PacSurf2024 Session TF1-MoE: Thin Films - Materials I

Plasma has been actively used in semiconductor and nanomaterial manufacturing. As the structures of nanostructures and semiconductor devices become more complex, plasma process technology based on plasma characteristic measurement is needed. In this invited talk, several key plasma process results, including analysis of the correlations between process results and plasma variables, are presented.

Reducing polluting gases emissions is a major strategic challenge for the aeronautic industry. Two approaches exist to achieve this : increasing engine operating temperatures and/or reducing the total mass of the aircraft. Titanium alloys, due to their low density, good damage tolerance, and excellent fatigue resistance, are particularly attractive for use up to temperatures of 500°C.

To date, the scientific challenge concerning these alloys is to extend their operating temperature resistance up to 600-700°C while maintaining or improving their specific properties required for the aimed application. One of the main causes of degradation in these alloys when used at high temperatures is related to oxidation. Actually, for these materials, oxidation can occur in two distinct ways : firstly, the formation of an external oxide layer (TiO₂), and secondly, significant oxygen diffusion within the underlying alloy. This second phenomenon is linked to the high solubility of oxygen in titanium. In both cases, without additional protection, the use of titanium alloys at high temperatures considerably reduces their mechanical properties, especially ductility.

In this context, the main goal of this study is focused on the design, synthesis and characterization of a high temperatures anti-oxidizing coating based on rare earth aluminate for enhanced titanium alloys used in aeronautics. In this work, we are interested in the synthesis of protective coatings by using the sol gel process, which is a versatile method allowing direct enduction of the sol on metallic substrates. Thus, leveraging precise control over sol chemistry enables the reach of coatings with desired stoichiometry. The morphology of the coatings is meticulously examined via SEM. Additional characterizations utilizing XPS, solid NMR, and thermal analyses where used to understand curing mechanisms. Initial oxidation tests reveal promising prospects for the application of these coatings in aeronautic contexts, potentially enhancing engine efficiency while mitigating environmental impact.

Aluminum-doped cadmium oxide (CdO:Al) thin films are deposited on silica substrates by the sol–gel spin-coating method as a function of spin coater’s rpm (revolution per minute). Cadmium acetate dihydrate and Aluminum nitrate have been taken as the precursor material and a source of Al-dopant respectively. CdO:Al thin films are characterized by x-ray diffraction (XRD), Fourier Transform Infrared (FT/IR), Field emission scanning electron microscopy (FE-SEM) and SEM-EDX. XRD result indicates the highest crystallinity at 6000 rpm with a crystallite size of 31.845 nm, cubic phase formation, and strain of ~1.6 X10^-2. FE-SEM/SEM/EDX shows the well-faceted homogeneous surface structure at 6000 rpm having an average particle size of 130.05 nm. FT/IR confirms the presence of CdO:Al in the film with the peak position shifting to higher wavenumbers.