Following a summary of other previous group trials undertaken, the results
of this years trial are discussed. For the 1999 group trial a top coating o
f ZrO2 and 8% Y2O3 applied over plasma sprayed bonding layer of NiCrAlY on
Hastelloy-X was chosen for preparation and investigation. The results and m
ethods of preparation and contrasting used are discussed with reference to
photographs of the microstructures obtained.