Sealing Treatment of Plasma Sprayed Cr3C2-NiCr/Al2O3-TiO2 Coating by Aluminum Phosphate Sealant Containing Al2O3 Nanoparticles

2021 ◽  
Author(s):  
Tuan Nguyen Van ◽  
Tuan Anh Nguyen ◽  
Ha Pham Thi ◽  
Ly Pham Thi ◽  
Phuong Nguyen ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Aluminum Phosphate ◽  
Al2o3 Nanoparticles ◽  
Treatment Efficiency ◽  
Typical Structure ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Sealing Treatment ◽  
Sprayed Coatings

Abstract A typical structure of thermal spray coatings consisted of molten particles, semi-molten particles, oxides, pores and cracks. These factors caused the porosity of sprayed coatings, leading to a great influence on the coating properties, especially their wear-corrosion resistance. In this study, a post-spray sealing treatment of Cr3C2-NiCr/Al2O3-TiO2 plasma sprayed coatings was carried out, then their corrosion properties were evaluated, before and after the treatment. For sealing process, aluminum phosphate (APP) containing aluminum oxide (Al2O3) nanoparticles (~10 nm) was used. The permeability of APP into the sprayed coating was analyzed by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The treatment efficiency for porosity and corrosion resistance of sprayed coatings were evaluated by electrochemical measurements, such as the potentiodynamic polarization and electrochemical impedance spectroscopy. In addition, the wear-corrosion resistance of the sealed coating was examined in 3.5 wt.% NaCl circulation solution containing 0.25 wt.% SiO2 particles. The obtained results showed that APP penetrated deeply through the sprayed coating. The incorporation of Al2O3 nanoparticles into APP sealant enhanced the treatment efficiency of porosity for sprayed coating. The effect of the post-treatment on corrosion protection of the sprayed coating has been discussed.

scholarly journals Sealing Treatment of Plasma-Sprayed Cr3C2-NiCr/Al2O3-TiO2 Coating by Aluminum Phosphate Sealant Containing Al2O3 Nanoparticles

2021 ◽  
Author(s):  
Tuan Van Nguyen ◽  
Tuan Anh Nguyen ◽  
Ha Thi Pham ◽  
Ly Thi Pham ◽  
Phuong Thi Nguyen ◽  
...  
Keyword(s):  
Aluminum Phosphate ◽  
Tio2 Coating ◽  
Al2o3 Nanoparticles ◽  
Plasma Sprayed ◽  
Sealing Treatment

Influence of Ultrasonic Sealing Treatment with Aluminum Phosphate on Properties of Al2O3-TiO2 Plasma Sprayed Ceramic Coating

2021 ◽  
Author(s):  
Tuan Nguyen Van ◽  
Tuan Anh Nguyen ◽  
Phuong Nguyen Thi ◽  
Ha Pham Thi ◽  
Ly Pham Thi ◽  
...  
Keyword(s):  
Ceramic Coating ◽  
Erosion Resistance ◽  
Electrochemical Impedance ◽  
Aluminum Phosphate ◽  
Ceramic Coatings ◽  
Corrosion And Wear ◽  
Tio2 Ceramic ◽  
Plasma Sprayed ◽  
Sealing Treatment ◽  
Thermally Sprayed

Abstract Thermally sprayed Al2O3-TiO2 ceramic coatings provide exceptional hardness and corrosion and wear resistance, but the high velocities at which they are applied result in an inherently porous structure that requires some type of remediation. This study evaluates the effectiveness of ultrasonic aluminum phosphate sealing treatments on plasma sprayed Al2O3-40TiO2 ceramic coatings. The sealants were applied with and without ultrasonication (20-40 kHz) and were assessed using SEM/EDX analysis, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Test data indicate that optimum sealing, corresponding to the highest values of corrosion protection and erosion resistance, are achieved under ultrasonication at 30 kHz for 5 hours.

scholarly journals EIS and corrosion behaviour of plasma sprayed layers of Al and AlCr6Fe2 on AZ91

