In: Other
What's the objective of precursor preparation experiment?
And why the color of precursors changes during the experiment?
Solution precursor plasma
spraying (SPPS) presents a modern route to deposit coatings
directly from liquid feedstock. In this study, unique ability of
SPPS to intermix different precursors on the atomic scale was
employed to deposit pure and Cr-doped Al O (technically, synthetic
ruby) from several mixtures of aluminum and chromium nitrates.
Highly porous coatings (> 60% porosity) were deposited by
high-enthalpy WSP-H torch. Homogeneous distribution of Cr atoms in
Al O resulted in coatings color ranging from pink to grayish-green
correlated with increasing Cr content and change of lattice
parameters as observed by x-ray diffraction. High content of over
80 wt.% of α-alumina phase was reached for all coatings. For the
Cr-doped Al O coatings, distinct and fully reversible thermochromic
behavior was observed by temperature-resolved colorimetry. Further
increase in α-phase content (up to 95 wt.%) and coating
densification were achieved by additional surface remelting by
plasma torch.