Coating on compressor and turbine shrouds, seals and casings designed to be worn away cleanly by blade tips or knife edges without damaging them, leaving the smallest possible gap. Materials include aluminum-silicon with polyester, nickel-graphite, nickel-chrome-aluminum with bentonite and porous ceramics, often sprayed with a pore-forming filler. The engineering balance is cutting easily while still resisting gas erosion.
Abradable on the stage 3 shroud is too hard, the blade tips are getting smeared and blued.
Also heard as
- abradable seal
- abradable coating
- clearance control coating
Related terms
Porosity
The fraction of a coating's volume made of voids between and within splats, usually reported in percent.
Plasma spray
Spraying powder through an electric arc plasma jet hot enough to melt ceramics and refractory metals.
Microhardness
Hardness of a coating measured with tiny diamond indents on a polished cross section.
Strip and respray
Removing a failed or worn coating completely and applying a new one, a standard repair and rework.