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Cutting and Sputtering: Getting to the Buried Interface

Cutting and Sputtering: Getting to the Buried Interface. John F Watts The Surface Analysis Laboratory Department of Mechanical Engineering Sciences 2 July 2014. The Problem!. Inorganic Layers. J E Castle et al, Corr Sci , 16 , 145-158, (1975). High Temperature Oxidation.

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Cutting and Sputtering: Getting to the Buried Interface

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  1. Cutting and Sputtering: Getting to the Buried Interface John F Watts The Surface Analysis Laboratory Department of Mechanical Engineering Sciences 2 July 2014

  2. The Problem!

  3. Inorganic Layers J E Castle et al, Corr Sci, 16, 145-158, (1975)

  4. High Temperature Oxidation J C Rivière et al, Surf Sci, 117, 629, (1982) R K Wild, Spectrochim Acta, 40B, 827, (1985)

  5. 10’s m - mm Interface Region Substrate Adhesive or Coating 100’s m - mm d  ARXPS d ~10nm  X-ray spectroscopies d ~200nm  RBS d ~1μm Buried Interfaces: The Problem One solution is mechanical sectioning of the sample followed by analysis of the exposed interfacial region

  6. The Buried Interface Obtaining analytical information from intact interfaces is very difficult. Carrying out in-situ experiments within the spectrometer can be useful but only rarely is the interphase chemistry exposed in this manner J F Watts, Surf Interf Anal, 12, 497-503, (1988)

  7. Oxide Stripping Chemical removal of metal substrate, depth profiling of oxide in situ by ion sputtering. Interphase can then be analysed directly J F Watts, J E Castle, J Mat Sci,18, 2987, (1983)

  8. XPS Spectrum at Interphase Fe(II) Fe(II) satellite Iron 2p3/2 spectrum showing Fe(II) component at interface. Oxide is entirely Fe(III).

  9. Model of Interphase

  10. Complementary Dissolution

  11. Energy Filtered TEM (a)(b) Energy-filtered (PEELS) TEM images of adhesively bonded aluminium showing the interpenetration of organic and oxide phase that is achieved when a primer is used (a). In the absence of a primer (b) the adhesive merely forms a interfacial boundary with the oxide. A J Kinloch, M Little, J F Watts, Acta Materialia, 48, 4543, (2000)

  12. MICROM 355S

  13. sample Ultra-Low Angle Microtomy microtome blade angled sectioning block polyethylene Angle Sectioning Block 12 x 12 x 7 mm3 + 25 mm = 0.03O + 50 mm = 0.07O + 100 mm = 0.15O + 200 mm = 0.33O

  14. Small area XPS analysis mode (100 mm) Coating q Substrate ULAM Depth Profiling S J Hinder, C Lowe, J T Maxted, J F Watts, J Mater Sci, 40, 285, (2005)

  15. ULAM/Small Area XPS Depth Profile PVdF (topcoat) Polyurethane (primer) S J Hinder, J F Watts, Surf Interf Anal, 36, 1032-1036, (2004).

  16. a) b) d) c) 2 3 1 250 nm 500 mm ToF-SIMS of ULAM Interface +ve SIMS -ve SIMS Polyurethane ions • m/z = 149: C8H5O3+ • m./z = 26: CN- • m/z = 59: C3H4F+ • m/z = 19: F- PVdF ions S J Hinder, C Lowe, J T Maxted, J F Watts, Surf Interf Anal, 36, 1575, (2005)

  17. a) 25 66 41-42 49 121 100 c) 2 3 1 19 c) 39 49 85 Negative SIMS Spectra from Images Point 2: Bulk Polyurethane Point 1: Bulk PVdF

  18. b) 19 c) 2 85 31 3 71 55 1 87 121 141 185 Reconstructed ToF-SIMS of Interphase Point 3: PU and PVdF at Interface

  19. 31 71 41 85 55 185  A negative ion ToF-SIMS mass spectra of the pure acrylic co-resin component of the PVdF topcoat formulation in the mass range 30-200u x10 ToF-SIMS of Acrylic Copolymer Component of PVdF Topcoat

  20. a) b) Retrospective Images of Acrylic Ions • Negative Ion Mass • Selected Images • m/z = 31: CH3O- • m/z = 55: C3H3O- • m/z = 71: C3H3O2- • m/z = 85: C4H5O2- • m/z = 87: C4H7O2- • m/z = 141: C9H13O4- c) d) e) f)

  21. Adhesive Aluminium foil Adhesive Interface Adhesive/Aluminium/Adhesive Adhesive Line scan used Model Specimen for ULAM M-L Abel, unpublished data (2008)

  22. Polyamide Powder Coating + Aminosilane addition 100 mm thick thermoplastic polyamide powder coating with aminosilane added to the powder stock prior to spray coating ULAM is carried out on the intact outer surface to provide profile of air/coating interface and delaminated coating interfacial failure surface to provide steel/coating profile M Guichenuy, J F Watts, M-L Abel, M Audenaert, Surf Interf Anal, 38, 168-171, (2006).

  23. Atomic % // Depth / μm Air/Coating Interface Coating/Steel Interface 4 3 2 1 0 Aminosilane in PA11 Coating 100 mm thick polyamide powder coating with aminosilane added to the powder stock prior to spray coating

  24. 10’s m - mm Interface Region Substrate Adhesive or Coating 100’s m - mm d Thin Film Solution Deposit a very thin layer of organic phase This may be from the plateau region of an adsorption isotherm Prepare specimen at monolayer coverage (i.e. plateau region) for XPS or ToF-SIMS analysis It is then possible to probe interface chemistry directly

  25. Organosilane Adhesion Promoters • Molecular Dynamics Models of: • Epoxy • Amino • Vinyl

  26. ToF-SIMS to Identify Specific Interactions The intense SiOAl+ peak is indicative of a covalent bond between the aluminium oxide and the organosilane adhesion promoter

  27. Conclusions • A variety of “mechanical” and chemical methods to approach interfaces • ULAM provides an easy way to section samples at very low angles which has the potential to provide chemical depth profiles at very high depth resolution when used in conjunction with a surface analysis method such as XPS or ToF- SIMS • Polymer/polymer systems are straightforward, if the candidate substrate is metal a thin foil must be used • Thermosetting systems can be cut at ambient temperature, thermoplastic systems may need a cold stage

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