Accession Number : ADA307403

Title :   Adhesion and Transfer of Polytetrafluoroethylene to Tungsten Studied by Field Ion Microscopy.

Descriptive Note : Technical note,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Brainard, William A. ; Buckley, Donald H.

PDF Url : ADA307403

Report Date : AUG 1972

Pagination or Media Count : 21

Abstract : Mechanical contacts between polytetrafluoroethylene (PT FE) and tungsten field ion tips were made in situ in the field ion microscope. Both load and force of adhesion were measured for varying contact times and for clean and contaminated tungsten tips. Strong adhesion between the PTFE and clean tungsten was observed at contact times greater than 2-1/2 min (forces of adhesion were greater than three times the load). For times less than 2-1/2 min, the force of adhesion was immeasurably small. The increase in adhesion with contact time after 2-1/2 min can be attributed to the increase in true contact area by creep of PTFE. No adhesion was measurable at long contact times with contaminated tungsten tips. Neon field ion micrographs taken after the contacts show many linear and branched arrays which appear to represent PTFE that remains adhered to the surface even at the high electric fields required for imaging.

Descriptors :   *ADHESION, *TUNGSTEN, *FIELD ION MICROSCOPY, MECHANICAL PROPERTIES, LOADS(FORCES), ELECTRIC FIELDS, IMAGES, CREEP, TRANSFER, LINEAR ARRAYS, CONTAMINATION, ELECTRIC CONTACTS.

Subject Categories : Polymer Chemistry
      Inorganic Chemistry
      Adhesives, Seals and Binders
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE