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. 2017 Mar 21:7:44922.
doi: 10.1038/srep44922.

Unprecedented simultaneous enhancement in damage tolerance and fatigue resistance of zirconia/Ta composites

A Smirnov  1   2 , J I Beltrán  1 , T Rodriguez-Suarez  3 , C Pecharromán  1 , M C Muñoz  1 , J S Moya  1   4 , J F Bartolomé  1
Affiliations

Unprecedented simultaneous enhancement in damage tolerance and fatigue resistance of zirconia/Ta composites

A Smirnov et al. Sci Rep. .

Abstract

Dense (>98 th%) and homogeneous ceramic/metal composites were obtained by spark plasma sintering (SPS) using ZrO2 and lamellar metallic powders of tantalum or niobium (20 vol.%) as starting materials. The present study has demonstrated the unique and unpredicted simultaneous enhancement in toughness and strength with very high flaw tolerance of zirconia/Ta composites. In addition to their excellent static mechanical properties, these composites also have exceptional resistance to fatigue loading. It has been shown that the major contributions to toughening are the resulting crack bridging and plastic deformation of the metallic particles, together with crack deflection and interfacial debonding, which is compatible with the coexistence in the composite of both, strong and weak ceramic/metal interfaces, in agreement with predictions of ab-initio calculations. Therefore, these materials are promising candidates for designing damage tolerance components for aerospace industry, cutting and drilling tools, biomedical implants, among many others.

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Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1
Scanning electron images corresponding to the microstructure of (A) zirconia/Ta and (B) zirconia/Nb composites. Darker and lighter phases are zirconia and the corresponding metal, respectively.
Figure 2
Figure 2. High resolution transmission electron micrograph of the ZrO2/Ta interface.
Figure 3
Figure 3. Indentation load versus strength plots of 3Y-TZP/Ta, 3Y-TZP/Nb composites and zirconia ceramic.
The indentation-strength data to the P−1/3 strength response is shown by the diagonal dashed line.
Figure 4
Figure 4. Fatigue resistance S–N curves with values of slopes for un-indented polished specimens.
Figure 5
Figure 5. Fracture surfaces of SPSed ZrO2/Nb (A, C) and ZrO2/Ta (B, D) composites after bending and fatigue test, respectively.
Black arrows show marks of rounded grains debonded from the brittle zirconia matrix. White arrows show decohesion between the matrix and the metallic particles. Dashed black arrows show the cleavage of metallic particles.
Figure 6
Figure 6. FIB-SEM image of crack propagation in the zirconia-tantalum composite.
Arrows indicate interface debonding between the metal particles and the ceramic (A), plastic deformation (B) and crack bridging of ligament (B).
Figure 7
Figure 7. Composites’ fracture surface 3D images and corresponding roughness values (Ra, μm) after biaxial bending (A – ZrO2/Ta and C – ZrO2/Nb) and fatigue (B – ZrO2/Ta and D – ZrO2/Nb) tests.
Figure 8
Figure 8. S–N plot of the cycles to failure (N) of indented ZrO2, ZrO2/Ta and ZrO2/Nb composites.
Ultimate flexural strength of un-indented specimens is plotted as well.
Figure 9
Figure 9. Number of cycles and crack length as a function of the applied load for ZrO2 (top), ZrO2/Nb (middle), and ZrO2/Ta (bottom) composites.
See this image and copyright information in PMC

References

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