Effect of Bonding Layer Roughness on Thermal Shock Performance of YSZ Coating

LI Guo-hao, BA De-chun, NI Yan-song, TAN Zhen, CHEN Hong-bin, DU Guang-yu

Surface Technology ›› 2021, Vol. 50 ›› Issue (7) : 310-317, 336.

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Surface Technology ›› 2021, Vol. 50 ›› Issue (7) : 310-317, 336. DOI: 10.16490/j.cnki.issn.1001-3660.2021.07.032
Corrosion and Protection

Effect of Bonding Layer Roughness on Thermal Shock Performance of YSZ Coating

  • LI Guo-hao1, BA De-chun1, NI Yan-song1, CHEN Hong-bin1, DU Guang-yu1, TAN Zhen2
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Abstract

The effect of the surface treatment of the bonding layer on the thermal cycle life of the YSZ coating was studied. Flame spraying and plasma spraying were used to prepare NiCoCrAlY bonding layer and 8YSZ ceramic layer on GH4169 superalloy. Before preparing the ceramic layer, the surface of the bonding layer is treated by low-pressure sandblasting to change the surface roughness of the bonding layer. X-ray diffractometer (XRD), scanning electron microscope (SEM), 3D measuring laser microscope were used to characterize the phase, microscopic morphology and surface roughness of the coating. Muffle furnace was used to perform a thermal cycle experiment at 1100 ℃ to characterize the thermal shock performance of the YSZ coating. The surface of the adhesive layer prepared by spraying method is rough, and the surface condition is effectively improved after sandblasting. The surface roughness decreases by 1~3 μm. The thermal growth oxide (TGO) formed between the ceramic layer and the bonding layer increases during the thermal shock test. The oxidation rate of the sandblasted coating is reduced. After the thermal shock test, microcracks appeared at the edge of the coating, and with the accumulation and expansion of the cracks, the coating peeled. There was no phase transition in YSZ before and after coating failure. The coating failure occurred at the TGO interface. The high temperature oxidation of the adhesive layer caused the growth and thickening of the TGO layer, which lead to the failure of the coating. The relatively smooth interface can reduce the contact area and reduce the oxidation rate of the adhesive layer. Smooth interface can avoid excessive growth of TGO. The coating with sandblasted surface has higher thermal shock resistance.

Key words

TBC; bonding layer; surface treatment; thermal shock resistance; 8YSZ; failure study

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LI Guo-hao, BA De-chun, NI Yan-song, TAN Zhen, CHEN Hong-bin, DU Guang-yu. Effect of Bonding Layer Roughness on Thermal Shock Performance of YSZ Coating[J]. Surface Technology. 2021, 50(7): 310-317, 336
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