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Slurry-based Protective Coatings for Oxide/Oxide Composites

Mechnich, Peter (2019) Slurry-based Protective Coatings for Oxide/Oxide Composites. 13th International Pacific Rim Conference on Advanced Ceramic & Glass Technoloy (PacRim-13), 27.-31. Okt. 2019, Ginowan, Japan.

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Abstract

Ceramic matrix composites based on oxide fibers and porous oxide matrices are attractive materials for various applications in harsh environments. State-of-the art all-oxide CMC are based on alumina or mullite fibers and porous matrices. A key issue is the relative low mechanical stability of the porous oxide matrices, therefore CMC surfaces are prone to selective erosion in high-velocity gas stream. Moreover, thermo-chemical degradation of the constituents SiO2 and Al2O3 is associated with hydroxylation in hot H2O-rich atmospheres and subsequent volatilization of Si- or Al-hydroxide species. Degradation of CMC can effectively be reduced by protective coatings. Beyond classical coating techniques such as thermal spraying, a simple process based on deposition of slurry based coatings and subsequent consolidation by sintering is attractive for cost-efficient fabrication of CMC components. A serious drawback, however, is the low thermal stability of state-of-the art oxide fibers which requires short-term sintering of slurry-based coatings at temperatures not exceeding about 1300°C. This can be achieved by means of transient phases which bond particles and substrate at moderate temperatures. Since transient phases are reactive constituents, no residual non-crystalline phases affecting thermal stability are present after processing. Due to the rigid CMC substrates sintering of coatings is constrained, therefore excess volume shrinkage during processing must be avoided. As a consequence, slurry based coatings for all-oxide CMC exhibit generally a relative high porosity. Examples presented include slurry based coatings consisting of Al2O3, SiO2, Y2O3, and ZrO2.

Item URL in elib:https://elib.dlr.de/130305/
Document Type:Conference or Workshop Item (Speech)
Title:Slurry-based Protective Coatings for Oxide/Oxide Composites
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Mechnich, PeterPeter.Mechnich (at) dlr.deUNSPECIFIED
Date:October 2019
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:CMC, Coating
Event Title:13th International Pacific Rim Conference on Advanced Ceramic & Glass Technoloy (PacRim-13)
Event Location:Ginowan, Japan
Event Type:international Conference
Event Dates:27.-31. Okt. 2019
Organizer:The Japanese Ceramic Society
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:propulsion systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Combustion Chamber Technologies
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Structural and Functional ceramics
Deposited By: Mechnich, Dr.rer.nat. Peter
Deposited On:21 Nov 2019 09:02
Last Modified:21 Nov 2019 09:02

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