High deposition rate coating with nanodisperse SiC powder by plasma-assisted pulse pyrolysis

Abstract

With regard to the development of a high deposition rate coating process at low substrate temperatures, we investigated whether this can be realized by the formation of nanodisperse SiC particles and their deposition in a one-step process. The SiC powders were obtained by plasma-assisted pyrolysis of tetramethylsilane (TMS) as particle precursor. Owing to a reduction in the amount of particles and the prevention of substrate heating, the particles were formed by pulse pyrolysis at temperatures of 1200–2000 K and at pulse times of 0.1–4 ms. The investigations were performed by means of a shock tube. The powders obtained are nanodisperse with particle sizes in the range below 40 nm consisting of variable contents of both amorphous SiC and crystalline β-SiC. The powders form very thin layers; a single pulse generates a layer with a thickness in the range 40–80 nm, determined by ellipsometric measurements. The layers adhere on the substrate but because of a lack of deposition energy their solidity and adherence on the substrate are not sufficient. Investigations were performed to increase the solidity of the layers by subsequent energy transfer to the layer.