Application of thermal barrier coatings on combustion chamber liners - A review

Abstract

Thermal barrier coatings (TBC) help to reduce the temperature of combustion chamber liner by 473-573K during operation on being aided by swirls of film cooling air. Versatility and low production cost make air plasma spray (APS) TBCs more attractive on liners. However spinal formation at the top to bond coat interface induces ceramic sintering rate and forms thermally grown oxide (TGO) growth. Lifing of engines is attempted to utilize existing design and remnant life within design constrains by giving emphasis on coating philosophies. A proper and efficient substitute with multimetallic bond coat and ceramic topcoat yields longer hours of exposure. Parallel removal of harmful elements in the liner material, restriction on the use of poor quality fuels, and atmospheric effects increase life. Studies of remnant life assessment have been found to be based on control of parameters that check TGO growth, increase adhesion of thicker TGO and restrict ceramic top coat sintering. For example, ceria or lanthana stabilized zirconia transform at comparatively higher temperature than yttria stabilized zirconia. The current scenarios of protection have been changed to replacements by continuous fiber ceramic composite (CFCC), and ceramic matrix composites (CMC) component; e.g. Sylramic, Nicalon, Naxtal, and Ceracurb. Non-destructive examination of ceramic translucence based on Parker's optical property produces in-situ information about ceramic degradations.