Stefan Schlichtherle

Density-related properties of metal oxide films

The density of the material in a deposited film determines many important film properties, for example hardness and abrasions resistance, adherence to the substrate, refractive index, film stress, flatness and film permeation. Chemical compound films like metal oxides, some nitrides and oxynitrides are mainly produced by reactive PVD processes. The energy input into the growing film strongly influence the density of the resulting film. High energetic coating conditions result e.g. in a high refractive index, but often also in relatively high residual optical absorption and high compressive film stress. In order to obtain films with improved properties immediately after deposition without time consuming post-deposition heat treatments, depositions of RLVIP-Ta2O5 films were carried out under relatively high oxygen pressures and under special rate conditions. The achieved reproducible film properties can practically be accepted for many low loss optical film applications.

Ceramic PVD Coatings as Dense/Thin Barrier Layers on Interconnect Components for SOFC Applications

In the last decade of SOFC metallic interconnect component development barrier coatings have proven being indispensable as functional layers and therefore gained serious attention. Diffusion processes at the interface between metallic and other cell materials have demonstrated harmful influence on degradation of SOFC stacks. Recent scientific developments of perovskite barrier layers show that innovative pulsed PVD technologies make it feasible to deposit thin films of highest density and conductivity. Simultaneously, through applying PVD methods it is possible to drastically reduce the employed perovskite material. PVD coatings in the thickness range of around 1 µm have been applied on porous substrates of Plansees P/M ODS ferritic FeCr- alloy ITM for MSC type SOFC as well as on bulk components. Long term oxidation tests at 850{degree sign}C in combination with SEM/EPMA imaging and element sensitive mappings are shown and verify the functionality of described coatings as diffusion barrier layers.