Corrosion Resistance of Unsealed Plasma Sprayed Coating Under Two Different Accelerated Exposures

2021 ◽  
pp. 173-176
Author(s):  
Yong Teck Tan ◽  
Poh Koon Aw
Keyword(s):  
Corrosion Resistance ◽  
Sprayed Coating ◽  
Plasma Sprayed

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 Effects of Selective Laser Modification and Al Deposition on the Hot Corrosion Resistance of Ceria and Yttria-Stabilized Zirconia Thermal Barrier Coatings

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 353 ◽  
Author(s):  
Panpan Zhang ◽  
Xiaofeng Zhang ◽  
Fuhai Li ◽  
Zhihui Zhang ◽  
Hong Li ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Hot Corrosion ◽  
Molten Salts ◽  
Yttria Stabilized Zirconia ◽  
Air Plasma ◽  
Laser Remelting ◽  
Stabilized Zirconia ◽  
Α Al2o3 ◽  
Sprayed Coating ◽  
Plasma Sprayed

The air-plasma-sprayed ceria and yttria-stabilized zirconia (CYSZ) coating was modified by selective laser remelting and Al deposition to enhance hot corrosion resistance. The dotted coating was obtained after selective laser remelting. Magnetron sputtering was used to deposit an Al film on the dotted coating, and a vacuum heat treatment was subsequently performed to produce a dense α-Al2O3 overlay. Hot corrosion behavior of the following three types of coatings was investigated: plasma-sprayed, dotted, and dotted coatings combined with Al deposition (DA). Hot corrosion behaviors were evaluated in a mixture of 55 wt % V2O5 and 45 wt % Na2SO4 molten salts at 1000 °C for 30 h. The hot corrosion reaction between molten salts and zirconia stabilizers (Y2O3 and CeO2) led to the generation of monoclinic zirconia, YVO4, and CeVO4 plate-shaped crystals, and the mineralization of CeO2. The results indicated that the hot corrosion resistance of the DA coating was the best, and the dotted coating had superior hot corrosion resistance in comparison with the plasma-sprayed coating. The minimal surface roughness and dense dotted units improved the hot corrosion resistance of the dotted coating. The dense α-Al2O3 overlay with chemical inertness effectively inhibited the infiltration of molten salts, which led to the optimal hot corrosion resistance of the DA coating.

Microstructure and Corrosion Resistance of Plasma Sprayed Fe-Based Alloy Coating as an Alternative to Hard Chromium

2010 ◽  
Vol 20 (5) ◽  
pp. 1063-1070 ◽  
Author(s):  
Wenhuan Lu ◽  
Yuping Wu ◽  
Jingjing Zhang ◽  
Sheng Hong ◽  
Jianfeng Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Alloy Coating ◽  
Hard Chromium ◽  
Plasma Sprayed

Laser Sintering of Nano-Al2O3 Powders on Plasma Sprayed Ceramic Based Coatings

2007 ◽  
Author(s):  
Lida Shen ◽  
Yinhui Huang ◽  
Zongjun Tian ◽  
Guoran Hua
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Plasma Spraying ◽  
Bond Coat ◽  
Continuous Wave ◽  
Ceramic Coatings ◽  
Laser Sintering ◽  
Al2o3 Ceramic ◽  
Plasma Sprayed ◽  
Steel Substrates

This paper describes an investigation of nano-Al2O3 powders reinforced ceramic coatings, which has included NiCrAl and Al2O3+13%wt.TiO2 coats pre-produced by atmosphere plasma spraying, implemented by laser sintering. Commercial NiCrAl powders were plasma sprayed onto 45 Steel substrates to give a bond coat with thickness of ∼100μm. The 600μm thick Al2O3+13%wt.TiO2 based coating was also plasma sprayed on top of the NiCrAl bond coat. With 2.5kw continuous wave CO2 laser, nano-Al2O3 ceramic powders were laser sintered on the based Coatings. The micro structure and chemical composition of the modified Al2O3+13%wt.TiO2 coatings were analyzed by such detection devices as scanning electronic microscope (SEM) and x-ray diffraction (XRD). Microhardness, wear resistance and corrosion resistance of the modified coatings were also tested and compared with that of the unmodified. The results show that the crystal grain size of Al2O3 had no obvious growth. In addition, due to the nanostructured Al2O3 ceramic phases, the coatings exhibited higher microhardness, better wear resistance and corrosion resistance than those unmodified counterparts. The complex process of plasma spraying with laser sintering as a potential effective way of the application of ceramic nano materials was also simply discussed and summarized in the end.

Investigations of the Fracture of Composites Matrix-Coating Under Tension

1998 ◽  
Author(s):  
V.E. Panin ◽  
V.A. Klimenov ◽  
S.V. Panin
Keyword(s):  
Steel Matrix ◽  
Matrix Composites ◽  
Coating Quality ◽  
Deformation Stages ◽  
The Matrix ◽  
Sprayed Coating ◽  
Plasma Sprayed

Abstract Deformation stages and specific features were studied by mesomechanical methods under tension of plasma sprayed coating-steel matrix composites. The effect of coating quality on the deformation of the matrix at the mesolevel was revealed. The results obtained make it possible to predict reliability and durability of this kind of coating and of the entire composite.

scholarly journals Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings

2015 ◽  
Vol 9 (1) ◽  
pp. 42-55 ◽  
Author(s):  
Imane Demnati ◽  
David Grossin ◽  
Olivier Marsan ◽  
Ghislaine Bertrand ◽  
Gérard Collonges ◽  
...  
Keyword(s):  
Side Reaction ◽  
Processing Parameters ◽  
X Ray Diffraction ◽  
Unexpected Formation ◽  
Monoclinic Form ◽  
Ion Exchange Reaction ◽  
Physical Chemical ◽  
Distribution Mapping ◽  
Sprayed Coating ◽  
Plasma Sprayed

Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities.

scholarly journals Transient Phenomena in Plasma Torches and in Plasma Sprayed Coating Generation

1997 ◽  
Vol 07 (C4) ◽  
pp. C4-187-C4-198 ◽  
Author(s):  
P. Fauchais ◽  
J. F. Coudert ◽  
M. Vardelle
Keyword(s):  
Transient Phenomena ◽  
Plasma Torches ◽  
Sprayed Coating ◽  
Plasma Sprayed
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