Water Vapor Corrosion Behavior of Yb2SiO5 Environmental Barrier Coatings Prepared by Plasma Spray-Physical Vapor Deposition

Abstract

Tri-layer Si/mullite/Yb2SiO5 environmental barrier coating (EBC) was prepared on the SiCf/SiC ceramic matrix composite (CMC) by plasma spray-physical vapor deposition (PS-PVD). The EBC samples were carried out with water vapor corrosion at 1300 °C for 200 h. After steam corrosion, Yb2SiO5 layer forms a gradient porous structure. This is mainly due to the inclusion of SiO2-rich layer which is precipitated from the gasification inside the coating and existing a small amount of Yb2O3 separately. During the corrosion process, water vapor infiltrates into the coating and reacts with the SiO2 and Yb2O3 to generate volatile substances. This forms a porous structure to make the coating brittle, resulting in mud cracks finally. In addition, the results show that the Yb2SiO5 can react with the water vapor at the coating surface, forming an Yb2Si2O7 top layer.

Synthesis of Gd2Zr2O7 Coatings Using the Novel Reactive PS-PVD Process

“…Recently, environmental barrier coatings (EBCs) based on ytterbium monosilicate were developed using the PS-PVD process [26]. The properties of this type of coating in different conditions, such as water vapor, were investigated [27]. Gadolinium zirconate is only one type of pyrochlore used in the production of ceramic layers in the PS-PVD process [28].…”

“…Based on Refs. [23][24][25][26][27][28][29], the feedstock materials for new types of ceramic coatings were synthetized before deposition. In this paper, we present our new concept of reactive PS-PVD technology with the synthesis of materials from base oxides during the deposition process.…”

Evaluation of environmental barrier coatings: A review

“…For example, rare-earth monosilicates (RE 2 SiO 5 ) react with SiO 2 to form disilicates RE 2 Si 2 O 7 . 43,44 45 Apparently, this reaction affects the stability and performance of the whole EBCs system. Another example of a chemical compatibility problem happens between EBC and oxidation products observed in the failure of BSAS-based EBCs at a temperature higher than 1300 • C. In the Si/mullite/BSAS EBCs system, BSAS (…”

Xenotime-type high-entropy (Dy1/7Ho1/7Er1/7Tm1/7Yb1/7Lu1/7Y1/7)PO4: A promising thermal/environmental barrier coating material for SiCf/SiC ceramic matrix composites

“…However, when served in a high-velocity combustion environment at high temperatures, the protective SiO2 film on SiC-CMCs will be degraded. This is owing to the simultaneous reaction with water vapor and the low-melting-point oxide mixture of CaO-MgO-Al2O3-SiO2 (CMAS), which can result in the recession of SiC-CMCs in a long-term process [5][6][7][8][9]. Therefore, there is an urgent demand for advanced thermal/environmental barrier coatings (T/EBCs) to increase the high-temperature tolerance and the service life of SiC-CMCs in harsh working conditions [9][10][11][12][13][14][15].…”

“…They display superior high-temperature durability and corrosion resistance in comparison to the first generation (mullite and yttria-stabilized zirconia) and the second generation (1-xBaO•xSrO•Al2O3•2SiO2, 0 ≤ x ≤1) T/EBCs [12,14,[16][17][18]. In addition, rare-earth silicates possess the double advantage of chemical stability together with rather low thermal conductivity [7,[19][20][21][22]. Nevertheless, they are still confronted with the issue of water vapor corrosion owing to the formation of volatile Si(OH)4.…”