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.

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.

NiCrAlY Coatings in Yag Laser Combined Low Pressure Plasma Spraying

1998 ◽  
Author(s):  
N. Eguchi ◽  
Z. Zhou ◽  
H. Shirasawa ◽  
A. Ohmori
Keyword(s):  
Laser Irradiation ◽  
Steel Substrate ◽  
High Hardness ◽  
Low Pressure ◽  
Yag Laser ◽  
Pressure Plasma ◽  
Low Pressure Plasma ◽  
Porous Microstructure ◽  
Sprayed Coating ◽  
Plasma Sprayed

Abstract Densification of plasma sprayed NiCrAlY coatings was studied from the view point of hybrid spraying combined with YAG laser irradiation. Configuration of a laser irradiation beam was varied in three different ways while performing low pressure plasma hybrid spraying and the microstructure of each coating was investigated in comparison with a conventional plasma sprayed coating. Of the three types of hybrid spraying, namely, (D pre-laser-irradiation for preheating of a steel substrate, ©simultaneous laser irradiation, and (3) post-laser-irradiation for remelting of the plasma sprayed coating, simultaneous irradiation formed the optimum microstructure showing both the least amount of porosities and high hardness. Some metallurgical bonding was also observed at the interface with this type of spraying. The two other types of hybrid spraying resulted in either a significantly porous microstructure with pre-irradiation, or a low hardness coating with post-irradiation. The characteristics of these microstructures in each coating are explained with reference to thermal hysterisis behaviors.

Evaluation of Adhesive Strengths of Plasma-Sprayed CoNiCrAlY Coatings Using an Indentation Method

2006 ◽  
Vol 306-308 ◽  
pp. 387-392 ◽  
Author(s):  
Hiroyuki Waki ◽  
Izuru Nishikawa ◽  
Akira Ohmori
Keyword(s):  
Thermal Treatment ◽  
Plasma Spraying ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Indentation Method ◽  
Diffusion Treatment ◽  
Barrier Coating ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Low Pressure Plasma Spraying

Thermal barrier coating (TBC) on the element for high temperature service, such as a gas turbine blade, has become an indispensable technology. In this study, adhesive strengths of plasmasprayed CoNiCrAlY coatings were examined using an indentation method. In order to examine the effects of the spraying process on the adhesive strength of a sprayed coating, coatings were deposited by both atmospheric plasma spraying (APS) and low pressure plasma spraying (LPPS). The half number of CoNiCrAlY(LPPS) specimens were thermally aged for diffusion treatment. The load-displacement curves during the indentation were measured, and the delamination energy per unit area of delamination was estimated. The delamination load was high when the distance from an edge of a specimen was long, however the energy per unit delamination area was almost independent of the distance from the edge and was uniquely determined. The delamination energy of CoNiCrAlY(APS) and CoNiCrAlY(LPPS) coatings were found to be approximately the same. The delamination energy of CoNiCrAlY(LPPS) with diffusion thermal treatment was widely scattered as compared with foregoing two coatings, however the energy of the CoNiCrAlY(LPPS) coating with diffusion thermal treatment was found to be about three times higher than those of both CoNiCrAlY(APS) and CoNiCrAlY(LPPS) coatings. It was concluded that diffusion thermal treatment was effective in improving the delamination strength. The CoNiCrAlY(LPPS) coating with diffusion thermal treatment was also found to be effective in improving the fatigue fracture life of a thermal-barrier-coated material.

scholarly journals Optimization of Yb2O3-Gd2O3-Y2O3 Co-Doped ZrO2 Agglomerated and Calcined Powders for Air Plasma Spraying

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 373
Author(s):  
Zheng Yan ◽  
Haoran Peng ◽  
Kang Yuan ◽  
Xin Zhang
Keyword(s):  
Solid Solution ◽  
Particle Size ◽  
Plasma Spraying ◽  
Cubic Phase ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Air Plasma Spraying ◽  
Barrier Coating ◽  
Controllable Preparation ◽  
Co Doped

