Corrosion of Ceramic Materials

Herrmann, Matthias; Klemm, Hagen

doi:10.1016/b978-0-08-096527-7.00034-9

Cited by 11 publications

(6 citation statements)

References 141 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Environmental barrier coatings (EBCs) are needed to protect the material from degradation [4]. (1) An EBC should have a high resistance against water vapor at elevated temperatures; therefore, the corrosion rates of many materials were studied in the past (see Fritsch et al [5][6][7][8], Herrmann et al [9]). Besides the corrosion resistance, the coefficient of thermal expansion (CTE) is a crucial parameter for the performance of an EBC.…”

Section: Introductionmentioning

confidence: 99%

YAlO3—A Novel Environmental Barrier Coating for Al2O3/Al2O3–Ceramic Matrix Composites

et al. 2019

View full text Add to dashboard Cite

Ceramic matrix composites (CMCs) are promising materials for high-temperature applications. Environmental barrier coatings (EBCs) are needed to protect the components against water vapor attack. A new potential EBC material, YAlO3, was studied in this paper. Different plasma-spraying techniques were used for the production of coatings on an alumina-based CMC, such as atmospheric plasma spraying (APS) and very low pressure plasma spraying (VLPPS). No bond coats or surface treatments were applied. The performance was tested by pull–adhesion tests, burner rig tests, and calcium-magnesium-aluminum-silicate (CMAS) corrosion tests. The samples were subsequently analyzed by means of X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Special attention was paid to the interaction at the interface between coating and substrate. The results show that fully crystalline and good adherent YAlO3 coatings can be produced without further substrate preparation such as surface pretreatment or bond coat application. The formation of a thin reaction layer between coating and substrate seems to promote adhesion.

show abstract

Section: Introductionmentioning

confidence: 99%

YAlO3—A Novel Environmental Barrier Coating for Al2O3/Al2O3–Ceramic Matrix Composites

et al. 2019

View full text Add to dashboard Cite

show abstract

“…However, in a gas turbine, the oxidative atmosphere also contains fast flowing water vapor. This water vapor leads to the formation of volatile (oxy) hydroxides, which remove the scale and can lead to massive damage to the whole component [4,5]:…”

Section: Introductionmentioning

confidence: 99%

Correlation of Process Conditions, Porosity Levels and Crystallinity in Atmospherically Plasma Sprayed Yb2Si2O7 Environmental Barrier Coatings

et al. 2021

View full text Add to dashboard Cite

Environmental barrier coatings are necessary to protect fibre reinforced ceramics from high recession rates in fast and hot water vapor-containing gases as they typically are found in the hot gas sections of gas turbines. A standard material to protect SiC/SiC composites is atmospherically plasma sprayed (APS) Yb2Si2O7. For this material, it is difficult to obtain at reasonable substrate temperatures both low porosity and high crystallinity levels during APS. In this paper results of coatings prepared by a so-called high velocity APS process and also more conventional processes are presented. All coatings have been prepared by a single layer deposition method which avoids inter passage porosity bands. Furthermore, the samples were heat-treated in air at 1300 °C for 100 h and the influence of the topcoat density on the growth of the silica scale on the used silicon bond coat was studied.

show abstract

“…Obviously, the ideal EBC should have high corrosion resistance and should be stable at high temperatures. To identify potential EBC candidates, corrosion rates of several materials have been studied . Water vapor corrosion rates of an Al 2 O 3 /Al 2 O 3 ‐CMC and possible coating materials are shown in Table .…”

