关键词:
thermal barrier coatings
rare earth tantalates
nano indentation
fracture toughness
mechanical properties
摘要:
Comprehensive mechanical properties, including hardness (H), elasticity modulus (E), fracture toughness (KC), and wear resistance, are essential for various oxide ceramics based on their demanding working environments. In this work, the nano indentation is used to thoroughly estimate the above properties of RE3TaO7 (RE=La, Sm, Eu, Gd, Dy, Lu), and we identify the best calculation method of KC for brittle oxide ceramics. It turns out that the length ratio between indentation and cracks (l/alpha) is a key parameter to choose the calculation method, while the indentation indication energy method is not suitable for brittle oxide ceramics due to the existence of cracks. Furthermore, RE3TaO7 oxides exhibit high H (5.8-14.9 GPa) and E (127.5-247.8 GPa), and their KC (1.0-2.0 MPa m1/2) is higher than those of RE2Zr2O7 (1.0-1.5 MPa m1/2), which are good for their high-temperature applications. This work summarizes accurate calculation methods for mechanical properties based on nano indentation, and they can be used for various oxide ceramics. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(H),(sic)(sic)(sic)(sic)(E),(sic)(sic)(sic)(sic)(KC)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)RE3TaO7(RE=La, Sm, Eu, Gd, Dy, Lu)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic): (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(l/alpha)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic), RE3TaO7(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(5.8-14.9 GPa)(sic)(sic)(sic)(sic)(sic)(sic)(127.5-247.8 GPa), (sic)(sic)(sic