Accession Number : ADA318628

Title :   Scanning Tunneling Microscopy Studies of the Morphology and Kinetic Pathways for Corrosion Reactions of Stressed Materials.

Descriptive Note : Final rept. 1 Jul 93-30 Jun 96,

Corporate Author : CHICAGO UNIV IL DEPT OF CHEMISTRY

Personal Author(s) : Sibener, Steven J.

PDF Url : ADA318628

Report Date : NOV 1996

Pagination or Media Count : 16

Abstract : This research program improved our understanding of how surface chemical reactions, surface stress, and atomic level microstructure influence materials oxidation/corrosion processes. Central to this effort was the construction of a new scanning probe microscopy facility which now houses a UHV-STM and a combined STM/AFM for operation in both air and electrochemical environments. It was demonstrated that applied stress fields can influence the electrochemical pitting corrosion chemistry of pure aluminum and 2024-T3 alloy. The role that surface defects play in oxidation reactions involving graphitic surfaces was also examined. Here it was shown that surface defects, including ones occurring on the atomic level, can dominate the reactivity and morphological evolution of such surfaces. Finally, high-impedance STM imaging was used to elucidate the structure and domain boundary characteristics for adsorbed self- assembling molecular films, providing information that will be needed if such films are to be used for interface passivation. The basic science opportunities addressed in this program were quite significant, and have technological implications given current interest in corrosion prevention and developing an improved fundamental understanding for stress-corrosion cracking, a topic of obvious importance to the aircraft industry.

Descriptors :   *STRESSES, *CORROSION, *MATERIALS, *MORPHOLOGY, *ELECTRON MICROSCOPY, *ALUMINUM, *KINETICS, ENVIRONMENTS, AIRCRAFT INDUSTRY, INTERFACES, TUNNELING(ELECTRONICS), CRACKING(FRACTURING), ELECTRONIC SCANNERS, REACTIVITIES, CORROSION INHIBITION, ELECTROCHEMISTRY, GRAPHITE, SURFACES, BOUNDARIES, CHEMISTRY, PURITY, DEFECTS(MATERIALS), CHEMICAL REACTIONS, EVOLUTION(GENERAL), SURFACE REACTIONS, SURFACE CHEMISTRY, STRESS CORROSION, ASSEMBLY, OXIDATION REDUCTION REACTIONS, PASSIVITY, ATOMIC ENERGY LEVELS, PITTING, MONOMOLECULAR FILMS.

Subject Categories : Laminates and Composite Materials
      Inorganic Chemistry
      Physical Chemistry
      Properties of Metals and Alloys
      Atomic and Molecular Physics and Spectroscopy
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE