Relation between structure and mechanical properties (elastoplastic and fracture behavior) of hybrid organic-inorganic coating

The mechanical properties of various inorganic organic films were studied and compared in order to investigate the relation between structural modifications and the mechanical behavior. Films were prepared by a sol-gel process and spin-coated on silicon substrate. The organic-inorganic hybrid is composed of a mixture of colloidal silica and organosiloxane precursors. The functionality of the organosiloxane and the nature of its organic part have been modified to obtain a structural change. Mechanical properties were studied using nanoindentation. Analysis of the strength evolution as a function of depth of indentation shows the layer hardness and elastic modulus. Moreover, coating and interface toughness and residual stresses were determined by a time resolved study of energy dissipation during indentation. The structural changes were determined using liquid and solid Si-29 NMR spectroscopy. Quantity of partially and fully condensed species in the deposited sol and final solid are discussed in relation to the mechanical properties.