Physics Journal of the Indonesian Physical Society
CRYSTALLOGRAPHIC PREFERRED ORIENTATION AND PHASE FRACTION OF PLASMA SPRAY COATINGS BY MEANS OF NEUTRON AND X-RAY DIFFRACTION
Husin Sitepu1, J.K. Stalick2, H.J. Prask2, M.D. Vaudin3 and S. Sampath4
1FaME38 at ILL ESRF, BP 156, F-38042 Genoble Cedex 9, France
2NIST Center for Neutron Research, Gaithersburg MD 20899, USA
3NIST Ceramic Devision, Gaithersburg, MD 20899, USA
4SUNY Center for Thermal Spray Research, Department of Materials Science and Engineering, Stony Brook, NY 1179, USA
In the present study the generalized spherical harmonic description was used to determine the degree of crystallographic preferred orientation (or texture) in nickel plasma-sprayed coatings using two procedures. The first procedure used the popLA software (Kallend et.al., 1991) to determine the texture index of the various nickel coatings. Neutron diffraction pole-figure data were measured using the NIST four-circle goniometer on the DARTS diffractometer. The second procedure involved the GSAS (Larson and Von Dreele, 2000) Rietveld refinement program. X-ray diffraction data were collected using the D500 Bragg-Brentano instrument equiped with position sensitive detector. The results indicate that the degree of texture derived from Rietveld refinement with generalized spherical harmonic description agrees quite satisfactorily with the calculated value obtained directly from measured pole-figures for various nickel coatings. In addition, neutron diffraction data of plasma-sprayed 8wt% yttria stabilized zirconia coatings deposited at 75oC and 300oC have been carried out using the BT-1 high-resolution fixed-wavelength 32-detector powder diffractometer at the NIST Center for Neutron Research. The results derived from Rietveld refinement with generalized spherical harmonic description for each plasma yttria stabilized coating data set show that the major phase is tetragonal while the weight percentages of the monoclinic phases are (1.54±0.41)% and (3.71 ±0.94)% for the cold and hot substrate samples, respectively.