Adsorption of hydration inhibitors

in part, on the results of the previous section, we decided to investigate the use of several organic hydration inhibitors on PAA and Forest Products Laboratory (FPL)(92) sodium dichromate-sulfuric acid etched surfaces.(3.5,i3,9i,93) One of the inhibitors that is very successful is nitrilotris methylene phosphonic acid NTMP, N[CH2P(0)(OH)2]3. It provides hydration resistance for FPL surfaces in a manner similar to anodization in phosphoric acid, i.e., it forms a protective molecular layer that does not allow the aluminum oxide substrate to hydrate until the inhibitor complex dissolves. 

FIGURE 21. AI2O3-NTMP-H2O SBD showing (a) the surface composition of FPL surfaces after 30 min immersion in aqueous solutions of NTMP at concentrations ranging from 0.1 to 500 ppm, with increases going from left to right, and (b) the hypothetical path representing no displacement of water. (From Reference 3.) 

In this chapter, we have attempted to provide an introduction to the capabilities, limitations, and potential pitfalls in the data analysis of XPS and AES/SAM, the surface analytical techniques that we have found the most useful in the study of adhesive bonding and that have the most widespread availability and applicability. Other groups have used some of the other techniques mentioned in the introduction to provide important information in their studies for more information on these techniques, the reader is encouraged to consult the next chapter or some of the many reviews and applications.(7-23,94-100) 

We then discussed several examples of how these surface-sensitive techniques can be used to solve problems in adhesion science. The studies chosen were designed to illustrate the methodology involved, the interplay among different techniques, and the usefulness of different forms of data analysis. 

I would like to thank G. O. Cote, H. M. Clearfield, and K. A. Olver for use of some of their unpublished results and C. Allen for an editorial reading of the manuscript. This chapter was supported in part by the National Science Foundation under grant DMR-8401401. Work on the Ti adherends was funded by the Office of Naval Research under contract N00014-85-C-0804. 

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Surface-sensitive techniques for use in the study of adhesive bonding are discussed, including X-ray photoelectron spectroscopy and auger electron spectroscopy/scanning auger microscopy. Data analysis is considered, with reference to quantification, chemical-state information, depth-distribution information and surface-behaviour diagrams. Applications to adhesive bonding are described, particularly failure analysis, hydration of phosphoric acid-anodised aluminium and adsorption of hydration inhibitors. 100 refs. 

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