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Accession Number:
ADA114617
Title:
Bondability of Ti Adherends
Descriptive Note:
Final rept. 1 Apr 1979-31 Mar 1980
Corporate Author:
MARTIN MARIETTA LABS BALTIMORE MD
Report Date:
1980-04-30
Pagination or Media Count:
52.0
Abstract:
Surface oxides on titanium prepared for adhesive bonding by eight different pretreatment processes were examined using STEM and AugerESCA techniques. The results indicate that the surfaces can be divided into three groups according to similarities in their oxide morphologies Group I exhibits little surface roughness Group II is characterized by macro-roughness features greater than 1.0 micrometers and Group III exhibits extensive porosity and microroughness, similar to features found on aluminum prepared by the phosphoric acid anodize process. Wedge tests performed at NADC, but discussed here indicate that Group III adherends chromic acid anodize and alkaline peroxide treatments produce far more durable bonds than those in Groups I or II. Hence, a direct correlation exists between oxide morphology and bond durability for Ti adherends. We found similar evidence for the importance of oxide morphology to the properties of bondments in our prior work on Al but with one important difference. Because Al oxides are relatively unstable in a moist environment, the bond can suffer long-term degradation. In contrast, the Ti oxides are extremely stable against the effects of moisture. We conclude, therefore, that the combination of oxide stability and micro-roughness that can be developed on Ti by the CAA or alkaline peroxide processes portends a very bright future for adhesively bonded Ti structures.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
