Effects of particle dispersion on the properties of suspension-sprayed coatings

Abstract

Suspension spraying is a promising surface modification technique, because finer particles can be used in contrast to the case of conventional thermal spraying. However, the optimal conditions for preparing suitable suspensions have not yet been established. Thus, the effects of particle dispersion and flocculation states on the properties of suspension-sprayed coatings were examined in the present study. Y 2 O 3 suspensions were prepared using various quantities of the dispersant. The flow curves and gravitational settling behaviors of the prepared suspensions were investigated. The amounts of the dispersant adsorbed on the particles were also determined. In addition, Y 2 O 3 coatings were fabricated using suspension spraying, and the properties of the obtained coatings were investigated. The addition of the dispersant affected the suspension flow characteristics, because the amount of the dispersant adsorbed increased with increasing dispersant concentration. Furthermore, the coating characteristics improved as the apparent viscosity of the suspension decreased.

Determination of optimum slurry evaluation method for the prediction of BaTiO3 green sheet density

“…It is considered that the particles flocculated and formed gelation structure due to the sedimentation concentration at that point, after maintaining the same dispersion state from the beginning. The same phenomena were confirmed in previous works [11][12][13][16][17][18]…”

“…This method can distinguish the difference in sedimentation rate that depends on the particle dispersion state. It has also been used to effectively measure dense slurries directly [11][12][13][14][15][16][17][18]. However, it was not confirmed whether the results are correlated with the green body density.…”

Effect of medium condition change on green body density during casting and drying

“…We have proposed a slurry evaluation technique using a hydrostatic pressure method based on the particle sedimentation phenomena reported in several studies 24–32 . Additionally, in a previous study, this technique was applied to an aqueous dense barium titanate slurry, which demonstrated that the relationship between the measurement result and packing fraction of green sheet had a better correlation than other slurry evaluations 32 .…”