Effect of YSZ fibers and carbon nanotubes on bonding strength and thermal cycling lifetime of YSZ-La2Zr2O7 thermal barrier coatings

In this work, the YSZ fibers and multi-walled carbon nanotubes (MWCNTs) were respectively employed as the extra additive to make some effect to improve the mechanical and thermal properties of YSZ-La 2 Zr 2 O 7 double-layer (LZ) thermal barrier coatings (TBCs). The porosity, thermal conductivity , bonding strength , fracture toughness and thermal cycling behavior of coatings were tested and discussed. The results showed that the addition of YSZ fibers and MWCNTs could improve the properties of LZ coating. In particular, the LZ coating exhibited lower thermal conductivity than that of YSZ coating with single-layer. Compared with MWCNTs reinforced LZ coating, YSZ fibers reinforced coating showed the lowest thermal conductivity and highest bonding strength value, due to the outstanding reinforcement of fibers. In contrast, the LZ coating containing MWCNTs presented the highest fracture toughness value and the best thermal cycling behavior than those of LZ coating and LZ coating containing YSZ fibers, which were attributed to the lowest porosity existing in LZ coating with MWCNTs, contributing to the remarkable inhibition of crack propagation . Therefore, the addition of YSZ fibers and MWCNTs was expected to be a potential way to improve the mechanical and thermal properties of LZ-TBCs.