HIGH SPEED FORMATION OF FINE CERAMIC LAYERS BY NANOPARTICLES FILLER ROD THERMAL SPRAYING

Thermal nanoparticles spraying were newly developed as novel technologies to mate fine ceramics layers with higher deposition rates. Nanometer sized alumina particles of 200 am in average diameter were dispersed into liquid resins at 40 % in volume fraction. The obtained slurries were solidified through heat polymerization to crate composite rods of phi 4x100 mm in dimensions. The solid rods were introduced into the acetylene and oxygen gas flame for the coaxial direction at a feeding speed of 5.0 mm/s by using a mechanical actuator. On the stainless steels substrates, the fine alumina layers of 500 mu m in thickness were formed at a speed of 100 mu m/s. Microstructures and compositional distributions in the coated layers were observed and analyzed by using a scanning electron microscopy and energy dispersive X-ray spectroscopy. Effective dielectric constants of the alumina layers were measured by using terahertz wave time domain spectroscopy to estimate the volume fraction of nanometer sized pores.