Self-healing plasma sprayed ceramic coatings

Tuesday, May 12, 2015: 8:20 AM
Room 101A (Long Beach Convention and Entertainment Center)
Ms. Z. Ilhan , German Aerospace Center (DLR), Stuttgart, Germany
Mr. V. Guski , University of Stuttgart, Stuttgart, Germany
Dr. Noriko Sata , German Aerospace Center (DLR), Stuttgart, Germany
Dr. Aitor Hornes , German Aerospace Center (DLR), Stuttgart, Germany
Dr. U. Weber , University of Stuttgart, Stuttgart, Germany
Mr. Oliver Freitag , German Aerospace Center (DLR), Stuttgart, Germany
Dr. Axel Krebs , University of Stuttgart, Stuttgart, Germany
Dr. Günter Schiller , German Aerospace Center (DLR), Stuttgart, Germany
Prof. S. Schmauder , University of Stuttgart, Stuttgart, Germany
Prof. Andreas Friedrich , German Aerospace Center (DLR), Stuttgart, Germany
Dr. Asif Ansar , German Aerospace Center (DLR), Stuttgart, Germany
Self-healing in plasma sprayed MgAl2O4 coatings was examined. Self-healing additives consisting of SiC+X (X was anyone of BaO, CaO, ZnO, Y2O3,GeO2, Ta2O5, V2O5) were characterized using TGA, HT-XRD and Raman Spectroscopy. Based on its reaction temperature, low toxicity and compatibility with neighbouring components, SiC+Y2O3 was selected and coatings were developed using vacuum and atmospheric plasma spraying. The coatings revealed healing after thermal treatment at 1000°C in air after 1 hour; 5 hour dwell improved the healing. CTE and electrical resistivity of the coatings decreased as a function of additive content. The Young’s moduli and fracture strength of the coatings were tested by 4-point flexural tests. In addition, a modelling technique was developed that determined the Young’s modulus by comparing the force-displacement curves of a simulated 4-point bending test with experimental ones. Assuming fracture mode I, the principal stress criterion for the ceramic was implemented in a cohesive zone model determining the fracture energy of the ceramic layer. The numerical results showed good consistence with experimental data.
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