The ability of the field ion microscope to routinely visualize individual atoms on a crystal is being used to investigate phenomena important to the atomistic understanding of overlayers. Three related topics are under study: (1) the dependence of pair interactions between adatoms upon the chemical identity of the adatoms and upon the nature of the substrate surface; (2) the contibutions of many-atom interactions to overlayer stability; and (3) the effects of interaction between adatoms upon mobility in concentrated layers.

This project involves characterization of corrosion growths in water pipes. Sample sections of pipes are removed from working drinking water systems in various cities. Water treatments are run through the systems for a period of time ranging from six months to two years, and then another sample section is removed from the system. These sections are shipped to the University of Illinois, where qualitative characterization of before-treatment and after-treatment pipes is done to determine the effectiveness of the water treatments used. Characterization techniques used include light microscopy, SEM, EDS, and XRD.

Electron microscopy is being used in conjunction with water treatment studies in an effort to better understand the role of different water treatment products in the control of lead and copper corrosion for household plumbing systems. Test coupons consisting of copper pipe partially coated with a lead-tin solder were used in several water distribution systems and in several pilot treatment studies. Now removed from service, the interior surfaces of these coupons are being characterized by SEM and EDS. One goal is to correlate the corrosion scales, mineral deposits, and other films with the different types of water treatment used and with the results of water quality analyses. Another interest is to assess the protective qualities of the mineral deposits which frequently form uniform coatings on the pipe surfaces. These layers are produced as a result of the water treatment and may be the key to solving the lead and copper corrosion problems.

While not altogether new, anodic spark deposition (ASD) is a most promising and versatile process for the application of a wide range of novel ceramic coatings that has yet to be exploited. It is a comparatively rapid, subconventional temperature process that occurs at the positive electrode of an electrolytic cell via a complex set of reactions that involves sparking. The aim of this research is to determine the feasibility of the application of diamond and/or diamondlike carbon films by ASD. Such films have also been put down in connection with this program by chemical vapor deposition techniques.

Gas tight layers of stabilized zirconia are being deposited on carbon from vapors of the chlorides by means of the local electrochemical cell set up by the electrolytic properties of the growing ceramic coating. The electrolytical properties of the coating are being evaluated as a means of protecting the carbon from oxidation at elevated temperatures in an oxidizing atmosphere. Polarization processes at the carbon electrode are being evaluated by potentiometric measurements, and the volume of oxidation reaction products is being monitored by means of a Bunsen tower.