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Iezzi webinar

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Overview of forensic engineers' analytical techniques for attorney use.

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Iezzi webinar

  1. 1. HELPFUL INFORMATION FOR ATTORNEYS WHEN WORKING WITH FORENSIC ENGINEERS© Dr. Robert Iezzi Docs > Iezzi Webinar.pptx
  2. 2. 2 OUTLINE  What Do Forensic Engineers Do ?  Types of Analytical Tools Commonly Used  Case Studies  Summary
  3. 3. 3 WHAT DO FORENSIC ENGINEERS DO ?
  4. 4. 4 WHAT DOES A FORENSIC ENGINEER DO ?  Determines reasons why products fail  What went wrong  Why it went wrong  How it went wrong Unbiased, accurate, defendable results
  5. 5. 5 ANALYTICAL TOOLS
  6. 6. 6 INITIAL SAMPLE OBSERVATION
  7. 7. 7 ANALYTICAL TOOLS  Optical Microscopy  Scanning Electron Microscopy  Energy Dispersive X-ray Spectroscopy (EDS)  Metallographic Cross-sections  Confocal Scanning Optical Microscopy  Atomic Force Microscopy (AFM)  X-ray Photoelectron Microscopy (XPS)
  8. 8. 8 ANALYTICAL TOOLS  Transmission Electron Microscopy (TEM)  Auger Electron Spectroscopy  Fourier Transform Infrared Spectroscopy (FTIR)  Gas Chromatography Mass Spectrometry (GC-MS)  X-ray diffraction (XRD)  X-ray Radiography
  9. 9. 9 OPTICAL MICROSCOPY
  10. 10. 10 OPTICAL MICROSCOPY  Optical microscope  Often referred to as light microscope  “As-is” samples - need sample to fit under lens  No surface prep  2-dimensional images  Direct link to camera and TV monitor  Light filters to see different features – polarized light shows crystals in polymers  ~2X to 2,000X magnifications  Resolution ~0.5 micron
  11. 11. 11 OPTICAL MICROSCOPY
  12. 12. 12 OPTICAL MICROSCOPY How Do I Use Take “as-is” photos of every sample I analyze Document original condition Use polarized light to observe structure of plastics
  13. 13. 13 SCANNING ELECTRON MICROSCOPY (SEM)
  14. 14. 14 SCANNING ELECTRON MICROSCOPY (SEM)  Produces images of a sample by scanning it with a focused beam of electrons  Electrons interact with atoms in the sample, producing various signals that contain information about the sample's surface features  Resolution better than 1 nanometer - 1 billionth of a meter  Detects the outer few microns of surface
  15. 15. 15 SCANNING ELECTRON MICROSCOPY (SEM)  More than 500,000 magnification, about 250 times the magnification limit of the best optical microscope  Samples must fit in the specimen chamber (~6” max)  Samples must be in high vacuum and must be electrically conductive  Non-conductive samples must be coated with ultra-thin conductive coating to prevent surface charging
  16. 16. 16 SCANNING ELECTRON MICROSCOPE
  17. 17. 17 SCANNING ELECTRON MICROSCOPY (SEM) Smooth metal facets characteristic of brittle fracture
  18. 18. 18 SCANNING ELECTRON MICROSCOPE How Do I Use Frequently Very high resolution/quality, high magnification images of “as-is” samples Minimal surface prep – original sample condition preserved Cost effective Very high “Bang for the Buck”
  19. 19. 19 ENERGY DISPERSIVE X-RAY SPECTROSCOPY (EDS)
  20. 20. 20 ENERGY DISPERSIVE X-RAY SPECTROSCOPY (EDS)  EDS is an analytical capability that can be coupled with SEM to determine elemental composition  The impact of the electron beam on the sample produces x-rays that are characteristic of the elements present on the sample
  21. 21. 21 ENERGY DISPERSIVE X-RAY SPECTROSCOPY (EDS)
  22. 22. 22 ENERGY DISPERSIVE X-RAY SPECTROSCOPY (EDS) How Do I Use Frequently Get elemental analysis results quickly on specific locations noted on SEM micrograph Cost included in SEM cost
  23. 23. 23 METALLOGRAPHIC CROSS– SECTIONS
  24. 24. 24 METALLOGRAPHIC CROSS– SECTIONS  Cut a “cross-section” of sample to obtain edge view – analogous to cutting into a steak on the grill to see if its cooked to your liking  “Mount” the cross-section in a plastic material
  25. 25. 25 METALLOGRAPHIC CROSS– SECTIONS  Sample then grinded and polished using successively finer abrasive particles to produce a scratch-free mirror finish  Analyze the cross-section in SEM or other methods discussed
  26. 26. 26 METALLOGRAPHIC CROSS– SECTIONS
  27. 27. 27 METALLOGRAPHIC CROSS– SECTIONS How Do I Use Frequently Particularly to determine why coatings fail or corrosion mechanisms Used with SEM or other tests methods
