Research on the thermal expansion behavior of anodic films on aluminium

Technical methods for the measurement of thermal expansion coefficient of t hin films are briefly outlined. Two methods and their principles for the me asurements of thermal expansion coefficients of anodic films, which an base d on the X-ray diffraction, are introduced. Owing to the anodic films being composed of amorphous Al2O3 and part crystalline Al2O3, one method was to use powders of anodic film. The thermal expansion coefficient can be deduce d by the linear relationship between the lattice spacing of the correspondi ng diffracted planes of Al2O3 and temperature. The other method is that the rmal strains in the film were measured by in situ X-ray diffraction with th e complete sample, i.e. the film and substrate attached together. In additi on, the difference of values obtained by the above methods was analysed. (C ) 1999 Elsevier Science S.A. All rights reserved.