Second Step Approach for Self Healing Ceramics
Self healing of surface cracks is the most effective function to ensure the structural integrity for ceramic components, because even minute surface crack give rise to a large strength decrease because of its high sensitivity to flaws. The present author and coworkers succeeded that the degraded strength due to cracking can be completely recovered by self crack healing ability driven by the high temperature oxidation of silicon carbide. Then, the mechanism and the effect of the self-healing were investigated. The most attractive feature of the self healing is to be able to respond to the damage caused during service. Thus, enhancement in self healing velocity has been necessary to actualize the self healing ceramics. In the present study, nanometer sizing the disperse silicon carbide particle was attempted to achieve the purpose. Alumina composites containing various shapes of silicon carbide nanometer sized particles were synthesized from mullite, aluminum and carbon powders. From the strength recovery behaviors of these alumina/ silicon carbide composites, the following aspects were derived. Silicon carbide particles nanometer sizing can heal completely the surface cracks at lower temperature and shorter time.
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
W. Nakao "Second Step Approach for Self Healing Ceramics", Materials Science Forum, Vols. 638-642, pp. 2133-2137, 2010