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Aqueous Corrosion Data

amadeus
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Aqueous Corrosion Data

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    1. Aqueous Corrosion Data Corrosion performed with ~1cm3 samples in 100mL of DI water, 1mM NH4OH, or 1mM HCl The lowest dissolution rates occur at neutral pH with basic conditions accelerating corrosion to a greater extend than acidic conditions

    2. pH Changes of Corrosion Solutions Except for KAP see very little change for the acid and DI water solutions. The basic solution, however, shows a larger pH shift to go along with the increased dissolution rates on the previous slide.

    3. Arrhenius Fit of Dissolution Data

    4. pH stat Titration of Glass Samples

    5. Initial Reaction of Glass Species The short term pH shift of the glass samples can give a description of the number of reactive groups on the surface of each glass sample. The samples shown here are for glasses with an initial pH 9.2 KAP shows the most shift, with KMAP close.

    6. pH shift measurements of Glasses Glass is added to a solution of desired pH and the shift in pH for the first 60s is measured. This is used to calculated the moles of OH adsorbed by the glass surface. While there is some scatter as of yet, it can be seen that KAP and KMAP appear to follow the same trend. The other glass are somewhat lower than this trend initially and all of the glasses begin to come together near a pH of 7.

    7. Predominance Diagrams for KAP and KBAP

    8. Weathering of Glass Samples

    9. ERD for H depth profiles

    10. ERD of KMAP and KBAP

    11. Chain Distribution of Weathered Layer

    12. MAS-NMR of KBAP Weathering

    13. MAS-NMR of KAP Weathering

    14. 2d spectra of the KAP 7 Day sample

    15. 27Al Spectra of Corroded Glasses

    16. Thin Film XRD of Weathered Surfaces

    17. Additional Crystal Species What can be seen for the KBAP spectra is that additional species such as K2HPO4 and Al(OH)3 can be used to describe some of the peaks.

    18. Optical Microscopy Images of Fibers LG-770 fibers before and after dipping in LN2 There appears to be no noticeable difference between the two fibers

    19. AFM images of Glass Fibers

    20. Failure Strain Data for 1 week In the prior slide see that LG-770 fibers show a small number of large corrosion points ~ 50nm in height and 1mm in diameter with little to no roughness of the surface other than that. LHG-8 exhibits more surface roughness, ~5nm, but lacks the large peaks seen in LG-770.

    21. Upcoming Work Work planned for this spring and summer includes: Corrosion and Weathering of KCAP and CAP samples for comparison to the rest of the data. It may be that KMAP acts more like KAP due to some ionic radii comparisons which KCAP may give more insight to. Further NMR correlation measurements to determine which species are being preferentially attacked during the weathering process. pH stat and drift measurements in the acidic region to determine if the same trends continue. Liquid NMR measurements of short term corrosion surfaces to determine the weathering and hydrolysis rates of each glass surface. Calculation of more predominance diagrams to look for the effect of stable solution species on corrosion rates. Further weathering tests in more humidity/temperature environments for trending of corrosion. Study of Iron phosphates looking specifically on the affect of modifier composition on the corrosion stability of glasses. I am also looking at using this data to compare to some of the strength and fatigue measurements on glass fibers that Nate and Adam have performed to see if it can help explain some of their results.

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