Influence of Hydrogen on the Microstructure of Plasma-Sprayed Yttria-Stabilized Zirconia Coatings

Nanostructured YSZ thermal barrier coatings engineered to counteract sintering effects

“…As previously stated in Section 2.1, the conventional YSZ powder was spray-dried and plasma-densified forming the so-called hollow spherical powder (HOSP). SEM pictures of this type of HOSP powder can be found elsewhere [7,15].…”

“…It is important to point out that spray-dried and plasmadensified powders (conventional YSZ) are generally comprised of hollow or dense spherical powder particles [7,15]. The hollow particles will tend to exhibit a relatively dense outer shell facilitating heat transfer from the plasma jet to the inner part of the particles and thereby leading to more uniform heating and complete melting of the particle.…”

D.C. Plasma Spraying

“…The direction of injection can be perpendicular to the jet axis or at a positive or negative angle with respect to the perpendicular direction. Injection with a negative angle with respect to the injector axis (backward injection) can result in higher particle temperatures but somewhat lower particle velocities [45]. Internal injection requires careful adjustment of the carrier gas flow, too high flow rates will result in strong deflection of the plasma jet.…”

Sensing, Control, and In Situ Measurement of Coating Properties: An Integrated Approach Toward Establishing Process-Property Correlations

“…Some control the process at the hardware level and some at the in-flight particle level. Studies have suggested that control of particle state is better than simple hardware level control such as controlling total output power ( Ref 11,12). Another recent study has shown particle injection to be vital in achieving reliable particle state and in monitoring them reliably as well as in achieving reproducible coatings ( Ref 13,14).…”