隔热可磨耗封严涂层界面断裂行为的数值模拟

Numerical Simulation of Interfacial Fracture Behavior of Heat-Insulating and Abradable Seal Coatings

为探究隔热可磨耗封严涂层的失效行为,研究了界面粗糙度、界面附近可磨耗面层结构对复合涂层开裂的影响规律。采用内聚力模型以及相场法描述裂纹沿界面整体剥落以及可磨耗面层内部断裂行为,揭示了涂层的剥落失效机理。研究发现,随着界面粗糙度的增加,涂层结合强度和开裂趋势呈现相反的变化规律。一方面,无损伤复合涂层界面有效接触面积增大,结合强度提高;另一方面,随着粗糙度的增加,面层内部断裂更加容易。因此,需合理优化界面粗糙度。此外,界面附近面层孔隙会降低界面处的结合强度。据此,选择合适的界面粗糙度,并在可磨耗面层与隔热层之间引入抗开裂致密过渡层,以消除面层孔隙对复合涂层界面强度的弱化作用,设计出抗开裂涂层。

In order to explore the failure behavior of heat-insulating and abradable seal coating, the effects of interface roughness and the abradable structure of the surface layer near the interface on the cracking of the composite coating were investigated. The cohesive zone model and the phase-field damage method were used to describe the overall peeling of cracks along the interface and the internal fracture behavior of abradable surface layer. Moreover, the peeling failure mechanism of coating was revealed. Results showed that the bonding strength and cracking tendency of the coating presented opposite change laws with the increase of interface roughness. On the one hand, the effective contact area of the non-damaging composite coating interface increased, and the bonding strength increased. On the other hand, with the increase of roughness, the internal fracture of the surface layer became easier. Therefore, the interface roughness should be optimized reasonably. In addition, the pore of surface layer near the interface could reduce the bonding strength at the interface. Based on this, an appropriate interface roughness was selected, and an anti-cracking compact transition layer was introduced between the thermal insulation layer and the abradable surface layer to eliminate the weakening effect of surface layer pores on the interface strength of composite coatings and design an anti-cracking coating.