Journal of Vacuum Science & Technology A, Vol.26, No.6, 1439-1442, 2008
Surface sealing of electron beam physical vapor deposited thermal barrier coatings by high-intensity pulsed ion beam
A surface sealing technology by employing high-intensity pulsed ion beam (HIPIB) technique is developed for electron beam physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) to further improve the high temperature performance. The HIPIB irradiation can deliver a high-density energy up to 100 J/cm(2) into the shallow ion range of about 0.1-10 mu m within a short pulse width of less than 1 mu s, by which a micrometer-thick bridging layer was achieved on the gap between columnar grains of EB-PVD TBCs under a single pulse of 4.5 J/cm(2). The thin bridging layer provided atmosphere shielding for the TBCs along with matching strain tolerance of the columnar top coat during thermal cycling. Cyclic oxidation tests at 1050 degrees C demonstrated that weight gain of the sealed TBC samples is decreased by about 60% from 0.8 mg/cm(2) of the as-deposited ones.
Keywords:ceramics;electron beam deposition;ion beam assisted deposition;surface treatment;thermal barrier coatings;yttrium compounds