Accession Number : ADA292047

Title :   Prediction of Hydrogen Entry and Permeation in Metals and Alloys.

Descriptive Note : Annual rept. 1 Oct 93-30 Sep 94,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MATERIALS SCIENCE AND ENGINEE RING

Personal Author(s) : Pickering, Howard W.

PDF Url : ADA292047

Report Date : FEB 1995

Pagination or Media Count : 45

Abstract : This report summarizes results of the past year on our continuing experiments directed to the problem of hydrogen entry and degradation of materials both of planar surfaces and for the more complicated recessed surface. For the planar surface the hydrogen permeation and scanning tunneling microscopy (STM) techniques were used, and for the recessed surface the study used the hydrogen permeation technique and a microscopy/electrochemical probe technique. Microstructural effects and the role of microbes are also under study. In aqueous solutions both IR drop and acidification within recesses in iron surfaces were found to enhance proton reduction and hydrogen absorption. In addition, it was found that flat, smooth surfaces can form or develop recesses as a result of corrosion or other reasons, e.g., grain boundary grooves that form during corrosion of Cr-depleted alloy in sensitized stainless steel. These recesses were found to be just as prone to proton discharge and hydrogen absorption as pre-existing recesses. Distributions of anodic and cathodic reaction sites were analyzed within a propagating crack under cathodic protection conditions using an IR based model. Results are presented of STM studies of hydrogen adsorption from the gas phase on silicon. jg

Descriptors :   *METALS, *PERMEABILITY, *ALLOYS, *HYDROGEN, SCANNING, PROPAGATION, PROBES, MICROSTRUCTURE, CORROSION, DEGRADATION, MODELS, SOLUTIONS(MIXTURES), WATER, ADSORPTION, MATERIALS, TUNNELING(ELECTRONICS), CRACKS, ELECTRONIC SCANNERS, STAINLESS STEEL, ELECTROCHEMISTRY, VAPOR PHASES, PROTONS, MICROSCOPY, REDUCTION, ELECTRON MICROSCOPY, IRON, SURFACES, SILICON, PLANAR STRUCTURES, ABSORPTION, CATHODIC PROTECTION, INFRARED SPECTRA, MICROORGANISMS, ACIDS, SENSITIZING.

Subject Categories : Physical Chemistry
      Inorganic Chemistry
      Properties of Metals and Alloys
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE