9803851 DeGuire In the last several years, several techniques have been described in the literature for depositing ceramic thin films from aqueous solutions at low temperatures (<100 C) on various solid substrates. Work by the PI has focused on the bioinspired use of organic self assembled monolayers (SAMs), on substrates such as single-crystal silicon and glass, as a means of inducing and controlling the formation of oxide films on the substrate. The objective of this GOALI project is to obtain a detailed understanding of the mechanism by which films form from aqueous solutions, on substrates with and without SAMs. In particular, the relative importance of heterogeneous nucleation of solid on the substrate, versus assembly of colloidal particles on the substrate, will be assessed in a variety of film-forming systems of technological interest. The project is subdivided into several areas: 1) Studies of the thermodynamics and kinetics of the formation of ceramic particles from the aqueous source solutions. The research tools to be applied include thermodynamic calculations of the degree of supersaturation of the solutions, in combination with small-angle x-ray scattering measurements of the deposition media to monitor the formation and growth of particles as a function of time; 2) Studies of the interactions between ceramic particles and the substrate surfaces, and the influences of those interactions on the films' microstructures. DLVO theory will be used to estimate the forces between ceramic particles and the substrates. The calculations will be compared to direct measurement of these forces using the atomic force microscope (AFM). The AFM will also be used to observe film growth, from its earliest stages in situ, to ex-situ observations of the films' surface topographies; 3) Experiments combining this fundamental understanding with some of the unique capabilities of SAMs to optimize growth rates and/or film microstructures for specific applicatio ns. %%% Thin film deposition from aqueous solution are potential alternatives to vapor-phase and chemical-precursor techniques. The low processing temperature minimize problems related to substrate-film interdiffusion and thermal expansion mismatch. However, the degree of control of the microstructure and thus the properties of the materials processed from aqueous solutions is not as great as from vapor-phase techniques. This project addresses that issue by the use of SAMS. The industrial collaborator in this GOALI project is Caterpillar Technical Center. The collaboration includes personnel exchange (CWRU people working at Caterpillar, the industrial scientist working at CWRU), tests being performed on equipment at Caterpillar, as well as the industrial scientist serving as a co-advisor to the graduate students. In addition to Caterpillar, the Max-Planck-Institut fur Metallforschung in Stuttgart, Germany and Oak Ridge National Laboratory in Oak Ridge, Tennessee are participating in this project. Each collaboration brings facilities and expertise that are integral to the proposed research, and offers a variety of working environments that will expand the educational value of the research experience for the student researchers involved with the project. This project is co-funded by the Ceramics Program of the Division of Materials Research and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate. ***
