In Situ Characterization of Small-Particle Plasma Sprayed Powders

Abstract

The effect of various small-particle plasma spray powder injection parameters on the in situ particle position, velocity, and temperature is measured for yttria-stabilized zirconia and yttrium-aluminum-garnet powder. Using full-factorial experiments and multiple regression analysis, carrier gas flow, injector angle, and powder feeder disc speed were found to significantly affect the particle properties. Temperature and velocity were inversely related; on average, the cooler particles traveled faster. These properties also correlated to the particle position in the flame, where particles above the centerline of the flame traveled faster. The trends are discussed on the basis of residence time in the flame, as well as in terms of particle size segregation effects. Coating density and splat geometry reflect the temperature and velocity differences between the runs. Slower, hotter particles possessed more intrasplat and intersplat porosity and less splat-substrate contact area, leading to lower overall coating density.

Through-thickness determination of phase composition and residual stresses in thermal barrier coatings using high-energy X-rays

“…Substrates were rinsed in isopropanol and dried prior to spraying. A small particle plasma spray injector with a 40°injection angle was used for the deposition of a 300-lm-thick YSZ topcoat [32,33]. Coated substrates were cross-sectioned to produce samples $25 Â 4 Â 2.5 mm.…”

Tantalum Oxide Coatings as Candidate Environmental Barriers

“…This allows powders to be entrained in the outer isotherms of the plasma stream and efficiently be deposited onto the substrate. [21] SPPS was developed to increase coating quality, in particular density, through the use of smaller powders with particles less than 10 µm. For the second round of experiments both a straight (zero angle) and the SPPS injector were used.…”

Influence of in-flight particle state diagnostics on properties of plasma sprayed YSZ-CeO2nanocomposite coatings

“…The important control parameters in plasma spraying are the flow rates of plasma and powder carrier gas, torch input power, dwell time and powder feed rate. There have been a few reports regarding the studies on structural, micro-structural, thermal and mechanical properties by controlling particle temperature and velocity [13][14][15]. However, optimum spray conditions which would yield required physical and mechanical properties have not been identified.…”