Determination on Interfacial Fracture Toughness of Thermal Barrier Coatings
A ceramic coating(topcoat)and a NiCoCrALY bondcoat were atmospheric-plasma-sprayed(APS)on a stainless steel substrate.A modified three-point bending test was adopted to initiate and propagate the topcoat/bondcoat(TC/BC)interfacial cracking.After a complete delamination,the fracture surfaces were examined by an optical microscope and a scanning electron microscope,which shows that the cracking plane was merely on the TC/BC interface.To obtain the crack length,the displacement and strain fields of the TC/BC cross-section were acquired using digital image correlation(DIC).Based on the experimental results,the critical strain energy release rate Gc for crack initiation was calculated with the Irwin-Kies formula,and the averaged magnitude was 77.1 J/m2.Moreover,the Gc for crack propagation was inversely determined by a finite element model to be in the range of 70-80 J/m2.Good agreement between theoretical and numerical results is evidenced indicating that the two methods can be used for the evaluation of interfacial fracture toughness in thermal barrier coatings and other multi-layer structures.
thermal barrier coatings three-point bending interfacial fracture toughness
Qi Zhu Wenfeng Hao Jianguo Zhu
Department of Mechanics and Engineering Science,Jiangsu University,Jiangsu 212013,China
国际会议
海口
英文
45-47
2018-01-12（万方平台首次上网日期，不代表论文的发表时间）