Pages 223-224
It is well known, that thermally grown oxide (TGO) is formed at an interface of thermal barrier top coating (TBC) and bond coating during service. In the previous work, TGO layer contained at least two layers with different oxides was observed by SEM images. One was Al_2O_3,and the other was mixed oxide of NiO, CoO, Cr_2O_3,or their spinels. It was supposed that a reason of the macro-crack formation near an interface is due to decrease in bond strength or due to formation of stress concentration site caused by a formation of pores in the mixed oxide. In order for an improvement of bond strength, a modified bond coating material was developed which was MCrAlY with Ce and Si addition. Four point bending tests were carried out to measure a bond strength on conventional TBC and modified TBC with modified bond coating. As a result, the TBC with modified bond coating had superior bond strength than conventional one. It is likely that the reason can be a decrease of mixed oxide formation.
