During the first phase of this NSF sponsored Small Business Innovation Research project, Giner, Inc. demonstrated increased corrosion resistance of uniformly deposited, boron-doped conductive diamond coatings on graphite substrates (fuel cell bipolar separator plate materials) and a reduction in acid absorption (in a phosphoric acid fuel cell environment) as compared to the uncoated or non-uniformly coated graphite. Very little is known regarding the relationship between growth initiation conditions on the substrate and the resulting microstructure of thin diamond coatings, and the adherence of the coatings to substrates. Hence, the research plan for Phase II focuses on: (1) effect of pretreatment process of nucleating surfaces (graphite and silicon) on nucleation density and on the nature and properties of the transition layer; (2) growth experiments for determining the variables that affect the microstructure of the diamond films; (3) determination of corrosion behavior and correlation with phase purity and crystallite size; (4) development of a process model to describe the parameters and relationships that control: (i) the formation of reproducible dense and corrosion-resistant, very thin boron-doped diamond films; and (ii) the properties of the transition layer interfaces between the films and the substrates. The diamond coating process will be done by another small business firm, Epion Corporation, under the guidance of Giner, Inc. It is expected the knowledge gained from this research will facilitate the development of advanced electrochemical cells and constitute an important contribution to diamond films technology.
