Influence of plasma spray parameters on in-flight characteristics of ZrO2-8 wt% Y2O3 ceramic particles

Yttria-partially-stabilized zirconia was atmospherically plasma sprayed by systematically varying the process conditions including carrier gas flow ra te, torch power, standoff distance, and Ar/H-2 ratio in the plasma gas mixt ure. The in-flight particle parameters such as temperature, velocity, numbe r, and size were determined using a commercially available diagnostic syste m. The particle parameters were controlled by the particle trajectory in th e plume and plasma jet characteristics. The average temperature and the vel ocity of particles, which reached their maximum at an intermediate carrier gas flow rate of 3.5 L/min, varied as much as 6% and 25%, respectively, wit h a 75% variation in the carrier gas flow rate by going from the lowest to the intermediate rates. The average temperature and the velocity of particl es were lower for a lower torch power, a higher Ar/H-2 ratio, and a larger standoff distance. It was necessary to obtain data on particle populations larger than 1000 for statistically reliable and reproducible information fr om the diagnostic system.