Ce-doped yttria-stabilized ZrO 2 (YSZ) fibers were prepared with different Ce concentrations (0, 5, 10, 20 mol%) by the sol-gel method. The effects of Ce addition on the microstructure and mechanical properties of the YSZ fibers have been investigated. Compared with the pure YSZ fibers, the Ce addition could cause grain refinement whose mechanism was discussed. Moreover, mechanical measurements showed that the Ce addition could increase the Young's modulus and microhardness of the YSZ fibers. When the doping content was 10%, the values of Young's modulus and microhardness were improved by almost 3 times and 2 times compared with those of the pure YSZ fibers, respectively. Results show that the Ce addition could improve the thermal insulation , thermal conductivity at 800 °C being reduced by over one third (33.52%) when the amount of Ce increased to 20%.
Yttria-stabilized zirconia (YSZ) fiber composites are highly efficient thermal insulating materials; however, the poor thermal shock resistance limits their versatile applications. In the present study, YSZ fiber was mixed directly with Al2TiO5 fiber, which had an extremely low thermal expansion coefficient, to prepare YSZ−Al 2 TiO 5 (ZAT) fiber composites by compression molding and heat treatment. The minimum thermal expansion coefficient of the prepared ZAT fiber composites was measured to be 7.74×10 −6 K −1 , which was 26% lower than that of the YSZ fiber composites (10.42×10 −6 K −1 ). It was shown that the prepared ZAT fiber composites maintain the integrity after undergoing 51 thermal shock cycles between 1100 °C and room temperature. Whereas, YSZ fiber composites burst immediately after only one thermal shock cycle under the same condition. In addition, the ZAT fiber composites also exhibit considerable mechanical and thermal insulating performance.
Guo Jin,Yongchao Fang,Xiufang Cui,Chang Wang,Dan Zhang,Xin Wen,Qingbo Mi
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.
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