2018 ◽  
Vol 62 (2) ◽  
pp. 33-44
Author(s):  
F. T. Kubatík ◽  
J. Stoulil ◽  
F. Lukáč ◽  
K. Stehlíková ◽  
P. Slepička
Keyword(s):  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Intermetallic Phase ◽  
Fold Increase ◽  
Eutectic Structure ◽  
Metallurgical Bonding ◽  
Magnesium Alloy Az91 ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Abstract This work presents the preparation of coatings of aluminium and AlCr6Fe2 alloy on magnesium alloy AZ91 with metallurgical bonding. Coatings were prepared by plasma spraying system WSP®-H 500. This metallurgical bond (sub-layer) is formed by an eutectic structure consisting of the intermetallic phase Mg17Al12 and the solid solution of magnesium and aluminium. In this work, the layers were studied using electrochemical impedance spectroscopy (EIS). It was shown that there is a several fold increase of the polarization resistance (Rcν) of plasma-sprayed coatings of aluminium and AlCr6Fe2 alloy, compared with uncoated AZ91 in borate buffer with pH 9.1.

Residual Stress Measurement of Plasma Sprayed Coating Layers in ZrO2

2007 ◽  
Vol 544-545 ◽  
pp. 451-454
Author(s):  
Soo Wohn Lee ◽  
Jia Zhang ◽  
Huang Chen ◽  
J. S. Song ◽  
Jae Kyo Seo ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Diffraction Method ◽  
Spray Coating ◽  
X Ray Diffraction ◽  
Plasma Sprayed Coatings ◽  
Coating Layers ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Plasma sprayed coatings have been widely applied in modifying surface properties of metal components. It is also useful to prevent various types of wear, corrosion, erosion and thermal. But the residual stress is still an important problem which can effect the properties of sprayed coating. So it’s necessary to find out the reason of residual stress and the relationship between plasma sprayed condition and residual stress. Plasma spray coating layers with conventional ZrO2 powder was examined to calculate residual stress by X-ray diffraction method with various coating thickness.

New Challenge of Plasma Spray Coatings in Nano Oxide Ceramics

2006 ◽  
Vol 317-318 ◽  
pp. 533-538
Author(s):  
Soo Wohn Lee ◽  
Huang Chen ◽  
Yi Zeng ◽  
Chuan Xian Ding
Keyword(s):  
Electron Microscopy ◽  
Deposition Efficiency ◽  
Metallic Substrate ◽  
Atmospheric Plasma ◽  
Ceramic Powders ◽  
Plasma Sprayed Coatings ◽  
Coating Layers ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Nanostructured and conventional Al2O3, ZrO2, and TiO2 were deposited using an atmospheric plasma spraying (APS). The size of commercial nano-ceramic powders was varied from 5nm up to 150nm. The microstructure and phase composition of the plasma sprayed coatings on metallic substrate were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was found that nano-sized ceramic powders enhanced the deposition efficiency on the metallic substrate rather than the micro-sized conventional commercial powders. Density and mechanical property such as microhardness were better in the case of the nano-sized ceramic powders than that of the conventional micro-sized ceramic powders, which are associated with the fine surface roughness and less size in pores of the coating layers. The wear rate of the nanostructured coating was lower than that of the conventional coating. The results were explained in terms of their microstructure of the coatings layers. Also, photocatalytic characterization of the plasma sprayed coatings, using nanocrystalline size TiO2 as feedstock with various powder sizes and shapes as well as adding with different photocatalytic oxides, was performed. The photocatalytic reactivity using plasma sprayed coating layers can be utilized into various applications.

