Diagnostics Correlation Study of 8%-YSZ Deposited by F4-MB APS Torch

Modern gas turbine hot sections need to be protected from elevated temperature and damaging environments. This protection starts as a typically two layer coating system, the base layer or bond coat (BC) acts as a corrosion barrier and a kind of buffer for the thermal mismatch between the base material and the second top thermally protective layer or Thermal Barrier Coating (TBC). The BC is normally a metallic MCrAlY type coating where M is Ni and/or Co. The TBC is a high temperature stable ceramic material; alumina and 5-8at% Yttria Stabilized Zirconia (YSZ) coatings are use on most components. Both types of coating BC and TBC’s are commonly deposited by thermal spray operations from a fine starting powder. Bond coats are commonly deposited by a process called high velocity oxy-fuel (HVOF), and TBC’s are deposited by plasma thermal spray.