| JIANG Wu-gui,ZOU Hang,XIA Yu-feng,ZHOU Yu.Effect of Vertical Cracks of Alumina Coating on Interface Failure under Thermal Load[J],48(1):30-36 |
| Effect of Vertical Cracks of Alumina Coating on Interface Failure under Thermal Load |
| Received:June 25, 2018 Revised:January 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.01.004 |
| KeyWord:alumina coating cohesive zone model thermal load finite element interface failure crack density |
| Author | Institution |
| JIANG Wu-gui |
School of Aeronautical Manufacturing Engineering, Nanchang Hangkong University, Nanchang , China |
| ZOU Hang |
School of Aeronautical Manufacturing Engineering, Nanchang Hangkong University, Nanchang , China |
| XIA Yu-feng |
School of Aeronautical Manufacturing Engineering, Nanchang Hangkong University, Nanchang , China |
| ZHOU Yu |
School of Aeronautical Manufacturing Engineering, Nanchang Hangkong University, Nanchang , China |
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| Abstract: |
| To investigate the interface failure mechanism of alumina-coating/aluminum under thermal loads. The residual thermal stress at the interface under thermal loads was predicted, and the interface failure of the alumina-coating/aluminum was systematically studied by the finite element model with a cohesive zone. The effects of the coating thickness, the thermal load magnitude, and the vertical crack density of the coating on the stress field at the interface and the interface damage failure were considered and compared with experiments. Experimental and simulation results showed that, as the interface was cooled after heated to 300 ℃, no parallel cracks was observed at the interface. However, as the interface was heated to 400 ℃ and then cooled, parallel cracks were observed at the interface. The shear stresses at the interface showed a single-curve cosine distribution when there was no crack defect in the coating, while the shear stresses showed a hyperbolic cosine distribution when there was vertical cracks in the coating. With the increase of thermal load, the maximum shear stress at the interface migrated from both ends to the center. Coatings without vertical cracks had a minimum average normal stress compared to coatings with vertical cracks. However, the actually prepared alumina coating was unlikely to be free of defects. When the coating crack density was 4 mm?1, the average residual normal stress was small, and the interface had only tensile stress, which caused the interface to be less likely to delaminate. There is a specific optimum critical pre-fabricated vertical crack density value, which minimizes interface failure under thermal loading. The finite element results also indicate that, the thicker the coating is, the stronger the thermal protection of interface is under the same thermal load and the same density. |
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