Section: Introductionmentioning

confidence: 99%

Improved Adhesion of Different Environmental Barrier Coatings on Al₂O₃/Al₂O₃‐Ceramic Matrix Composites

et al. 2020

View full text Add to dashboard Cite

Among other things, the efficiency of a gas turbine is limited by its maximum service temperature, which is determined by the thermomechanical capabilities of the components in the hightemperature section of the turbine. Decades of research are therefore aiming for solutions that enable a further increase in the turbine inlet temperature. In the past years, the maximum service temperature could be drastically increased by the use of thermal barrier coatings (TBCs) and complex cooling systems. Unfortunately, the extra work that is needed for cooling causes high-efficiency losses. Calculations showed that operation at 1300 C without cooling could increase the output power by almost 50%. [1,2] Another factor, especially relevant to applications in aviation, is the reduction of weight. Any weight reduction reduces fuel consumption not only by the amount of the original mass which does not need to be accelerated, but also by the mass of the saved fuel. Therefore, the desire to further optimize the process generates the demand for lighter materials with a higher thermomechanical stability compared with the singlecrystal superalloys that are frequently used up to now. Ceramic matrix composites (CMCs) based on oxides, for example, alumina, are suitable materials to meet the increasing requirements for high-temperature applications in gas turbine environment. This is due to their excellent temperature stability, [3,4] as well as due to their reduced weight compared with current state-of-theart nickel-based alloys. Although alumina is quite inert, water vapor that is present in the aggressive turbine atmosphere (%10%) [5,6] can cause severe corrosion, as it leads to the formation of volatile hydroxides at temperatures above 1200 C. [7] Therefore, the application of suitable environmental barrier coatings (EBC) to mitigate this corrosion is inevitable for long-term use. Al 2 O 3ðsÞ þ 3H 2 O ðgÞ 2AlðOHÞ 3 ðgÞ (1) Obviously, the ideal EBC should have high corrosion resistance and should be stable at high temperatures. To identify potential EBC candidates, corrosion rates of several materials have been studied. [8-14] Water vapor corrosion rates of an Al 2 O 3 / Al 2 O 3-CMC and possible coating materials are shown in Table 1. In addition to a high water vapor resistance, a dense microstructure is preferred to suppress the diffusion of water through the coating. However, a dense coating can cause high stresses during thermal cycling, leading to premature failure. To achieve a long service life, a low coefficient of thermal expansion (CTE) mismatch between coating and substrate is advantageous. Considering that, materials such as Y 2 O 3 and yttrium aluminates appear to be more suitable than yttria-stabilized zirconia (YSZ) and Gd 2 Zr 2 O 7. The suitability of Y 2 O 3 as EBC for oxide-based WHIPOX CMCs has been studied by Mechnich et al. and was also demonstrated on real combustor components. [23,24] Prior to coating by atmospheric plasma spraying (APS), a reaction-bonded aluminium oxide (RBAO) bond coat was applied to increas...

show abstract

Corrosion of Ceramic Materials

Cited by 11 publications

References 141 publications

YAlO3—A Novel Environmental Barrier Coating for Al2O3/Al2O3–Ceramic Matrix Composites

YAlO3—A Novel Environmental Barrier Coating for Al2O3/Al2O3–Ceramic Matrix Composites

Correlation of Process Conditions, Porosity Levels and Crystallinity in Atmospherically Plasma Sprayed Yb2Si2O7 Environmental Barrier Coatings

Improved Adhesion of Different Environmental Barrier Coatings on Al₂O₃/Al₂O₃‐Ceramic Matrix Composites

Contact Info

Product

Resources

About

Corrosion of Ceramic Materials

Cited by 11 publications

References 141 publications

YAlO3—A Novel Environmental Barrier Coating for Al2O3/Al2O3–Ceramic Matrix Composites

YAlO3—A Novel Environmental Barrier Coating for Al2O3/Al2O3–Ceramic Matrix Composites

Correlation of Process Conditions, Porosity Levels and Crystallinity in Atmospherically Plasma Sprayed Yb2Si2O7 Environmental Barrier Coatings

Improved Adhesion of Different Environmental Barrier Coatings on Al2O3/Al2O3‐Ceramic Matrix Composites

Contact Info

Product

Resources

About

Improved Adhesion of Different Environmental Barrier Coatings on Al₂O₃/Al₂O₃‐Ceramic Matrix Composites