Thin film coating of nano-particles in a capacitively coupled RF discharge
Other titre : Déposition de couches minces sur nano-particules par plasma RF à couplage capacitif
Presently, nanocomposite materials have numerous applications, especially in the fields of materials for electronics, aerospace industry, biotechnologies and medicine. Utilization of plasma technologies can offer new production methods of such materials, in particular, the use of non-thermal plasmas for the treatment of hydrocarbons, which makes it possible to obtain a wide variety of thin films with a range of different characteristics. The goal of the presented thesis is an application of the non-thermal plasma for the fabrication of nano-structured materials on the basis of ceramic nanopowders (SiO[subscript 2], TiO[subscript 2]) introduced into the plasma of hydrocarbon gases. For this purpose an experimental installation with a capacitively coupled plasma (CC RF) has been designed and constructed. The operating parameters are: the plasma pressure, P = 1000-10 000 Pa, plasma power: 300-2500 W (specific power: 2-20 W/cm[superscript 3]), plasma gas flow rate: 0.01-0.1 slpm. Nanometric particles of SiO[subscript 2], either TiO[subscript 2] were introduced into CC RF methane or ethane plasmas to perform the deposition of thin film hydrocarbon coatings onto their surfaces. The presence of newly formed 5-30 nm thick layers on the surface of the plasma treated particles was detected by TEM. The analysis of these coatings by infrared spectroscopy, thermo-gravimetry, differential scanning calorimetry, has demonstrated the features of amorphous hydrocarbon coatings (a-C:H). No contamination of the product powder by amorphous carbon was detected. The reproducibility of the process has also been demonstrated. The main original contributions of the present thesis may be presented as: (1) the design and construction of the capacitively coupled low pressure RF plasma facility, this being able to provide in-flight treatments of the introduced nanoparticles, and which may be integrated in series into a more complex, technological process. (2) the development of the process for nano-structured materials, produced on the base of ceramic nanopowders introduced into CC RF plasma, sustained in hydrocarbon gases. (3) development of the chemical kinetics model for the formation of solid phases in the hydrocarbon CC RF plasma: a phase consisting of the C:H coating on the nanoparticles' surface and a phase of amorphous carbon, the latter being a contaminating product. Validation of the model by experimental observations.--Résumé abrégé par UMI.
- Génie – Thèses