Characterisation of thermally sprayed coatings
Ooi, Thian Ngan.
Date of Issue1997
School of Applied Science
Thermally sprayed coatings have some of the most complex microstructures tbund in Material Science. The multifaceted structures comprise lamellae splats, non-metallic inclusions, micro and macropores as well as unfused particulates. The extent of this microstructural inhomogenity is expected to exert considerable influence on coating properties. The use of Backscattered Electron Modal Analysis (BEMA) provides a fast and convenient alternative to perform quantitative analysis on the microstructure of plasma sprayed coatings. Sufficiently good elemental discrimination can be achieved because of the sensitivity of backscattered electrons (BE) to atomic number variations. Variations in the percentage of oxides. holes and phases as a result of different spraying conditions or powder characteristics are generally observable from the spatial profile of BE spectrum. The ability to detect minute microstructural variations as a function of spray parameters provides a promising technique of optimizing the quality of thermally sprayed coatings.
NANYANG TECHNOLOGICAL UNIVERSITY