Air plasma-sprayed Y2O3 coatings for Al2O3/Al2O3 ceramic matrix composites

Mechnich, Peter; Braue, W.

doi:10.1016/j.jeurceramsoc.2013.03.034

Cited by 48 publications

(25 citation statements)

References 32 publications

(19 reference statements)

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“…A brief test of nine as-received samples revealed a density of 92% of the theoretical density. Mechnich and Braue [1] reported a similar value of 93% for former batches of the present material. Nevertheless, no established porosity model can explain a loss in stiffness from 170 GPa down to 74 GPa (1200 • C/10 h) or even 47 GPa (as-received) simply based on the magnitude of the porosity of ≈ 9% for this material.…”

Section: Bending Testssupporting

confidence: 81%

“…Furthermore, the material needs to be protected by environmental barrier coatings (EBC) from thermochemical attacks such as corrosion caused by hot gas, ingested dust, sand or volcanic ash. Plasma sprayed yttria coatings are a favorable choice as TBC/EBCs for all-oxide combustor walls for several reasons [1]. The coefficient of thermal expansion matches the alumina-based substrate, and the resistance to corrosion is high in comparison to formerly tested yttria partially stabilized zirconia (Y-PSZ).…”

Section: Introductionmentioning

confidence: 99%

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Crack Growth Tests in Air Plasma-Sprayed Yttria Coatings for Alumina Ceramic Matrix Composites

Hackemann

Bartsch

2019

Ceramics

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Yttria coatings for all-oxide combustor walls were tested for their crack-growth behavior. These environmental and thermal barrier Y2O3-coatings were processed by atmospheric plasma spraying (APS). The stiffness and strength were measured for as-received and aged samples that were heat treated at 1000 °C, 1100 °C and 1200 °C for a 10 h dwell time. The results show a clear development with respect to the aging conditions. The changes of the modulus and the bending strength indicate that the microstructural changes are not completed, even after aging at 1200 °C for 10 h. The fracture toughness was tested for different orientations on samples aged at 1200 °C. Bending tests as well as indentation experiments were conducted. Furthermore, a bending device was designed to observe the crack-growth in situ. The device had to be rigid and is driven by a piezo stack. The crack growth resistance shows differences in the rise of the R-curves for different orientations of the crack propagation. This is in agreement with the microstructure that results from the plasma spray process.

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Section: Bending Testssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Crack Growth Tests in Air Plasma-Sprayed Yttria Coatings for Alumina Ceramic Matrix Composites

Hackemann

Bartsch

2019

Ceramics

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“…This is attributed to the fact that high temperature can accelerate crystallization growth and the formation of the monoclinic β-Y 2 O 3 phase. According to the literature25) , β-Y 2 O 3 grains (i) are much smaller than α-Y 2 O, and (ii) form characteristic lamellae exhibiting a striking similarity to features observed for martensitic transformation.…”

mentioning

confidence: 84%

Thermal behavior and mechanical properties of Y2SiO5 environmental barrier coatings after isothermal heat treatment

Jang

Feng

Lee

et al. 2016

Surface and Coatings Technology

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Y 2 SiO 5 coatings are deposited by a flame-spray technique as protection layer on SiC substrates to prevent oxidation and steam corrosion. In this research, Y 2 SiO 5 coatings were isothermally heat treated at different temperatures and different exposure times in a laboratory environment. The thermal behaviors such as phase transformation, microstructural change and thermally grown oxide (TGO) formation have been examined by XRD, SEM, and EDS analysis. Different modes of TGO growth behavior were found at different temperatures. In addition, the mechanical properties were evaluated by a Martens hardness tester. The results show that the change of microstructure and composition is not too critical, but higher temperatures and longer heating times do lead to the formation of Y 2 SiO 5 crystalline phases and a β-Y 2 O 3 phase. Thus, the isothermal heat treatment improves the hardness and elastic modulus of Y 2 SiO 5 coatings.

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“…The good adhesion can be attributed small TEC mismatch and phase stability, resulting in low driving force for delamination. Another reason for the good adhesion is the formation of yttrium-aluminates at the coating substrate interface leading to chemical bonds between coating and substrate [25]. In Figure 5 the formation of several yttrium-aluminates known from the phase diagram [26] can be observed.…”

Section: Aps Coatings On Ox/ox Cmcsmentioning

confidence: 99%

Environmental Barrier Coatings Made by Different Thermal Spray Technologies

et al. 2019

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Environmental barrier coatings (EBCs) are essential to protect ceramic matrix composites against water vapor recession in typical gas turbine environments. Both oxide and non-oxide-based ceramic matrix composites (CMCs) need such coatings as they show only a limited stability. As the thermal expansion coefficients are quite different between the two CMCs, the suitable EBC materials for both applications are different. In the paper examples of EBCs for both types of CMCs are presented. In case of EBCs for oxide-based CMCs, the limited strength of the CMC leads to damage of the surface if standard grit-blasting techniques are used. Only in the case of oxide-based CMCs different processes as laser ablation have been used to optimize the surface topography. Another result for many EBCs for oxide-based CMC is the possibility to deposit them by standard atmospheric plasma spraying (APS) as crystalline coatings. Hence, in case of these coatings only the APS process will be described. For the EBCs for non-oxide CMCs the state-of-the-art materials are rare earth or yttrium silicates. Here the major challenge is to obtain dense and crystalline coatings. While for the Y2SiO5 a promising microstructure could be obtained by a heat-treatment of an APS coating, this was not the case for Yb2Si2O7. Here also other thermal spray processes as high velocity oxygen fuel (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) are used and the results described mainly with respect to crystallinity and porosity.

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Air plasma-sprayed Y2O3 coatings for Al2O3/Al2O3 ceramic matrix composites

Cited by 48 publications

References 32 publications

Crack Growth Tests in Air Plasma-Sprayed Yttria Coatings for Alumina Ceramic Matrix Composites

Crack Growth Tests in Air Plasma-Sprayed Yttria Coatings for Alumina Ceramic Matrix Composites

Thermal behavior and mechanical properties of Y2SiO5 environmental barrier coatings after isothermal heat treatment

Environmental Barrier Coatings Made by Different Thermal Spray Technologies

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