Effect of Sealing Treatment on Corrosion Resistance of Plasma-Sprayed NiCrAl/Cr2O3-8 wt.%TiO2 Coating

2010 ◽  
Vol 20 (3) ◽  
pp. 508-513 ◽  
Author(s):  
Jingjing Zhang ◽  
Zehua Wang ◽  
Pinghua Lin ◽  
Wenhuan Lu ◽  
Zehua Zhou ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Tio2 Coating ◽  
Plasma Sprayed ◽  
Sealing Treatment

scholarly journals Porosity and Its Significance in Plasma-Sprayed Coatings

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 460 ◽  
Author(s):  
John Gerald Odhiambo ◽  
WenGe Li ◽  
YuanTao Zhao ◽  
ChengLong Li
Keyword(s):  
Working Environment ◽  
Atmospheric Plasma ◽  
Formation Mechanisms ◽  
Multilayer Coatings ◽  
Oxide Coatings ◽  
Spraying Parameters ◽  
Plasma Sprayed Coatings ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Porosity in plasma-sprayed coatings is vital for most engineering applications. Porosity has its merits and demerits depending on the functionality of the coating and the immediate working environment. Consequently, the formation mechanisms and development of porosity have been extensively explored to find out modes of controlling porosity in plasma-sprayed coatings. In this work, a comprehensive review of porosity on plasma-sprayed coatings is established. The formation and development of porosity on plasma-sprayed coatings are governed by set spraying parameters. Optimized set spraying parameters have been used to achieve the most favorable coatings with minimum defects. Even with the optimized set spraying parameters, defects like porosity still occur. Here, we discuss other ways that can be used to control porosity in plasma-sprayed coating with emphasis to atmospheric plasma-sprayed chromium oxide coatings. Techniques like multilayer coatings, nanostructured coatings, doping with rare earth elements, laser surface re-melting and a combination of the above methods have been suggested in adjusting porosity. The influences of porosity on microstructure, properties of plasma-sprayed coatings and the measurement methods of porosity have also been reviewed.

scholarly journals Influence of Ultrasonic Excitation Sealing on the Corrosion Resistance of HVOF-Sprayed Nanostructured WC-CoCr Coatings under Different Corrosive Environments

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 724 ◽  
Author(s):  
Zhang ◽  
Hong ◽  
Lin ◽  
Zheng
Keyword(s):  
Corrosion Resistance ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Aluminum Phosphate ◽  
Open Circuit ◽  
Corrosive Environments ◽  
Oxygen Fuel

The corrosion behavior of unsealed and sealed high-velocity oxygen-fuel (HVOF)-sprayed nanostructured WC-CoCr cermet coatings under different corrosive environments was investigated using scanning electron microscopy (SEM), open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Ultrasonic excitation sealing with aluminum phosphate was performed in an external ultrasonic bath with the frequency of 40 kHz at atmospheric pressure and room temperature. SEM micrographs revealed that the exposed area of the coating was effectively reduced by the coverage of aluminum phosphate sealant on the majority of pores. Electrochemical measurements demonstrated that the sealant with the help of ultrasonic energy could shift the corrosion potential to a more noble direction, reduce the corrosion current density, increase the resistance of charge transfer, and effectively improve the corrosion resistance of the coating in both 3.5 wt % NaCl and 1 mol·L−1 HCl solutions.

Effect of Sealing Treatment of Modified Aluminum Phosphate Sealing Agent on Corrosion Resistance of Fe-Based Amorphous Coating

2022 ◽  
Vol 905 ◽  
pp. 61-66
Author(s):  
Cheng Fei Li ◽  
Xiao Jun Yang ◽  
Ding Yong He
Keyword(s):  
Corrosion Resistance ◽  
Heat Resistance ◽  
Raw Materials ◽  
Aluminum Phosphate ◽  
Dihydrogen Phosphate ◽  
Amorphous Coating ◽  
Before And After ◽  
Sealing Treatment ◽  
Good Heat Resistance ◽  
Sealing Layer

A modified aluminum phosphate sealing agent was prepared by using aluminum dihydrogen phosphate and silica sol as raw materials, and was used for sealing treatment of iron-based amorphous coating. The phase of sealing agent was analyzed by XRD. SEM and TG-DSC were used to characterize the surface morphology of the coating before and after sealing and the heat resistance of the sealing agent. The corrosion resistance of the sealing coating was evaluated by electrochemical measurements. The results show that the modified aluminum phosphate sealing agent has good heat resistance, and fine and close sealing layer was obtained, thus the corrosion resistance is significantly improved.

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