Microstructures and Characterization of Zirconia Coatings Formed by Laser Combined Plasma Spraying

1998 ◽  
Author(s):  
Z. Zhou ◽  
N. Eguchi ◽  
H. Shirasawa ◽  
A. Ohmori
Keyword(s):  
Laser Irradiation ◽  
Plasma Spraying ◽  
Barrier Properties ◽  
Thermal Barrier ◽  
Irradiation Treatment ◽  
Hybrid Plasma ◽  
Sprayed Coating ◽  
Steel Substrates ◽  
High Temperature Erosion

Abstract Hybrid plasma spraying combined with YAG laser irradiation was studied in order to obtain the optimum zirconia coatings for thermal barrier use. Zirconia coatings of approximately 150 ;Um in thickness were formed on the NiCrAlY under coated steel substrates both by means of conventional plasma spraying and hybrid plasma spraying under a variety of conditions. Post-laser irradiation was also conducted on the plasma as-sprayed coating for comparison. The microstructure of each coating was studied in detail and, for some representative coatings, thermal barrier properties were evaluated by hot erosion and a hot oxidation test. With hybrid spraying, performed under optimum conditions, it was found that a microstructure with appropriate partial densification and without connected porosities was formed and that cracks, which are generally produced in the post-laser irradiation treatment, were completely inhibited. In addition, hybrid spraying formed a smooth coating surface. These microstructural changes resulted in improved coating properties with regard to hardness, high temperature erosion resistance and oxidation resistance.

Microstructure Control of Zirconia Thermal Barrier Coatings by Using YAG Laser Combined Plasma Spraying Technique

1997 ◽  
Author(s):  
Z. Zhou ◽  
N. Eguch ◽  
A. Ohmori
Keyword(s):  
Laser Irradiation ◽  
Plasma Spraying ◽  
Steel Substrate ◽  
Thermal Barrier ◽  
Zirconia Coating ◽  
Yag Laser ◽  
Barrier Coating ◽  
Irradiation Treatment ◽  
Coating Microstructure ◽  
Sprayed Coating

Abstract As an ideal zirconia thermal barrier coating, the coating microstructure with the strong bonding among coating particles and with certain amount porosities in the coating without connected porosity is desirable. However, it is difficult for usual plasma-spraying to create a zirconia coating with these characters. In order to obtain an excellent zirconia coating with these characters, we prepared zirconia coating on steel substrate under coated with NiCrAlY alloys by means of a hybrid spraying (that is, YAG laser combined plasma spraying) and studied the effect of this hybrid spraying process and plasma and laser conditions on the microstructure of coating, and further compared the microstructure of the coating in this hybrid spraying with that in post-laser irradiation of as-sprayed zirconia coating. It is known that the microstructure with densification is formed by the post-laser irradiation of as-sprayed coating and that microcracks are newly produced in the process of rapid cooling. However, by using this newly-developed hybrid spraying, the microstructure with partial densification in the coating without connected porosities was formed and cracks which is generally produced in the post-laser irradiation treatment were inhibited completely. In addition, this hybrid spraying can be done without the post-treatment of coating. Furthermore, the coating properties, such as hardness and wear resistance associated with bonding state among the coating particles in the zirconia coating created by this hybrid spraying were improved.

Characterization of thermal fatigue damage of thermal barrier produced by atmospheric plasma spraying

2004 ◽  
Vol 187 (2-3) ◽  
pp. 185-193 ◽  
Author(s):  
N. Mesrati ◽  
Q. Saif ◽  
D. Treheux ◽  
A. Moughil ◽  
G. Fantozzi ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Fatigue Damage ◽  
Thermal Fatigue ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Thermal Barrier

Synthesis and characterization of black pigments based on calcium manganese oxides for high near-infrared (NIR) reflectance

RSC Advances ◽  
2016 ◽  
Vol 6 (93) ◽  
pp. 90952-90957 ◽  
Author(s):  
Ryohei Oka ◽  
Toshiyuki Masui
Keyword(s):  
Manganese Oxides ◽  
Near Infrared ◽  
Barrier Properties ◽  
Black Pigment ◽  
Synthesis And Characterization ◽  
Thermal Barrier ◽  
Solar Reflectance

Ca2Mn0.85Ti0.15O4 was synthesized as an inorganic black pigment with thermal barrier properties, and its NIR solar reflectance value was much greater than those of the conventional NIR reflective black pigments.

scholarly journals Thermal Stability of YSZ Thick Thermal Barrier Coatings Deposited by Suspension and Atmospheric Plasma Spraying

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 984
Author(s):  
Shiqian Tao ◽  
Jiasheng Yang ◽  
Minglong Zhai ◽  
Fang Shao ◽  
Xinghua Zhong ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Thermal Barrier Coatings ◽  
Thermal Aging ◽  
Thermal Exposure ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Aps Coatings ◽  
Steel Substrates

Two types of segmentation-crack structured yttria-stabilized zirconia (YSZ) thick thermal barrier coatings (>500 μm, TTBCs) were deposited onto the stainless steel substrates using atmospheric plasma spraying (APS) and suspension plasma spraying (SPS) process, respectively. In this work, thermal aging behaviors, such as the microstructures, phase compositions, grain growth, and mechanical properties of APS TTBCs and SPS TTBCs, were systematically investigated. Results showed that both as-sprayed TTBCs exhibited a typical segmentation-crack structure in the through-thickness direction. APS coatings mainly comprised of larger columnar crystals, while a large number of smaller equiaxed grains existed in SPS coatings. Both of the coatings underwent tetragonal-monoclinic phase transformation after 155 °C/40 h heat treatment. The poorer phase stability of SPS TTBCs may have a connection with smaller grain size. Thermal-aged APS and SPS coatings exhibited a significant increase in H and E values with the rising of thermal aging temperature, and for the samples that thermal aged at 1550 °C, the H and E values increased sharply during initial stage then decreased after 80 h due to the phase decomposition. The segmented APS coatings had weak bonding between the lamellaes during thermal exposure, which caused the mean Vickers hardness value of APS TTBCs to be much lower than that of SPS TTBCs.

Microstructural Characterization of Yttria-Doped Zirconia Coatings with Electron Microprobe Wavelength Dispersive Compositional Mapping

2000 ◽  
Vol 645 ◽  
Author(s):  
Ryna B. Marinenko ◽  
Jennifer R. Verkouteren ◽  
David S. Bright
Keyword(s):  
Electron Microprobe ◽  
Microstructural Characterization ◽  
Yttria Stabilized Zirconia ◽  
Annealed Specimen ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Sprayed Coating ◽  
Plasma Sprayed

ABSTRACTThe use of digital electron microprobe x-ray compositional mapping with wavelength dispersive spectrometers to understand the microstructure of yttria stabilized zirconia thermal barrier coatings is described. Data from quantification of element x-ray maps can be utilized to infer what phase or phases are present. Analysis of a plasma-sprayed coating prepared from a fused and crushed feedstock is compared to an annealed specimen of the same material.

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