Study on formation mechanism of YSZ thermal barrier coatings with segmented structure

Compared with traditional structures, YSZ TBCs with high segmentation crack density sprayed have exhibited a promising potential in improving TBC thermal shock resistance because the segmentation cracks increase its strain tolerance. A study is presented of formation mechanism of segmented TBC. The segmentation cracks initiate and propagate during the deposition phase, as a result of stress relaxation when the coating is subjected to tensile stress. Also, the crack density reaches a constant value and is not influenced by further plastic deformation of the metal. High heat input to the substrate is the most favorable factor in developing segmentation cracks because particle temperature promote the joining of adjacent lamellae.