Mechanical behaviour of crack coating film Al2O3

Mechanical behaviour of crack coating film Al2O3. The multicraking test consists in studying the cracks network appearing in a film A four point bending test has been chosen. The number and the position of cracks network versus the strain are recorded by optical microscopy. A statistical treatment taking into account the random character of the determination of two fundamental: rupture probability density (DPR) related to the brittleness and relaxed zone size (TZR) linked to the quality of the interface between the film and the substrate which can give indications on the adhesion. The experimental part is devoted to the study of alumina (Al2O3) films deposited by RMPECVD (Remote Microwave Plasma Enhanced Chemical Vapor Deposition) on stainless steel (316L). Correlations have been established between the deposition parameters, surface preparation and mechanical properties. The modelling of this test using the Abaqus (R) code allows to visualise the stress distribution and to show the effect of the presence of cracks.