Spalling resistance of thermally grown oxide based on NiCoCrAlY（Ti） with different oxide peg sizes
来源期刊：Rare Metals2021年第3期
论文作者：Liang Yang Ryutan Choi Yu Zheng Mohammad Hassan Shirani Bidabadi Abdul Rehman Chi Zhang Hao Chen Zhi-Gang Yang
摘 要：NiCoCrAlY is usually used as the material to bond-coat in thermal barrier coating systems under high temperatures.Using NiCoCrAlY and adding different amounts of the active element Ti（0,0.1,0.3,and0.5;wt%）,the relationship between oxide peg size and thermally grown oxide spalling resistance is ascertained by examining specimens subjected to a cyclic oxidation experiment.Oxide pegs,consisting of a Y-and Ti-rich oxide core and an outer Al2 O3 sheath,are formed by Ti and A1 successively reacting with oxygen after the rapid generation of Y-rich oxide.The size of the oxide pegs with higher Ti concentrations is on average bigger in the alloy.Severe thermally grown oxide spalling occurred in the0.5 wt% Ti specimen,but in the 0.3 wt% Ti specimen,it displayed the best adherence with the alloy due to the presence of fine pegs.Cavities existed at the interface between the inner oxide core and outer Al2 O3 sheath of larger pegs serve as microcrack sources and further induce severe scale failure combined with the initial interface crack between the scale and alloy.
Liang Yang1，Ryutan Choi2，Yu Zheng1，Mohammad Hassan Shirani Bidabadi1，Abdul Rehman1，Chi Zhang1，Hao Chen1，Zhi-Gang Yang1
1. Key Laboratory for Advanced Materials of Ministry of Education,Department of Materials Science and Engineering,Tsinghua University2. Department of Defect Control,Samsung Electronics
摘 要：NiCoCrAlY is usually used as the material to bond-coat in thermal barrier coating systems under high temperatures.Using NiCoCrAlY and adding different amounts of the active element Ti（0,0.1,0.3,and0.5;wt%）,the relationship between oxide peg size and thermally grown oxide spalling resistance is ascertained by examining specimens subjected to a cyclic oxidation experiment.Oxide pegs,consisting of a Y-and Ti-rich oxide core and an outer Al2 O3 sheath,are formed by Ti and A1 successively reacting with oxygen after the rapid generation of Y-rich oxide.The size of the oxide pegs with higher Ti concentrations is on average bigger in the alloy.Severe thermally grown oxide spalling occurred in the0.5 wt% Ti specimen,but in the 0.3 wt% Ti specimen,it displayed the best adherence with the alloy due to the presence of fine pegs.Cavities existed at the interface between the inner oxide core and outer Al2 O3 sheath of larger pegs serve as microcrack sources and further induce severe scale failure combined with the initial interface crack between the scale and alloy.
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