| Thin Al₂O₃ films were prepared by dipping substrates into coating solutions, pulling them up, drying and then hearing processes. A sol-gel process, which comprises precipitation of aluminum monohydroxide, formation of sol and gel, was used to produce coating solutions. Effect of preparation conditions on the properties of films was examined. The viscosity of coating solutions was controlled by gelling time, and two kinds of substrates, slide glass and stainless steel were used. The contact angle between the substrate and coating solution was measured by the captive bubble method. An air bubble in the solution was not adhered to both slide glass and stainless steel. These phenomena mean the wettabilities of solution to the substrates are good. The thickness of coating films was increased with increasing the viscosity of solution, and with increasing the number of coating cycle. Defects such as, crack, opaqueness or peeling off were observed when the viscosity was higher than 10 cps. Scanning electron microscopy and wavelength dispersive X-ray analysis have been used to determine the interaction occuring at the interface. The diffusion of aluminum from the film into the substrate is confirmed by these analyses. Therefore possible bonding mechanism of Al₂O₃ films at the interface may be explained in terms of mixture of chemical reactions and diffusion of multi-component oxides. |
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