scholarly journals Effects of surface roughness on CMAS corrosion behavior for thermal barrier coating applications

2021 ◽  
Vol 10 (3) ◽  
pp. 472-481
Author(s):  
Lei Guo ◽  
Guang Li ◽  
Zhilin Gan
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Thermal Barrier Coating ◽  
Capillary Force ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Spreading Area ◽  
Barrier Coating ◽  
Calcium Magnesium ◽  
Yttria Partially Stabilized Zirconia

AbstractCalcium-magnesium-alumina-silicate (CMAS) corrosion is an important cause for thermal barrier coating (TBC) failure, which has attracted increased attentions. In this study, some thermal barrier coating (TBC) materials including YSZ (yttria partially stabilized zirconia), GdPO4, and LaPO4 were prepared into bulks, and the effects of their surface roughness on wettability and spreading characteristics of molten CMAS were investigated. As-fabricated and polished bulks with different surface roughness were exposed to CMAS corrosion at 1250 °C for 1 and 4 h, following by macro and micro observations. Results revealed that compared with the as-fabricated bulks, molten CMAS on the polished samples had lower wettability and a smaller spreading area, mainly attributable to the reduced capillary force to drive the melt spreading. Meanwhile, GdPO4 and LaPO4 bulks exhibited lower CMAS wettability than YSZ bulk. It is thus considered that reducing the surface roughness is beneficial to CMAS corrosion resistance of TBCs.

An Investigation of Phase Crystallinity in Laser Modified Yttria Stabilized Zirconia (YSZ) Thermal Barrier Coating

2014 ◽  
Vol 611-612 ◽  
pp. 1601-1607
Author(s):  
Mohamed Suffian Reza ◽  
Syarifah Nur Aqida ◽  
Mohd Radzi Mohd Toff
Keyword(s):  
Surface Roughness ◽  
Thermal Barrier Coating ◽  
Pulse Repetition Frequency ◽  
Sample Surface ◽  
Yttria Stabilized Zirconia ◽  
Thermal Barrier ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Barrier Coating

This paper presents laser surface modification process of plasma sprayed yttria stabilized zirconia (YSZ) thermal barrier coating (TBC) for enhanced hardness properties and low surface roughness. A 300W JK300HPS Nd: YAG laser was used to process YSZ TBC sample surface. The parameters selected for examination were laser power, pulse repetition frequency (PRF) and residence time. Micrographs of the TBC system were captured using EVO 15 Scanning Electron Microscope (SEM). Surface roughness was measured using 2-dimensional stylus profilometer. X-ray diffraction analysis (XRD) was conducted to measure phase crystallinity of the laser-modified coating surface. X-ray diffraction patterns were recorded in the 2θ range of 10 to 80° using Bruker D8 Advance system with 0.7Å wavelength from a copper source (~1.5Å). The laser modified surface exhibited higher crystallinity compared to the as-sprayed samples. The presence of tetragonal phase was detected in the as-sprayed and laser processed samples. The hardness properties of laser modified TBC increased 15% of the as-sprayed sample. These finding are significant to development of thermal barrier coating design optimization for enhanced surface properties of semi-solid forming die.

Surface Roughness Measurement of Thermal Barrier Coating using Terahertz Waves

2017 ◽  
Vol 137 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Tetsuo Fukuchi ◽  
Norikazu Fuse ◽  
Mitsutoshi Okada ◽  
Tomoharu Fujii ◽  
Maya Mizuno ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Thermal Barrier Coating ◽  
Thermal Barrier ◽  
Roughness Measurement ◽  
Terahertz Waves ◽  
Surface Roughness Measurement ◽  
Barrier Coating

scholarly journals Microstructure and Corrosion Properties of La2Zr2O7/NiCoAlY Thermal Barrier Coatings Deposited on Inconel 718 Superalloy by Laser Cladding

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 101
Author(s):  
Kaijin Huang ◽  
Wei Li ◽  
Kai Pan ◽  
Xin Lin ◽  
Aihua Wang
Keyword(s):  
Corrosion Resistance ◽  
Thermal Barrier Coating ◽  
Laser Cladding ◽  
Inconel 718 ◽  
Electrochemical Techniques ◽  
Thermal Barrier ◽  
Nacl Solution ◽  
Corrosion Performance ◽  
Barrier Coating ◽  
Inconel 718 Superalloy

In order to improve the seawater corrosion resistance of Inconel 718 superalloy, a La2Zr2O7/NiCoCrAlY thermal barrier coating corrosion resistant to 3.5 wt.% NaCl aqueous solution was prepared by laser cladding on Inconel 718 superalloy. X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and electrochemical techniques were used to study the microstructure and the corrosion performance of the coating in 3.5 wt.% NaCl solution. The results show that the thermal barrier coating is mainly composed of primary La2Zr2O7 phase and γ + laves/δ phase eutectic structure. The corrosion potential and corrosion current of the coating in 3.5 wt.% NaCl solution are higher and lower than that of the Inconel 718 substrate, respectively, indicating that the corrosion performance of the coating is better than that of the Inconel 718 substrate. The presence of La2Zr2O7 phase in the thermal barrier coating is the main reason for its corrosion resistance to 3.5 wt.% NaCl solution.

Influence of a Thermal Barrier Coating on the Performance of a Turboprop Engine

1992 ◽  
Author(s):  
J. D. MacLeod ◽  
J. C. G. Laflamme
Keyword(s):  
Surface Roughness ◽  
Thermal Barrier Coating ◽  
Coating Thickness ◽  
Ceramic Coating ◽  
National Research Council ◽  
Engine Performance ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Project Objectives ◽  
The Impact

Under the sponsorship of the Canadian Department of National Defence, the Engine Laboratory of the National Research Council of Canada has evaluated the influence of applying a thermal barrier coating on the performance of a gas turbine engine. The effort is aimed at quantifying the performance effects of a particular ceramic coating on the first stage turbine vanes. The long term objective of the program is to both assess the relative change in engine performance and compare against the claimed benefits of higher possible turbine inlet temperatures, longer time in service and increased time between overhauls. The engine used for this evaluation was the Allison T56 turboprop with the first stage turbine nozzles coated with the Chromalloy RT-33 ceramic coating. The issues addressed in testing this particular type of hot section coating were; 1) effect of coating thickness on nozzle effective flow area; 2) surface roughness influence on turbine efficiency; This paper describes the project objectives, the experimental installation, and the results of the performance evaluations. Discussed are performance variations due to coating thickness and surface roughness on engine performance characteristics. As the performance changes were small, a rigorous measurement uncertainty analysis is included. The coating application process, and the affected overhaul procedures are examined. The results of the pre- and post-coating turbine testing are presented, with a discussion of the impact on engine performance.

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