Ceramics-Silikáty 42 (3) 81-89 (1998)

USE OF SMALL-ANGLE NEUTRON SCATTERING FOR THE CHARACTERIZATION OF ANISOTROPIC STRUCTURES PRODUCED BY THERMAL SPRAYING

J. Ilavsky, G. G. Long, A. J. Allen, H. Herman, C. C. Berndt

Results for the microstructural characterization of thermal spray deposits, using small-angle neutron scattering (SANS), mercury-intrusion porosimetry, and image analysis of polished cross sections, are compared. The alumina and yttria-stabilized zirconia deposits studied were produced by two different atmospheric plasma-spraying methods - using gas-stabilized and water-stabilized plasma systems. The void microstructure of these deposits is dominated by two anisotropic void types - interlamellar pores and intralamellar cracks. There is also a broad distribution of spherical pores. The relative importance of these void systems is found to depend on the materials chemistry and on the spray technique. The surface area of the anisotropic voids was determined using SANS. By varying the spray technique and material, deposits with different dominant void systems were produced. The alumina deposits, manufactured by a high-power water-stabilized plasma-spray system, consisted of a microstructure dominated by intralamellar cracks; the same material deposited by a standard lower-power gas-stabilized plasma-spray system has about equal surface area in the intralamellar cracks and interlamellar voids. However, the zirconia deposit microstructure is always dominated by inerlamellar voids.

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