Kristallisation und Eigenspannungsentwicklung an MOD-ZrO2-Filmen auf X4CrNil8-10-Stahlsubstraten

Abstract

The deposition of thin ceramic films by the sol-gel technique is of great technical interest especially in the fields of corrosion protection, sensor and catalytic films as well as special coatings for optical and electrical applications. This wet chemical coating technique needs less expensive hardware, which makes it easy to convert it to industrial scale. At present the limits of this technology cannot be overseen. After developing stable metal organic polymer solutions (sols) on the basis of zircon-tetra-n-propoxide, the deposition of crack free thin MOD-ZrO 2 films on stainless steel substrates was achieved (MOD: metal organic deposition). X-ray diffraction measurements were carried out in order to examine the crystallization behaviour of the sol-gel derived ZrO 2 -films. The crystallization is significantly influenced by heat treating parameters. The ZrO 2 -films crystallize first in a meta-stable cubic modification of zirconia. For heat treatment of 650°C 10 min and above a phase transformation to the stable monoclinic modification was observed. Parallel to XRD-measurements X-ray residual stress measurements were carried out. Films, which were heated with low heating rates showed much higher crystallization temperatures than fast heated films, which could be explained by the temperature dependence of nucleation rate and crystal growth.