Accession Number : ADA307856

Title :   Bondability of Ti Adherends 2. Humid Environment Effects.

Descriptive Note : Final rept. 15 Aug 80-15 Sep 81,

Corporate Author : MARTIN MARIETTA CORP BALTIMORE MD

Personal Author(s) : Natan, Menachem ; Breen, Kathleen R. ; Venables, John D.

PDF Url : ADA307856

Report Date : 22 SEP 1981

Pagination or Media Count : 61

Abstract : We have demonstrated the importance of oxide morphology to the properties of bondments of Al and Ti structures in previous studies. Microrough, porous oxides which provide good mechanical interlocking with the primer/adhesive system were found essential to good bondability. Ability to withstand long-term degradation in humid environments in Al was found to be poor, because the Al oxide was transformed into hydroxide in a relatively short time. On the other hand, Ti oxides are known to be very stable. The purpose of this study was to investigate possible humidity-induced morphological and structural changes on these latter oxides and to relate them to known failure data. We found that both changes occur at temperatures/times relevant to service conditions. Typically, the original oxides are amorphous TiO2. They crystallize into anatase through a dissolution-precipitation process, which is strongly dependent on temperature, oxide porosity and surface contamination. This transformation may be important in the degradation of adhesive bonds to Ti.

Descriptors :   *OXIDES, *ALUMINUM, *ADHESIVE BONDING, *HIGH HUMIDITY, *TITANIUM OXIDES, TEMPERATURE, MECHANICAL PROPERTIES, ENVIRONMENTS, DEGRADATION, MORPHOLOGY, FAILURE, POROSITY, PRIMERS, SURFACES, BONDED JOINTS, CONTAMINATION, ADHESIVES, HYDROXIDES, POROUS MATERIALS.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Adhesives, Seals and Binders
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE