Mechanical Properties of Electrostatically Self-Assembled Al2O3–ZrO2 Nanocomposites Prepared at Room Temperature

Alternate layers of Al₂O₃ and ZrO₂ nanocomposite films were prepared on silicon wafers and glass substrates at room temperature using the electrostatic self-assembly monolayer (ESAM) process. The versatile approach of the ESAM process provides the possibility of integrating diverse inorganic colloids on the nanosize level in a layer-by-layer or block-by-block fashion. Further, it allows the combination of inorganic colloids and organic molecules, making it possible to fabricate thick films with large pores and good stress relaxation. Highly ordered, micron-thick films have been formed, sintered, and characterized by scanning electron microscopy and ellipsometry. There is no significant visible crack formation for Al₂O₃–ZrO₂ composite films after heat treatment at 1200°C for 2 h, although significant thickness reduction occurs. The hardness and Young's modulus of these films before and after sintering were measured using nanoindentation techniques.