Comparative Study of Silicate Coatings Fabricated by SPS and APS

Environmental barrier coating (EBC) have been developed and designed to protect ceramic matrix composites (CMC) of turbine parts. Recently, coated turbine parts by Barium Strontium Aluminum Silicate and Mullite are implemented on 1200 degree Celsius class gas turbine for aircraft. Ytterbium silicates have been developed for next generation aircraft gas turbine. Various coating properties such as density, thermal resistance, high temperature steam barrier and adhesion strength are required to achieve EBC function. On the other hand, suspension plasma spraying (SPS) have been developed for fabrication of several kinds of coatings which are suitable for gas turbine. Columnar structure coatings of YSZ have been investigated for next generation TBC. Dense coatings of SPS are considered to be great evolution of EBC fabricated by APS. In this study, SPS and APS silicate coating properties were investigated. In-flight particle properties and splat properties were investigated to understand difference of SPS and APS coating property. In conclusion, SPS coating structure was obviously advantageous compared to APS coating structure. However, crystal phase of SPS would be improve for EBC.