  28. 28. 28 CASE STUDIES USING THESE ANALYTICAL TECHNIQUES
  29. 29. 29 CASE #1 CORROSION OF PAINTED ALUMINUM WINDOW & DOOR FRAMES
  30. 30. 30 CORROSION OF PAINTED ALUMINUM WINDOW FRAMES
  31. 31. 31 CORROSION OF PAINTED ALUMINUM FRAMES
  32. 32. 32 CORROSION OF PAINTED ALUMINUM FRAMES
  33. 33. 33 CORROSION OF PAINTED ALUMINUM FRAMES
  34. 34. 34 CORROSION OF PAINTED ALUMINUM FRAMES
  35. 35. 35 CORROSION OF PAINTED ALUMINUM FRAMES
  36. 36. 36 CORROSION OF PAINTED ALUMINUM FRAMES Conclusions  Premature corrosion  Not due to aluminum substrate, window manufacturer, or paint company  Was due to poor pretreatment process by company who painted the product  Paint lifted from the pretreatment layer  Poor pretreatment layer likely due to  Use of tap process water, not de-ionized water  Contaminated water  Poor process control
  37. 37. 37 CASE #2 CORROSION OF COPPER ROOFING COATED WITH LEAD
  38. 38. 38 LEAD-COATED COPPER
  39. 39. 39 LEAD-COATED COPPER
  40. 40. 40 LEAD-COATED COPPER
  41. 41. 41 LEAD-COATED COPPER
  42. 42. 42 LEAD-COATED COPPER Conclusion  Premature corrosion caused by porosity and non-uniformity of the lead coating  The porosity exposed the copper substrate, creating an electrochemical corrosion cell which accelerated the corrosion of the lead  Poor LCC manufacturing
  43. 43. 43 CASE #3 MANGANESE PHOSPHATE COATING
  44. 44. 44 MANGANESE PHOSPHATE
  45. 45. 45 MANGANESE PHOSPHATE
  46. 46. 46 MANGANESE PHOSPHATE Conclusions  The premature failure of the compressors was due to the alternate MnP coating, which: -was very rough, non-uniform, and porous -wore away the compressor seals at an accelerated rate, causing the compressor to lose pressure and not pump refrigerant
  47. 47. 47 CONFOCAL SCANNING OPTICAL MICROSCOPY
  48. 48. 48 CONFOCAL SCANNING OPTICAL MICROSCOPY  Recent development in last 20 years  Evaluate “as is” sample - no sample prep or vacuum chamber  Filters out out-of-focus blur from 3- dimensional samples  Permits imaging of 3-dimensional samples or very rough surfaces  Gives quantitative measurements of height, surface profiles, and 3- dimensional image reconstruction
  49. 49. 49 CONFOCAL SCANNING OPTICAL MICROSCOPY Partial profile of 1-Euro coin
  50. 50. 50 CONFOCAL SCANNING OPTICAL MICROSCOPY How Do I Use Rarely – only when I need extreme detail about the surface features of surface sample Very few test labs have this equipment - relatively new and expensive Long time to process the sample = high cost per sample
  51. 51. 51 ATOMIC FORCE MICROSCOPY (AFM)
  52. 52. 52 ATOMIC FORCE MICROSCOPY (AFM)  AFM Analysis provides visual images with atomic resolution of surface features  Capable of quantifying surface roughness of samples down to the nanometer scale
  53. 53. 53 ATOMIC FORCE MICROSCOPY (AFM)
  54. 54. 54 ATOMIC FORCE MICROSCOPY (AFM) How Do I Use When I need extreme detail about the surface features of a flat sample Use confocal scanning optical microscopy if surface is not flat
  55. 55. 55 X-RAY PHOTOELECTRON MICROSCOPY (XPS)
  56. 56. 56 X-RAY PHOTOELECTRON MICROSCOPY (XPS)
  57. 57. 57 X-RAY PHOTOELECTRON MICROSCOPY (XPS) How Do I Use When I need to know the chemical compounds present on the surface (top 0 - 10 nm) of a material – not just chemical elements
  58. 58. 58 TRANSMISSION ELECTRON MICROSCOPY (TEM)
  59. 59. 59 TRANSMISSION ELECTRON MICROSCOPY (TEM)  Provides an image of a sample by transmitting beam of electrons through an ultra-thin sample  Image resolutions about 0.1 nm are produced  TEM has better spatial resolution/images than SEM or optical microscopy, but requires much more sample preparation
  60. 60. 60 TEM
  61. 61. 61 TRANSMISSION ELECTRON MICROSCOPY (TEM)  Provides extremely fine detail - even as small as a single column of atoms, which is thousands of times smaller than the smallest resolvable object in a light microscope
  62. 62. 62 TRANSMISSION ELECTRON MICROSCOPY (TEM) How Do I Use Rarely use because I usually do not need details down to the atom size TEM more suitable for basic material research at atomic level Sample prep tedious – very thin samples needed to transmit electrons through it Very few labs have TEM High cost per sample Overkill for most of my work
