Effect of Phase Structure Evolution on Thermal Expansion and Toughness of (Nd1-xScx)2Zr2O7 (x = 0, 0.025, 0.05, 0.075, 0.1) Ceramics

Abstract

Abstract:

Nd₂Zr₂O₇ is being explored as an alternate thermal barrier coating (TBC) material for operating above 1300?°C, and great effort has been made to enlarge its thermal expansion coefficient (TEC) and improve its toughness. In this study, Sc₂O₃ was doped to Nd₂Zr₂O₇. The phase structure, TECs and toughness of (Nd_1-_xSc_x)₂Zr₂O₇ (x?=?0, 0.025, 0.05, 0.075, 0.1) compounds were investigated. (Nd_1-_xSc_x)₂Zr₂O₇ (x?=?0, 0.025, 0.05, 0.075) exhibited pyrochlore structure, while (Nd_0.9Sc_0.1)₂Zr₂O₇ consisted of pyrochlore and fluorite phases. With the increase of the Sc₂O₃ content, the ordering degree of the pyrochlore in the compounds decreased. In (Nd_1-_xSc_x)₂Zr₂O₇ series, (Nd_0.925Sc_0.075)₂Zr₂O₇ exhibited the largest TEC, while the toughness of the compounds increased with increasing the Sc₂O₃ content. The related mechanisms were discussed based on the crystal structure analysis. Considering the TEC and toughness, 10?mol% Sc₂O₃ was suggested as the optimal doping content for Nd₂Zr₂O₇ ceramic.

Key words: Thermal barrier coating, Nd2Zr2O7, Doping, Phase structure, Thermal expansion coefficient

Zhao Xiaoxiang,Guo Lei,Wang Caimei,Zhang Yu,Ye Fuxing. Effect of Phase Structure Evolution on Thermal Expansion and Toughness of (Nd1-xScx)2Zr2O7 (x = 0, 0.025, 0.05, 0.075, 0.1) Ceramics[J]. J. Mater. Sci. Technol., 2017, 33(2): 192-197.

Figures/Tables 10

Fig.1 XRD patterns of (Nd1-xScx)2Zr2O7 ceramics

Fig.2 Lattice parameters of (Nd1-xScx)2Zr2O7 ceramics as a function of x value

Fig.3 Thermal expansion rate of (Nd1-xScx)2Zr2O7 ceramics

Fig.4 The average TECs of (Nd1-xScx)2Zr2O7 ceramics

Fig.5 Raman spectra of (Nd1-xScx)2Zr2O7 ceramics

Fig.6 Results of Rietveld refinements of x?=?0.05 in (Nd1-xScx)2Zr2O7

Fig.7 Results of Rietveld refinements of ɛ-parameter of 48f oxygen

Fig.8 Microstructure of (Nd0.925Sc0.075)2Zr2O7 bulk

Fig.9 Vickers indentation SEM image of (Nd0.925Sc0.075)2Zr2O7 bulk

Fig.10 Vickers hardness and fracture toughness values of (Nd1-xScx)2Zr2O7 ceramics

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