Measurements of elastic modulus and fracture toughness of an air plasma sprayed thermal barrier coating using micro-cantilever bending

SURFACE & COATINGS TECHNOLOGY

卷:374

Article

Chen, Ying^1,4  Zhang, Xun^1,5  Zhao, Xiaofeng²  Markocsan, Nicolaie³  Nylen, Per³  Xiao, Ping^1,2 

[1] Univ Manchester, Sch Mat, Manchester M13 9PL, Lancs, England

[2] Shanghai Jiao Tong Univ, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R China

[3] Univ West, Dept Engn Sci, Trollhattan, Sweden

[4] OxMet Technol, Oxford OX5 1PF, Oxon, England

[5] Univ Oxford, Dept Engn Sci, Parks Rd, Oxford OX1 3PJ, England

关键词: Elastic modulus;    Fracture toughness;    Micro-cantilever bending;    Microstructure;   

DOI  :  10.1016/j.surfcoat.2019.05.031

来源: Elsevier

【 摘 要 】

The elastic modulus and fracture toughness of an air plasma sprayed thermal barrier coating (APS TBC) were measured using the micro-cantilever bending technique. The micro-cantilevers were machined by a focused ion beam with their central arms either parallel or normal to the bond coat/topcoat interface. Such orientations allowed direct measurements of both the in-plane and out-of-plane elastic moduli as well as mode I fracture toughness by bending. The calculated elastic modulus along the in-plane and out-of-plane direction is similar to 144 GPa and similar to 110 GPa, respectively, suggesting that the APS TBC is elastically anisotropic at microscale. The derived mode I fracture toughness along the plane parallel to the interface is similar to 0.40 MPa root m. This relatively low toughness reflects the weak fracture resistance of the highly-flawed APS for short cracks at microscale. The measurements in this study can be incorporated into micromechanical life time prediction models of the APS TBCs.

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