Thermal barrier coating manufacture is based on two different processi
ng technologies, namely thermal spraying and electron beam physical va
pour deposition (EB-PVD) of a yttria stabilised, zirconia ceramic. The
former is widely used to deposit ceramics on combustor cans, ductwork
, platforms and other hot gas path components. The latter, due to its
unique columnar structure, is the only process that can offer satisfac
tory levels of spall resistance, erosion resistance and surface finish
retention for aerofoil applications. By using a unique high velocity
gas gun rig, that has been developed with the capability of impacting
thermal barrier coatings at particle velocities upto 300m/s at test te
mperatures up to 920 degrees C, this paper contrasts the erosion behav
iour of an APS and EB- PVD ZrO2-8wt%Y2O3 ceramic. When subjected to ro
om temperature erosion using 100 mu m Al2O3, the erosion rate of an EB
-PVD thermal barrier ceramic was observed to be an order of magnitude
lower than its plasma sprayed counterpart. At high temperatures erosio
n rates increased over those measured at room temperature, consistent
with the higher test velocities achieved at 910 degrees C. Post test e
xamination showed that cracking occurs within the near-surface region
of the EB-PVD ceramic, and that erosion results from material loss as
cracks propagate parallel to the coating substrate interface, the crac
ks being arrested by the major columnar boundaries. In contrast, remov
al of material for plasma sprayed coatings occurs through poorly bonde
d splat boundaries, and hence larger volumes of material are easily lo
st resulting in higher erosion rates.