%0 Journal Article
%T Crack Growth Tests in Air Plasma-Sprayed Yttria Coatings for Alumina Ceramic Matrix Composites
%J Ceramics | An Open Access Journal from MDPI
%D 2019
%R https://doi.org/10.3390/ceramics2030039
%X Yttria coatings for all-oxide combustor walls were tested for their crack-growth behavior. These environmental and thermal barrier Y2O3-coatings were processed by atmospheric plasma spraying (APS). The stiffness and strength were measured for as-received and aged samples that were heat treated at 1000 ˇăC, 1100 ˇăC and 1200 ˇăC for a 10 h dwell time. The results show a clear development with respect to the aging conditions. The changes of the modulus and the bending strength indicate that the microstructural changes are not completed, even after aging at 1200 ˇăC for 10 h. The fracture toughness was tested for different orientations on samples aged at 1200 ˇăC. Bending tests as well as indentation experiments were conducted. Furthermore, a bending device was designed to observe the crack-growth in situ. The device had to be rigid and is driven by a piezo stack. The crack growth resistance shows differences in the rise of the R-curves for different orientations of the crack propagation. This is in agreement with the microstructure that results from the plasma spray process. View Full-Tex
%U https://www.mdpi.com/2571-6131/2/3/39