Oxidation-induced Crack Healing in MAX Phase Containing Ceramic Composites

Book chapter (2016)

Authors

G. Bei Friedrich-Alexander-Universität Erlangen-Nürnberg, (OLD) MSE-1
Peter Greil Friedrich-Alexander-Universität Erlangen-Nürnberg
Research Group
(OLD) MSE-1
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Published Date

2016

Language

English

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Research Group

(OLD) MSE-1

Abstract

Crack healing in MAX phase-based ceramics is mainly attributed to the reaction of M and A metal with oxygen penetrating into the crack. The intrinsic healing mechanisms of Al-contained MAX phases are due to formation of adhesive Al2O3 phase in the crack gaps, while Sn-contained MAX phases are ascribed to formation of major TiO2 and SnO2 in the bigger crack gaps and metallic Sn formation in the smaller secondary cracks. The oxides as well as metallic phase filling the crack may restore the integrity of MAX phase ceramic components. The mechanical strength and the electrical conductivity of the MAX phase ceramics can be fully restored after the healing process. The remarkable healing abilities of those MAX phases make them promising repair fillers for those ceramics with poor healing ability. Al2O3 mixed with Ti2Al0.5Sn0.5C MAX phase was selected as a model to demonstrate the healing efficiency. The fracture strength of 20 vol.% repair filler composites containing artificial indent cracks recovered fully to the level of the virgin material upon isothermal annealing in air atmosphere after 48 h at 700 °C and 0.5 h at 900 °C. The evolution of the crack-filling microstructure was explored by X-ray powder diffraction and transmission electron microscopy analyses.