Studies of the Microstructure and Properties of Dense Ceramic Coatings Produced by High-Velocity Oxgen-Fuel Combustion Spraying
A Kulkarni, J Gutleber, S Sampath, A N. Goland, W B. Lindquist, H Herman, Andrew J. Allen, B A. Dowdy
High-velocity oxygen-fuel (HVOF) spraying stands out among the various processes to improve metal and ceramic coating density and surface characteristics. This paper explores microstructure development, coating characterization and properties of HVOF sprayed alumina coatings and compares these with those produced using the conventional air plasma spray process. We report the characterization of these coatings using small-angle neutron scattering (SANS) and x-ray computed microtomography (XMT) to explain the behavior observed for the two coating systems. While microstructural information on porosity, orientation information and mean opening dimensions has been obtained using SANS, XMT has nondestructively imaged the microstructural features in 3-D at 2.7-mm spatial resolution over a 2 mm - 3 mm field of view. 3-D medial axis analysis has been used for the quantitative analysis of the void space in order to obtain information on the porosity, specific surface area, pore connectivity and size distribution in the coatings. The results reveal different pore morphologies for the two spray processes. While only globular pores are imaged in the plasma sprayed coating due to spatial resolution limits, the HVOF coating reveals highly layered porosity. These distinct microstructural features are correlated to the thermal and mechanical properties of the coatings.
, Gutleber, J.
, Sampath, S.
, Goland, A.
, Lindquist, W.
, Herman, H.
, Allen, A.
and Dowdy, B.
Studies of the Microstructure and Properties of Dense Ceramic Coatings Produced by High-Velocity Oxgen-Fuel Combustion Spraying, Material Science and Engineering A, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=850778
(Accessed December 11, 2023)