OXIDATION AND PROTECTION OF SUPERALLOY IC-6

NiCoCrAlY coating was deposited on a new Ni 3Al-base alloy IC-6 using arc ion plating.The oxidation kinetic curves of alloy IC-6,Ni-base alloy K17 and NiCoCrAlY coated alloy IC-6 at 900℃～1100℃ were obtained.The results indicate that exposed at 900℃,the oxide scales of alloy IC-6 consist of α-Al 2O 3?NiAl 2O 4 and NiO.A small amount of NiMoO 4 and MoO 2 were also detected.At 1050℃ and 1100℃,lose weight occurred due to the formation of volatile MoO 3.The oxidation weight gain rate of the NiCoCrAlY coating deposited on alloy IC-6 obeyed the parabolic rate law at different temperatures.The coating combined with alloy IC-6 closely and no spalling and void between the coating and the interface of the substrate were observed.The coating oxidation resistance remarkably improved with α-Al 2O 3 scales that formed and covered on the coating at 900℃ and both α-Al 2O 3 and Cr 2O 3 scales on the coating at 1050℃.The effectiveness of NiCoCrAlY coating was not distinctive at 1100℃ due to NiAl 2O 4 and NiO growing on the surface of coating.The formation of α-Al 2O 3 and Cr 2O 3 scale is the directly reason of remarkable improvement of oxidation resistance of superalloy IC-6 covered with NiCoCrAlY coating.