Gas jet assisted vapor deposition of yttria stabilized zirconia
Experimental setup used for the deposition of partially stabilized zirconia (containing yttria) on platinum modified nickel aluminied coated IN100 substrates at a temperature of .
Schematic illustration defining the parameters used to quantify the morphology of the porosity found in 7 YSZ coatings.
SEM micrographs showing (A) the cross section and (B) the top surface of a 7 YSZ coating deposited using a chamber pressure of and a pressure ratio of 10.0. Note the intercolumnar pores that extend from the substrate to the coating surface.
Plot showing the change in (A) the intercolumnar pore width and (B) the intercolumnar pore spacing with chamber pressure. Note the systematic increase in both parameters as the chamber pressure increased.
Plot showing the measured change in (A) the total pore volume fraction and (B) the intercolumnar pore volume fraction in YSZ coatings deposited using a range of chamber pressures . Note the dramatic increase in pore volume fraction as the chamber pressure increased. The difference between the curves in (A) and (B) is a measure of the intracolumnar pore volume fraction.
High magnification SEM micrograph showing cross sections of zirconia coatings deposited using (A) a chamber pressure of and a pressure ratio of 10.0 and (B) a chamber pressure of and a pressure ratio of 2.5. Note the smoother and denser appearance of the low pressure condition and the porous, granular appearance of the high pressure case.
XRD data showing the change in the relative intensity of the (200) peak with respect to the (111) peak. High (200) peak intensities indicate the presence of a (200) preferred orientation. Note the increased (200) peak intensity as the chamber pressure was decreased.
DSMC simulations showing the speed of a helium-3.0% oxygen carrier gas in (A) the axial direction and (B) the radial direction. The axial component was reduced in the region near the substrate and significant radial component developed (i.e., the wall jet).
Change in the IAD distribution with chamber pressure is given. Higher chamber pressures resulted in broader distributions and peak positions close to the substrate normal.
Change in the peak dispersion width with chamber pressure is given. The anticipated effect of cluster formation on is schematically shown.
Estimate of the cluster size for a range of zirconia hard sphere diameters. Increased chamber pressures and larger hard sphere diameters result in larger cluster impacts.
Schematic illustration showing (A) atomistic deposition onto a rough substrate resulting in the nucleation of intercolumnar porosity and (B) cluster deposition onto a rough substrate. The clusters shown are of the same size scale as the substrate roughness leading to the inability to result in shadowing induced pore nucleation.
Schematic illustration showing the effect of the IAD on the width of intercolumnar pores.
DVD process conditions employed.
Pore parameters for each pressure condition.
Relative peak intensities from XRD patterns of the yttria stabilized zirconia films deposited with different chamber pressures.
DSMC simulation results for the gas jet expansion and IAD distribution.
Input values for the cluster size calculations.
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