A coating for jet engines to prevent volcanic ash damage

Following the travel disruption over the last 14 months caused by Icelandic volcanoes Eyjafjallajökull and Grímsvötn, researchers have examined a novel ceramic thermal barrier coating (TBC) that could offer jet engines protection against volcanic ash damage.

Reporting their findings in the June 3, issue of Advanced Materials, Doctoral students Julie Drexler and Andrew Gledhill from Nitin P Padture’s research group at Ohio State University took samples of the ceramic coatings on pieces of metal and coated them with ash from the Eyjafjallajökull eruption. They then heated the samples in a furnace to simulate the high temperatures created in a jet engine. They experimented with a typical jet engine coating and a sand-resistant coating previously developed by Padture, containing zirconia and alumina.

In the test, the ash badly damaged the typical coating, while coatings made of Padture’s formula retained their overall structure. Molten ash had penetrated through the pores of the typical ceramic coating all the way to its base. But in the other two, the molten ash barely penetrated.
"Pores give the coating its strain tolerance,” explained Drexler. "They make room for the coating to expand and contract as the engine heats up and cools. When all the pores are plugged with ash, the coating can’t adjust to the temperature anymore and it breaks off.”