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HELPFUL
INFORMATION
FOR ATTORNEYS
WHEN WORKING
WITH
FORENSIC
ENGINEERS©
Dr. Robert Iezzi
Docs > Iezzi Webinar.pptx

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OUTLINE
 What Do Forensic Engineers Do ?
 Types of Analytical Tools Commonly
Used
 Case Studies
 Summary

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WHAT DO FORENSIC
ENGINEERS DO ?

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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

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ANALYTICAL TOOLS

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INITIAL SAMPLE OBSERVATION

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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)

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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

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OPTICAL MICROSCOPY

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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

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OPTICAL MICROSCOPY

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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

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SCANNING ELECTRON
MICROSCOPY (SEM)

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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

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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

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SCANNING ELECTRON
MICROSCOPE

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SCANNING ELECTRON
MICROSCOPY (SEM)
Smooth metal facets
characteristic of
brittle fracture

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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”

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ENERGY DISPERSIVE X-RAY
SPECTROSCOPY (EDS)

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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

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ENERGY DISPERSIVE X-RAY
SPECTROSCOPY (EDS)

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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

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METALLOGRAPHIC CROSS–
SECTIONS

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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

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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

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METALLOGRAPHIC CROSS–
SECTIONS

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METALLOGRAPHIC CROSS–
SECTIONS
How Do I Use
Frequently
Particularly to determine why coatings fail
or corrosion mechanisms
Used with SEM or other tests methods

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CASE STUDIES USING
THESE ANALYTICAL
TECHNIQUES

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CASE #1
CORROSION OF PAINTED
ALUMINUM WINDOW &
DOOR FRAMES

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CORROSION OF PAINTED
ALUMINUM WINDOW FRAMES

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CORROSION OF PAINTED
ALUMINUM FRAMES

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CORROSION OF PAINTED
ALUMINUM FRAMES

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CORROSION OF PAINTED
ALUMINUM FRAMES

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CORROSION OF PAINTED
ALUMINUM FRAMES

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CORROSION OF PAINTED
ALUMINUM FRAMES

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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

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CASE #2
CORROSION OF COPPER
ROOFING COATED WITH
LEAD

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LEAD-COATED COPPER

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LEAD-COATED COPPER

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LEAD-COATED COPPER

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LEAD-COATED COPPER

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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

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CASE #3
MANGANESE
PHOSPHATE
COATING

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MANGANESE PHOSPHATE

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MANGANESE PHOSPHATE

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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

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CONFOCAL SCANNING OPTICAL
MICROSCOPY

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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

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CONFOCAL SCANNING OPTICAL
MICROSCOPY
Partial profile of 1-Euro coin

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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

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ATOMIC FORCE MICROSCOPY
(AFM)

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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

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ATOMIC FORCE MICROSCOPY
(AFM)

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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

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X-RAY PHOTOELECTRON
MICROSCOPY (XPS)

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X-RAY PHOTOELECTRON
MICROSCOPY (XPS)

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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

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TRANSMISSION ELECTRON
MICROSCOPY (TEM)

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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

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TEM

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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

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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

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AUGER ELECTRON
SPECTROSCOPY

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AUGER ELECTRON SPECTROSCOPY

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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

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FOURIER TRANSFORM
INFRARED SPECTROSCOPY
(FTIR)

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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

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FOURIER TRANSFORM INFRARED
SPECTROSCOPY (FTIR)

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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

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GAS CHROMATOGRAPHY MASS
SPECTROMETRY (GC-MS)

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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

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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

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X-RAY DIFFRACTION (XRD)

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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.

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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

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X-RAY RADIOGRAPHY

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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

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X-RAY RADIOGRAPHY
X-ray of Broken Handrail Bracket

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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

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SUMMARY

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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

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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

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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

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QUESTIONS
Bob Iezzi
rai-technical-solutions.com
riezzi@rai-technical-solutions.com
(610) 761-6721
Corrosion
Paint Technology
Metal Coatings
Pretreatments
Plastics
Expert Witness