Ytterbium Silicate EBCs by Solution Precursor Plasma Spray and a few other things about SPPS

Ytterbium Silicate EBCs by Solution Precursor Plasma Spray and a few other things about SPPS Eric H. Jordan, Chen Jiang, Rishi Kumar Solution Spray Technologies LLC. Air plasma spray of ytterbium silicate EBCs typically results in a mixture of mono- and di-silicates due to the heterogeneous nature of the process. In solution precursor plasma spray (SPPS), mixed phases are also produced however the resulting coatings are more phase pure and the secondary phase domain size is smaller. Due to the difference in expansion coefficient of mono and disilicates the secondary phase will be significantly stressed. In the case of the primary phase is monosilicate having the higher CTE, cooling should lead to tension in the disilicate. Smaller secondary phase domains will have less local strain energy which is desirable. In addition to discussing the above, two features possible with the SPPS process will be briefly discussed, (1) the ability to make significantly dense and hard surfaces and (2) the ability to produce by polishing very smooth surface likely due to the fine scale of the splat structure of the SPPS coatings.