等离子喷涂热障涂层微裂纹模拟研究
Simulation on Micro-crack in Plasma Sprayed Thermal Barrier Coating
华 丹, 范群波, 沈 伟, 杨学文
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作者单位：(北京理工大学 材料学院, 北京 100081)
中文关键字：热障涂层； 粗糙度； 横向裂纹； 纵向裂纹
英文关键字：thermal barrier coatings; roughness; horizontal crack; vertical crack
中文摘要：采用有限元法模拟了片层粒子中微裂纹的萌生和扩展过程。模拟结果表明，在特定的基体粗糙表面上，横向裂纹在垂直方向(Y方向)应力作用下沿片层粒子与基体界面附近开裂，横向裂纹平均长度lh =0.37ds (ds为片层粒子直径)；而纵向裂纹则由于在片层粒子的腰部区域存在几何突变，在该处呈现出更高的水平方向(X方向)应力，导致裂纹大部分以近乎与基体垂直角度贯穿片层粒子腰部区域，并普遍优先于横向裂纹开裂，纵向裂纹平均长度 lv =0.37hs (hs为片层粒子厚度)。研究发现，横向裂纹长度随撞击速度的增大而变长，而纵向裂纹长度随撞击速度的增大而变短。
英文摘要：The initiation and propagation process of micro-crack in lamellar grain was numerically studied. It is found that, for the specific surface roughness, the horizontal crack initiates along the interface of the splat and substrate due to the stress in vertical direction(Y direction), the mean length of horizontal crack is lh =0.37 ds (ds is the diameter of lamellar grain). However, the vertical crack initiates in the geometric mutation region where a higher stress in horizontal direction(X direction) exists. The vertical crack initiates earlier than horizontal crack, and the mean length of vertical crack is lv =0.37 hs. The results indicate that the length of horizontal crack increases with the increase of the initial velocity. On the contrary, the length of vertical crack decreases with the increase of the initial velocity.