Inhibition of the formation of the B metastable phase in yttrium oxide plasma-spray coatings by the addition of zirconia
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Yttrium oxide plasma-spray deposits show a metastable B phase together with the cubic stable form. This B form is prejudicial for thermal applications of these coatings (i.e. weakens mechanical properties, etc.). Attempts have been made to avoid the formation of this metastable phase during the plasma-spraying operation by use of an inhibitor, such as ZrO2. A large solid solution with cubic C phase was found to form between ZrO2 and Y2O3 (Y1−xZrxO1.5 + x/2 □ 0.5 − /2). A method is described for preparing powders suitable for plasma spraying. Several compositions were tested. B phase is no longer formed for ZrO2 additions as low as x = 0.03. The influence of ZrO2 addition on Y2O3 coatings properties is discussed.
KeywordsOxide Polymer Mechanical Property Zirconia Solid Solution
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