Yb2O3-Gd2O3-Y2O3 co-doped ZrO2 (YGYZ) is considered to be a promising material in thermal barrier coating (TBC) applications. In this study, 2Yb2O3–2Gd2O3–6Y2O3–90ZrO2 (mol.%) (10YGYZ) feedstock candidates for air plasma spraying (APS) were prepared by calcination of agglomerated powders at 1100, 1200, 1300, 1400, and 1500 °C for 3 h, respectively. Incomplete solid solution was observed in calcined powders at 1100, 1200 and 1300 °C, and the 1500 °C calcined powder exhibited poor flowability due to intense sintering effect. The 1400 °C calcined powders were eventually determined to be the optimized feedstock for proper phase structure (cubic phase), great flowability, suitable apparent density and particle size distribution, etc. 10YGYZ TBCs with the optimized feedstock were prepared by APS, exhibiting pure c phase and good chemical uniformity. Controllable preparation of coatings with different porosity (i.e., 7%–9% and 12%–14%) was realized by stand-off distance adjustment.

scholarly journals High thickness coating of zirconium dioxide for thermal protection of metal alloys

2018 ◽  
Vol 224 ◽  
pp. 03004
Author(s):  
Irina Tsareva ◽  
Olga Berdnik ◽  
Maksim Maximov ◽  
Victor Kuzmin
Keyword(s):  
Thermal Barrier Coating ◽  
Plasma Spraying ◽  
Zirconium Dioxide ◽  
Thermal Protection ◽  
Intermetallic Layer ◽  
High Energy ◽  
Metal Alloys ◽  
Thermal Barrier ◽  
Barrier Coating

A study was made of high thickness thermal barrier coating of zirconium dioxide (up to 2 mm) formed by the method of high-energy plasma spraying on the intermetallic layer, and designed to protect the elements of the fuselage of aircraft.

Influence of Service Temperature on Grain Growth and Thermal Diffusivity of Nanostructured Thermal Barrier Coating

2005 ◽  
Vol 475-479 ◽  
pp. 3985-3988
Author(s):  
Chun Gen Zhou ◽  
Na Wang ◽  
Sheng Kai Gong ◽  
Hui Bin Xu
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Thermal Diffusivity ◽  
Thermal Barrier ◽  
Service Temperature ◽  
Zirconia Coating ◽  
Treatment Results ◽  
Barrier Coating ◽  
Average Grain Size ◽  
Nanostructured Thermal Barrier Coating

The as-sprayed zirconia coating had an average grain size of 67 nm. Thermal treatment results showed that the grains of the nanostructured coating grew slightly below 900°C, whereas over 1000°C the gains grew rapidly. The thermal diffusivity of the coating increases with increasing heat-treatment temperatures.

Effect of environmental pressure on the microstructure of YSZ thermal barrier coating via suspension plasma spraying

2021 ◽  
Vol 41 (1) ◽  
pp. 535-543
Author(s):  
Shiming Xie ◽  
Chen Song ◽  
Zexin Yu ◽  
Shaowu Liu ◽  
Frédéric Lapostolle ◽  
...  
Keyword(s):  
Thermal Barrier Coating ◽  
Plasma Spraying ◽  
Suspension Plasma Spraying ◽  
Thermal Barrier ◽  
Environmental Pressure ◽  
Barrier Coating

Columnar suspension plasma sprayed coating microstructural control for thermal barrier coating application

2016 ◽  
Vol 36 (4) ◽  
pp. 1081-1089 ◽  
Author(s):  
Benjamin Bernard ◽  
Luc Bianchi ◽  
André Malié ◽  
Aurélien Joulia ◽  
Benjamin Rémy
Keyword(s):  
Thermal Barrier Coating ◽  
Thermal Barrier ◽  
Coating Application ◽  
Barrier Coating ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Microstructural Control
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