Atmospheric　plasma　spraying　is　usually　accompanied　by　oxidation　reactions,　which　result　in　the　formation　of　oxides　in　the　coatings.　The　presence　of　oxides　in　metallic　coatings　is　usually　undesirable　because　they　cause　the　coating　properties　to　deteriorate.　This　study　highlights　how　the　high　temperature　oxidation　resistance　of　plasma　sprayed　NiCrCoAlY　coating　is　influenced　by　both　the　oxidation　behavior　of　NiCrCoAlY　particles　and　by　the　shrouding　gas　during　the　spray　process.　It　is　shown　that　two　different　oxidation　mechanisms　are　involved　in　the　in-flight　oxidation.　One　is　diffusion　oxidation,　and　the　other　is　convective　oxidation.　The　convective　oxidation　of　NiCrCoAlY　particles　is　the　dominating　oxidation　mechanism　when　the　plasma　jet　is　at　a　distance　of　55　mm　from　the　torch　nozzle　exit;　while　diffusion　oxidation　was　found　to　be　the　dominant　mechanism　when　the　spray　distance　is　greater　than　55　mm.　Oxidation　mainly　occurs　during　in-flight　and　after　impact　on　the　substrate.　In-flight　oxidation　is　the　dominant　mechanism　for　NiCrCoAlY　particles　in　plasma　spray.　Adding　inert-gas　shrouding　is　an　effective　method　for　decreasing　the　oxide　content　of　the　NiCrCoAlY　coating,　which　significantly　increases　the　coating＇s　oxidation　resistance.　(C)　2012　Elsevier　B.　V.　All　rights　reserved.