Abstract
CO2 laser deposition apparatus was newly developed, which enabled the high power laser- and the long time deposition without breaking window. Alumina thin films were deposited on stainless steel using a continuous CO2 laser (λ=10.6μm) for ablation of the alumina target.
In this paper, the effect of various deposition parameters on hardness, deposition rate and adhesive strength of alumina films were investigated. Alumina films were analyzed using a scanning electron microscope (SEM), a X-ray diffractometer, an Auger electron spectroscope (AES) and a X-ray photoelectron spectron spectroscope (XPS). The results are summarized as follows.
(1) Crack free films were formed at the substrate temperature of more than 673 K, although many cracks were observed in the films formed at room temperature.
(2) Hard films more than Hk 1000 were formed under the pressure of less than about 1.33 Pa.
(3) Depositon rate was controlled in the range of 10-3-8×10-2μm/s by varying the laser power, the ambient pressure and the distance between target and substrate. Deposition rate of this deposition method was much higher than that of Ion plating.
(4) Film hardness had an excellent correlation with the deposition rate. Hard films more than Hk 2000 were formed with deposition rate of less than 3.3×10-3 μm/s.
(5) Adhesive strength of hard films more than Hk 1000 by tensile test were higher than 40 MPa.
(6) The deposition by a CO2 laser deposition resulted in stoichiometry close to the target.
(7) Crystal structures of these films were found to be amorphous.
