THE DEPENDENCE OF STRUCTURAL AND MECHANICAL-PROPERTIES ON FILM THICKNESS IN SOL-GEL ZIRCONIA FILMS

The structure, morphology, and mechanical properties of sol-gel zircon ia films have been examined using XRD, AES depth profiling, AFM, and u ltramicro indentation. There is a systematic variation in the structur e and morphology of the zirconia films with increasing thickness. Thes e changes include increases in the amount of monoclinic phase, substra te oxides, and a decrease in grain size. Ultramicro indentation measur ements indicate measured hardness increases with film thickness. The h ighest hardness value was 6.12 GPa for a 900 nm thick film. However, t hese values may be influenced by the substrate oxide layer at the film /substrate interface which increases with film thickness. The modulus of the films appears to be thickness independent. As the films are mad e up of a number of separately fired layers, it appears that the prope rty changes observed are also related to the number of thermal cycles experienced by the sample.