| The present study examined influence of oxygen-active elements in the bond coating of thermal barrier coating on a nickel-base superalloy. Utilizing plasma spray techniques, bond coating of Ni-Cr-Al alloys containing various additions of Zr, Y, Hf and Si were coated on a substrate and, then, ceramic layer of ZrO2(Y2O3-stabilized) was coated. After static exposure at 1200℃, Al-depleted zones were formed at the ceramic coating side due to selective oxidation of Al and at the substrate side due to interdiffusion of Al. Cracks appeared to initiate at the Al2O3-bond coating interface, and to propagate into the ceramic coating. Resistance against cracking increased in the order of Y-, Zr- and Hf-addition in the bond layer, while additional Si always improved the cracking resistance. |
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