Acoustic　emission　(AE)　monitoring　was　used　during　indentation　tests　on　the　cross　section　of　plasma-sprayed　8 wt.%　yttria-stabilized　zirconia　(8YSZ)　thermal　barrier　coatings　to　investigate　the　relationship　between　AE　signals　and　the　associated　deformation　or　single　cracking　events.　The　damage　evolution　in　8YSZ　was　studied　by　examining　signal　characteristics　with　the　aid　of　AE　parameter　analysis　and　wavelet　packet　decomposition.　The　results　show　that　the　coatings　were　firstly　elasto-plastically　deformed,　and　microcracks　gradually　developed　around　the　indentation.　Then,　delamination　occurred　and　the　fracture　was　made　up　of　some　longer　cracks　and　dozens　of　microcracks.　AE　signals　originating　from　coating　deformation,　formation　of　microcracks　and　longer　cracks　show　different　amplitudes　and　frequencies.　The　results　indicate　that　the　features　of　AE　parameters　differ　depending　on　the　mechanical　failure　mechanism,　and　AE　responses　are　closely　related　to　the　fracture　behavior　and　are　dependent　on　splat　microstructure　of　the　coatings.　©　2019,　ASM　International.