Twinning, Phase Transformations, and Film Formation of Zirconia-based Ceramics

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9628694 Heuer The proposed research contains three topics: i) Deformation twinning in undoped monoclinic zirconia (m-ZrO2 ) single crystals and polycrystals as a function of load, orientation and temperature will be studied using microhardness indentation. At temperatures up to 1100C, m-ZrO2 is the stable phase. The competition between indent-induced slip and twinning will be studied; ii) Heating these crystals into the tetragonal (t) phase field will allow similar studies in t-ZrO2; here, the emphasis will be on slip systems, the competition between slip and ferroelastic deformation, and the role the indentation damage plays in nucleating the martensitic t to m transformation on cooling; iii) A bio-inspired chemical route to thin film formation of pure and Y203-doped ZrO2 has been discovered. The aqueous chemistry needed to optimize film formation will be systematically studied.. Deposition of ZrO2-based films on semiconductor grade Si and Ni-base alloys have implications for oxygen sensors and thermal barrier coatings, respectively. The proposed research will examine the fundamental mechanical behavior of zirconia-based ceramics. Zirconia has been used as a model system for understanding toughening in a number of other tough ceramics. This proposal includes three research topics: deformation twinning in 1) monoclinic and 2) tetragonal zirconia studied by microhardness indentation, and 3) a study of the chemistry to optimize the deposition of self-assembling thin films of zirconia-based ceramics. Understanding these self- assembling films has the potential to enable materials researchers to deposit a film of any material on any substrate.