Inhibition Behavior of LZO on the Oxidation of Bond-coat in Thermal Barrier Coatings

In order to clarify the inhibitory effect of LZO (La2Zr2O7) on the oxidation of bond-coat in thermal barrier coatings (TBCs), NiCoCrAlY bond-coat was deposited on 310S substrate by detonation gun spraying, and single ceramic 8YSZ coating and LZO/8YSZ double ceramic coating were deposited by air plasma spraying. The microstructure and phase structure of TBCs before and after high temperature oxidation were analyzed by SEM, EDS and XRD. The results show that the relative oxidation mass gain of the double ceramic LZO/8YSZ and the single ceramic 8YSZ structure are 2.82 and 3.13 mg/cm(2), respectively. Their TGO (thermally grown oxide) growth rate constant K-p is 5.79 x 10(-2) and 6.26 x 10(-2) m(2)/h, respectively. And the corresponding thickness distribution range is 3.75 similar to 5.25 mu m and 5 similar to 5.5 mu m, respectively after isothermal oxidation (100 h) at 1100 degrees C. Compared with the single ceramic 8YSZ TBCs, TGO exhibits obvious characteristics which are less oxidation mass gain, lower growth rate, and slower beta phase transition in bond-coat of the LZO/8YSZ double ceramic TBCs.