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.