Comparative study on corrosion behavior of plasma sprayed Al2O3, ZrO2, Al2O3/ZrO2 and ZrO2/Al2O3 coatings
01 May 2016-Transactions of Nonferrous Metals Society of China (Elsevier)-Vol. 26, Iss: 5, pp 1336-1344
TL;DR: In this paper, the microstructure and phase composition of the as-sprayed coatings were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively.
About: This article is published in Transactions of Nonferrous Metals Society of China.The article was published on 2016-05-01. It has received 28 citations till now. The article focuses on the topics: Conversion coating & Salt spray test.
Citations
More filters
TL;DR: In this article, phase composition, microstructure and mechanical properties of chromia and alumina composite coatings on carbon steel substrates were studied and compared to individual Cr2O3 and Al 2O3 coatings.
Abstract: In the present work, chromia and alumina coatings were produced by atmospheric plasma spray process. Phase composition, microstructure and mechanical properties of chromia and alumina composite coatings on carbon steel substrates were studied and compared to individual Cr2O3 and Al2O3 coatings. Morphology and microstructure of coatings were characterized using scanning electron microscopy equipped by EDS. The porosity of the plasma-sprayed coatings was measured by the Archimedes water immersion technique and image analysis method. X-ray diffraction was employed to identify phase composition of coatings. Also some mechanical properties such as bonding strength, Vickers microhardness and resistance to crack propagation of coatings were measured. The results showed different phases for Al2O3 in different coatings while Cr2O3 remained in eskolaite phase in all of the coatings. Addition of 75 wt% Cr2O3 prevented formation of metastable and undesirable γ-Al2O3 phase. Alumina and rich-alumina coatings showed denser microstructure and higher flattening degree of splats as well as lower surface roughness. Bonding strength of individual Cr2O3 and Al2O3 coatings was higher than composite one. Vickers microhardness increased with addition of Cr2O3. Alumina improved spray ability and crack propagation resistant of chromia.
62 citations
TL;DR: In this paper, the effects of alumina addition and annealing treatment on the microstructure and mechanical properties of the plasma sprayed Al2O3-YSZ composite coatings were investigated by XRD, SEM and an instrumented indentation testing system.
31 citations
TL;DR: In this article, the high temperature oxidation kinetics curves of the coating were examined; the bonding strength between the coatings and the metal substrates was studied; and analyses were conducted on the thermal shock resistance and the failure mechanism of the surface coatings.
Abstract: Al 2 O 3 non-gradient ceramic coating (marked as 1# coating) and NiCrAlY/Al 2 O 3 gradient ceramic coating (marked as 2# coating) were prepared with the plasma spraying and slurry spraying methods, respectively. The coating specimens were characterized by scanning electron microscopy and X-ray diffractometry. The high temperature oxidation kinetics curves of the coatings were examined; the bonding strength between the coatings and the metal substrates was studied, and analyses were conducted on the thermal shock resistance and the failure mechanism of the coatings. The results show that spraying of Al 2 O 3 ceramic slurries can effectively fill the cracks generated during the process of plasma spraying of NiCrAlY coatings, and metallurgical bonds form between the coatings and the metal substrates. α-Al 2 O 3 and rutile TiO 2 are the main crystalline phase structures of the temperature resistant ceramic coatings. The oxidation rate constant of 2# coating was 1.323 × 10 − 4 mg 2 cm − 4 h − 1 , which shows the best resistance to high temperature oxidation. The effect of high-temperature melting of the Al metal in the bonding layer was found to be beneficial to the bonding strength. Under the same temperature conditions, 2# coating had a higher bonding strength than 1# coating, and when the oxidation time was 96 h, its bonding strength reached up to 26.9 MPa. The thermal expansion coefficient of the NiCrAlY bonding coating fell between those of the metal substrate and ceramic top coating, thus reducing the thermal expansion coefficient difference between the two and decreasing the rate of propagation of the cracks to improve the thermal shock resistance of the coating. An integrated study indicated that 2# coating had a better heat protective performance for the metal substrates.
25 citations
TL;DR: In this article, the effects of preheating temperatures, O2-to-methanol molar (O2/C) ratios, and Pt/Pd ratios on partial oxidation of methanol in sprays and dual-catalyst bed were investigated.
21 citations
TL;DR: In this paper, individual Al2O3 and Cr 2O3 coatings and composite coatings were applied on carbon steel by atmospheric plasma spraying method and the results showed that the Cr2O 3 coating exhibited the best corrosion resistance, due to the densest microstructure and highest adhesion strength.
20 citations
References
More filters
TL;DR: In this paper, the authors used the plasma spray technique to deposit coatings with reconstituted nanostructured Al 2 O 3 /TiO 2 powders and evaluated the abrasive wear resistance of the ceramic coatings using diamond abrasives.
268 citations
TL;DR: In this article, the development of constituent phases and microstructure in plasma sprayed Al2O3-13wt.%TiO2 coatings and reconstituted nanocrystalline feed powder was investigated as a function of processing conditions.
215 citations
15 Apr 2008-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, hot corrosion behavior of three types of plasma sprayed thermal barrier coatings was evaluated: (a) usual YSZ (yttria-stabilized zirconia), (b) particle composite of (YSZ+Al 2 O 3 ) and (c) layer composite of(YSZ/Al 2O 3 ).
Abstract: Hot corrosion is one of the main destructive factors in thermal barrier coatings (TBC s ) which comes as a result of molten salt effect on the coating–gas interface. Hot corrosion behavior of three types of plasma sprayed TBCs was evaluated: (a) usual YSZ (yttria-stabilized zirconia), (b) particle composite of (YSZ + Al 2 O 3 ) and (c) layer composite of (YSZ/Al 2 O 3 ) in which Al 2 O 3 was as a topcoat on YSZ layer. Hot corrosion tests were carried out on the surface of coatings in molten salt (Na 2 SO 4 + V 2 O 5 ) at 1050 °C for 40 h. Spallation was observed in YSZ and (YSZ + Al 2 O 3 ) coatings. The formation of monoclinic ZrO 2 and YVO 4 crystals as hot corrosion products caused the degradation of mentioned TBCs. Although monoclinic ZrO 2 decreased in (YSZ + Al 2 O 3 ) in comparison with usual YSZ, dendritic YVO 4 crystals had main role in degradation of (YSZ + Al 2 O 3 ) coating. Alumina coating as outer layer in YSZ/Al 2 O 3 reduced the penetration of molten salt into YSZ and resulted in the further resistance of TBC against hot corrosion, because the hot corrosion products considerably decreased in YSZ/Al 2 O 3 .
198 citations
TL;DR: In this paper, the hardness, sliding, and erosive wear of the nanostructured alumina coatings (NC) were investigated and compared with that of conventional alumina coating (CC).
111 citations
TL;DR: In this article, the effect of the power to the plasma torch, powder particle size and its distribution and feed rate of the powder on the abovesaid properties of the coatings are explained.
106 citations