Abradable Coatings & Seal Linings
Abradable coatings are sacrificial layers. When a rotating blade or seal knife touches the coating, the coating wears away and the part doesn’t. That lets a machine run with a tight clearance and adjust itself as heat and load change. A&A Coatings applies plasma-sprayed abradable seal coatings and seal linings to compressors, turbines and expanders, for OEM builds and MRO repair.
What Abradable Coatings Do
Every rotating machine needs a small gap between the spinning parts and the housing. If the gap is too wide, gas leaks past the blades and efficiency drops. If it is too tight, the blade tips rub the case and get damaged.
An abradable coating fixes that. We spray a layer onto the stationary surface, such as a compressor case or a shroud. The layer is soft enough for a blade tip to cut its own groove. As the machine heats up, spins up or flexes under load, the blades wear in their own path. The coating gives way and the blade doesn’t.
The coating has to do two jobs at once. It must be soft enough to cut, and tough enough to stand up to the gas stream. That balance is what makes a good seal lining.
Abradable Material Systems We Apply
We plasma spray aluminum-polyester and aluminum-graphite abradables for precision clearance control. The powders strike a balance between abradability and erosion resistance, and their quality keeps the lining durable in service. Typical machines are cryogenic radial expansion turbines, centrifugal compressors and gas turbines, aircraft jet engines among them.
Each material has its own data sheet with composition and use notes. If you are not sure which one fits your clearance and operating temperature, send us the details and we will recommend one.
Advantages of Abradable Coatings
We tailor each coating to the industry and the part. These are the main advantages of abradable linings from A&A Coatings:
- Stands up well to oxidation
- Copes with thermal shock
- Handles impact
- Strong internal cohesion
- Cuts cleanly when a blade touches it
- Low friction
- Abradability balanced against erosion resistance
- No wear on the blade or its tip from contact with the coating
Where They’re Used
Abradable linings go anywhere a rotor spins inside a housing and efficiency depends on the gap. Typical uses include:
- Compressor cases and shrouds
- Expander shrouds in cryogenic turbines
- Labyrinth seals
- Gas turbine and jet engine sections
- Centrifugal compressor stages
For OEM work, we coat new cases and seal rings to your drawing. For MRO work, we restore worn linings so the machine goes back into service at its design clearance.
Parts We Coat With Abradables
Abradables go onto many kinds of industrial machinery. These parts reach our shop most often.
Most of the work is on shafts, drive collars and labyrinth seals, along with turbine wheels, compressor wheels, compressor impellers and compressor shrouds. On the expander side, we coat wheels, impellers and shrouds.
The Process: Plasma Spray
We apply abradables with plasma spray. A plasma gun turns an inert gas into a very hot plume. We feed powder into the plume, and the particles hit the prepared surface and build the coating one pass at a time. The heat stays in the plume. The part itself stays below 250°F, so cases and shrouds keep their shape.
Surface prep comes first. We clean the part and grit blast it to a fresh, rough profile so the coating can grip. After spraying, abradables are machined to size, never ground. Our own machining and grinding department does that work, so your part doesn’t leave the building between coating and final clearance.
Specs & Tolerances
Thickness, hardness and surface finish depend on the material system, the mating blade material and the operating temperature. We set them for each job, and your drawing or specification controls the final numbers.
If you already have a spec, send it with your quote request. If you are still working out the clearance, our engineers can talk it through with you.
OEM / MRO Service Notes
We take one-off repairs and production runs. Part size matters for these jobs, so here is what the shop can handle: turning up to 48 inches in diameter, grinding up to 30 inches, and blast booths up to 15 by 15 by 30 feet.
Our facility is certified under MIL-STD-1687A, the Navy thermal spray coating standard. Quotes go out within 24 hours, and we answer every inquiry the same business day.
Request a Quote
To price an abradable coating job, send us a drawing or photo, the base material, the operating temperature, the mating blade material, the quantity and the date you need the part back. Upload files up to 8 MB on our quote form or call 888-679-5460.
A&A Coatings has been spraying thermal coatings since 1944. If you are weighing an abradable lining for a compressor, turbine or expander, talk to us about your machine.
Want to learn more about A&A Coatings? Call us today at 888-679-5460 or CONTACT US
FAQs
What is an abradable coating?
The coating gives up material so the blade tips don’t. It is a sprayed layer on a stationary surface that wears away when a rotating part touches it. The result is a tight, self-adjusting seal clearance.
How does an abradable seal coating improve efficiency?
It closes the gap between rotor and housing. Less gas leaks past the blades, so the machine does more useful work. The coating also lets the machine run tight without risking damage when parts expand with heat.
What materials do you use for abradable coatings?
We spray aluminum-polyester and aluminum-graphite composite with plasma spray. Each has its own data sheet. Tell us the operating temperature and blade material, and we will suggest the best fit.
Can you restore a worn seal lining?
Yes. MRO work is a large part of what we do on abradables. We restore the worn lining and machine it back to the clearance your drawing calls for, all in one shop.
What do you need to quote an abradable coating job?
A drawing or photo, the base material, the operating temperature, the mating blade material, the quantity and your date. Upload files up to 8 MB through our quote form. We send quotes within 24 hours.
