Development of AlN-Al2O3 composite coatings via high velocity suspension flame spraying (HVSFS)
Development of AlN-Al2O3 composite coatings via high velocity suspension flame spraying (HVSFS)
Ebru Gyoktepeliler-Akin1, Matthias Blum1 and Andreas Killinger1
1Institut für Fertigungstechnologie keramischer Bauteile (IFKB), University of Stuttgart, Allmandring 7b, D-70569, Stuttgart, Germany
In applications such as electronics and optoelectronics, where high heat exchange performance is required, the thermal conductivity of alumina is not always sufficient. Aluminium nitride, with higher thermal conductivity as well as higher electrical resistivity, is favourable alternative to alumina. Therefore, the present study is focused on fabrication of AlN-Al2O3 composite coatings by HVSFS process using aqueous suspensions containing Al2O3, AlN powders and mixtures of AlN and Al2O3 as feedstock materials. The suspensions were deposited on steel substrates in various combinations of axial and radial injection, and a parameter study was performed to optimize the coating properties.
The composite coatings were characterised regarding their phase composition, microstructure, mechanical and physical properties. The aim is to develop coatings with high AlN content and thus higher thermal conductivity. A significant improvement in thermal conductivity was observed in the case of AlN and AlN-Al2O3 composite coatings, and the values correlate with the AlN content.