the roughness of AZ91 from 0.329 ± 0.02 to 7.026 ± 0.31 μm. After applying the polymer-ceramic coating on the surface of anodized AZ91, the corrosion products changed into calcium–phosphate compounds instead of Mg(OH)2, which is more stable in a physiological environment.


Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 993
Author(s):  
Alexander Sobolev ◽  
Tamar Peretz ◽  
Konstantin Borodianskiy

The fabrication of a ceramic coating on the metallic substrate is usually applied to achieve the improved performance of the material. Plasma electrolytic oxidation (PEO) is one of the most promising methods to reach this performance, mostly wear and corrosion resistance. Traditional PEO is carried out in an aqueous electrolyte. However, the current work showed the fabrication and characterization of a ceramic coating using PEO in molten salt which was used to avoid disadvantages in system heating-up and the formation of undesired elements in the coating. Aluminum 7075 alloy was subjected to the surface treatment using PEO in molten nitrate salt. Various current frequencies were applied in the process. Coating investigations revealed its surface porous structure and the presence of two oxide layers, α-Al2O3 and γ-Al2O3. Microhardness measurements and chemical and phase examinations confirmed these results. Potentiodynamic polarization tests and electrochemical impedance spectroscopy revealed the greater corrosion resistance for the coated alloy. Moreover, the corrosion resistance was increased with the current frequency of the PEO process.


2014 ◽  
Vol 960-961 ◽  
pp. 143-147
Author(s):  
Jun Zhao ◽  
Jian Jun Xi ◽  
Zhi Gang Wang ◽  
Chun Ping Zhao

Ceramic coatings were prepared on ZM5 magnetism substrate by micro-arc oxidation method with and without magnetism filed in silicate electrolyte. The morphology of the MAO coatings was investigated by scanning electron microscope (SEM). The friction coefficient of the MAO coatings prepared with magnetism is about 0.2 and more stable than the coatings prepared without magnetism. The polarization test indicated that the coating prepared with magnetism has better corrosion resistance.


2005 ◽  
Vol 200 (7) ◽  
pp. 2445-2450 ◽  
Author(s):  
Zhongping Yao ◽  
Zhaohua Jiang ◽  
Xiaohong Wu ◽  
Xuetong Sun ◽  
Zhendong Wu

2007 ◽  
Vol 353-358 ◽  
pp. 1733-1736 ◽  
Author(s):  
Fei Chen ◽  
Hai Zhou ◽  
Chen Chen ◽  
Fan Xiu Lu ◽  
Fan Xiu Lu

Oxidation ceramic coating was directly synthesized on LY12 aluminium alloy by micro-arc oxidation (MAO) process in Na2SiO3 electrolyte solution with the Na2WO4-KOH-Na2EDTA addition. The corrosion resistance of the coating was tested using CS300P electrochemical corrosion workshop in 3.5% NaCl solution. Using the scanning electron microscopy (SEM) and X-ray diffraction (XRD), the cross-section microstructure, the surface morphology and the phase structure of the micro-arc oxidation ceramic coating were analyzed. The results showed that the corrosion resistance of the micro-arc oxidation ceramic coating in 3.5% NaCl solution was enhanced remarkably, the corrosion velocity was obviously slowed down. The thickness of micro-arc oxidation ceramic coating was about 11μm. The final phases in the coating were found to be α-Al2O3 and γ-Al2O3. The mechanism of the oxidation ceramic coating formation was investigated too.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Qun Ma ◽  
Ping Wang ◽  
Xiaomin Chen ◽  
Chunqing Zhang

Abstract Plasma electrolytic oxidation (PEO) ceramic coating modified by carbon nanotubes (CNTs) was prepared on Mg–Gd–Y alloy. The microstructure, hydrophobicity and corrosion resistance of the coating were investigated by SEM, contact angle meter and electrochemical test system. Carbon nanotubes (CNTs) are staggered in the ceramic coating and partially filled with plasma discharge micropores. To some extent, CNTs can promote the plasma discharge and improve the film formation rate. With the increase of the content of CNTs, the content of carbon nanotubes in the ceramic coating increases. CNTs can effectively improve the hydrophobicity of ceramic coating. With the increase of the content of CNTs, the corrosion potential E coor and polarization resistance R p increase, the corrosion current i coor decreases and the AC impedance |Z| increases, which leads to the decrease of corrosion rate.


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