Synthesis of alumina and aluminum nitride layers on a graphitic substrate via a sol-gel route

Abstract

In this study, our objective is to deposit an alumina or an aluminum nitride layer on a turbostratic carbon substrate. The coatings are synthesized via a sol-gel route followed by a heat treatment in order to obtain α-alumina or hexagonal aluminum nitride by carbothermal nitridation of alumina. The synthesis of such layers on carbon substrates is not reported in literature.
Several slurries were elaborated using various solvents and catalysts, and aluminum-tri-secbutoxide as an aluminum precursor. The coating is obtained by dropping the substrate in the sol. After drying and pyrolysis, the amorphous alumina layer obtained has a thickness ranging from 500 nm to 1 μm. The material is finally heat treated. Several treatment conditions were evaluated.
A thermodynamic study of the Al-C-O-N system will be drawn, and the composition of the synthesized sol-gel and heat treatment parameters will be detailed. Then, the layer’s morphology and structure will be characterized thanks to Scanning Electron Microscopy and X-Ray Diffraction analyses. The impact of heat treatment parameters will be discussed and experimental results will be compared to the theoretical thermodynamic results.