Paper PS+SE-WeM11
Laser-Assisted Plasma Coating at Atmospheric Pressure: Production of Yttria-Stabilized Zirconia Thermal Barriers

Wednesday, November 2, 2011, 11:20 am, Room 201

A laser-assisted plasma-coating technique at atmospheric pressure (LAPCAP) for use in thermal-barrier coatings (TBC) deposition has been developed. This technique allows PVD-quality depositions to be done at atmospheric pressure. The microwave source employed has a working frequency at 2.45 GHz, and a maximum input power of 6 kW, and the attached plasma torch head has the ability to generate various types of atmospheric-pressure plasmas at the temperatures of room temperature (20°C) to more than 2,000 °C. Optical emission spectroscopy (OES) technique has been used to spatially analyze some critical characteristics of plasma, such as electron density (n_e > 10¹⁴cm^-3), electron temperature (T_e ~ 1 eV), and plasma gas temperature (T_g ~ 400-3,000 K), under different operating conditions (gas type, input power and gas flow rate). A helium atmospheric plasma has been used to assist in Nd:YAG laser ablation (f = 100 Hz, Energy/pulse = 20 mJ at 266 nm; 120 mJ at 532 nm; 325 mJ at 1064 nm) of a 3% yttria-stabilized zirconia (3YSZ) target, to provide a means to deposit high quality, adhesive thin films on René N5 superalloy substrates with better lamination at a relatively higher deposition rate (~1,000 nm/min), in comparison to traditional PVD methods. The morphology and characteristics of the films have been compared at three laser wavelengths (266 nm, 532 nm and 1064 nm), different laser energy densities (1-10 J/cm²) and substrate temperatures (20-1100 ºC), using microanalysis techniques such as scanning electron microscope (SEM), focused ion beam (FIB), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).