  63. 63. 63 AUGER ELECTRON SPECTROSCOPY
  64. 64. 64 AUGER ELECTRON SPECTROSCOPY
  65. 65. 65 AUGER ELECTRON SPECTROSCOPY How Do I Use Use when I need visualization of spatial distribution of chemical elements on the top few atom layers of sample surface Ideal for metals but polymers may degrade during analysis Very few labs have this equipment High cost per sample
  66. 66. 66 FOURIER TRANSFORM INFRARED SPECTROSCOPY (FTIR)
  67. 67. 67 FOURIER TRANSFORM INFRARED SPECTROSCOPY (FTIR)  Chemical analysis  Identifies organic materials - plastics, lubricants, adhesives and cleaning agents  Ideal for the direct, in situ, analysis of organic contaminants on metallic surfaces
  68. 68. 68 FOURIER TRANSFORM INFRARED SPECTROSCOPY (FTIR)
  69. 69. 69 FOURIER TRANSFORM INFRARED SPECTROSCOPY (FTIR) How Do I Use Frequently for chemical analysis of organic material (paints, plastics, etc.) Fast, inexpensive test Most chemical test labs have FTIR
  70. 70. 70 GAS CHROMATOGRAPHY MASS SPECTROMETRY (GC-MS)
  71. 71. 71 GAS CHROMATOGRAPHY MASS SPECTROMETRY (GC-MS)  Quantifies organic volatile and semi- volatile compounds  Gas chromatography (GC) separates mixtures into individual components  Mass spectrometry (MS) - identifies the various components  Each compound has a unique mass spectrum that can be compared with mass spectral databases  Through use of standards, quantitation is also possible  GC-MS analysis can work on liquids, gases and solids
  72. 72. 72 GAS CHROMATOGRAPHY MASS SPECTROMETRY (GC-MS) How Do I Use Frequently for chemical identification of volatile compounds of solids, liquids, and gases Examples – outgassing of plastic food containers or can coatings, composition of vapors, chemical fumes, etc. Fast, inexpensive test Most chemical test labs have GC-MS
  73. 73. 73 X-RAY DIFFRACTION (XRD)
  74. 74. 74 X-RAY DIFFRACTION (XRD)  Characterizes crystalline materials  Enables quick phase identification for a large variety of crystalline samples  Provides information on structures, phases, preferred crystal orientations, average grain size, crystallinity, crystal defects, etc.
  75. 75. 75 X-RAY DIFFRACTION (XRD) How Do I Use To identify the composition & crystalline forms of metals Degree of Crystallinity of plastics and paint coatings Short time to process sample Low cost per sample Only useful for crystalline materials, not amorphous materials
  76. 76. 76 X-RAY RADIOGRAPHY
  77. 77. 77 X-RAY RADIOGRAPHY  Radiography is an imaging technique that uses x-ray radiation to view the internal structure of an opaque object  The X-rays that pass through the object are captured behind the object by a detector
  78. 78. 78 X-RAY RADIOGRAPHY X-ray of Broken Handrail Bracket
  79. 79. 79 X-RAY RADIOGRAPHY How Do I Use Occasionally used to determine if cracks are prevalent near a corrosion or product failure site, and if the cracks contributed to the issue
  80. 80. 80 SUMMARY
  81. 81. SUMMARY TOOL PRIMARY USE Optical Microscopy Document original condition (~2,000X) SEM High quality image of as-is surface (~500,000X) EDS Elemental analysis of surface Metallographic cross- section Edge view of sample AFM Surface features on atomic scale XPS Chemical compounds on surface
  82. 82. SUMMARY TOOL PRIMARY USE Confocal Microscopy Analysis of non-flat surface TEM Extreme detail – atomic sale AES Visualization of chemical elements on top atom layers FTIR Chemical analysis of organic material GC-MS Chemical analysis of volatile material – solids, liquid, gas XRD Composition of crystalline material X-RAY Internal cracks or defects in material
  83. 83. 83 SUMMARY  Forensic engineers have many technically-advanced analytical tools at their disposal  Each tool has its own unique capability to help determine why a product failed  Many of the tools are complementary  Frequently more than 1 tool is needed to get the whole story  It is to attorneys’ advantage to be aware of these various tools and capabilities to maximize the value of an expert to the theme of the case
  84. 84. 84 QUESTIONS Bob Iezzi rai-technical-solutions.com riezzi@rai-technical-solutions.com (610) 761-6721 Corrosion Paint Technology Metal Coatings Pretreatments Plastics Expert Witness

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