thank you to everybody in the audience for your
attendance and interest
this presentation came out of some discussions
that we had with david where
he indicated that the
as reliability division would be interested in
understanding a little more
about various test techniques
and so we put together
more or less a survey
to cover a lot of techniques
that we thought might be of interest
with the understanding that
few
if any
see now why didn't that move
here we go
okay
with a couple of understandings
1st that
there's going to be few of any commercial laboratories
offering all these techniques
and also much more can be said
about each of the tests so this is definitely a survey
but hopefully what we're doing
today is providing a framework
so that you can decide what tests are appropriate
for your particular situation
we are an independent
engineering and scientific insulting laboratory
unfortunately
tim hicks is was called out to the lab unexpectedly
but tim is our mechanical lead and I think is in a role
very much
to what many of you are involved in where
somebody presents a problem
a part
something isn't working right
and the question is why
and
so what tests can be done to
understand to get some answers
mike collar my colleague here specialized in chemistry
especially polymer chemistry plastics
and for non metal materials
mike is our go to guy
and then I specialize more in metals
so I think everybody is pretty familiar with
the basis for
protesting why is testing important
from our standpoint
testing is the cornerstone of the scientific approach
to solving a problem
so as I say if
you're presented with a
particular component
in particular issue that isn't working properly
many people will usually have some opinions
different opinions
so how do you decide
which opinion
is the opinion that will
that is correct
and will lead to the solution to the problem
and the way you do that is through doing some carefully
design testing
and see if the results of the particular test
support the opinion
it's a simple concept but oftentimes we find
that it isn't followed
very well a lot of times so much
energy and cost is spent debating
where oftentimes a few carefully
designed and conducted tests will lead to the answer
and just a little bit of background material
the tests
that are performed the tests will be talking about
today
there's a number of organizations that promulgate
standards standards both for tests
as well as for specific materials
that are used in the different industry
and here we just have a few of them
and I think
most of you are probably familiar with these
some of these organizations
there's also international
organizations that promulgate gate standards
especially important
when you're in the international market
part of the standards setting function if you will
is the laboratory that is doing the testing
needs to be needs to be accredited so
if you're
going out to get some work done whatever that might be
you want to be sure
that the laboratory is
following the proper procedures
so that their results will stand up to scrutiny
because as I say
typically there's going to be different opinions
so when the tests are conducted
the important thing is that if somebody else
another party
another party in your company
has similar tests
conducted that the answers come out the same
there's lots of things that affect that
making sure all the measuring equipment is calibrated
making sure that the test
procedures are carefully specified
and carefully followed
and so that's what these accreditations are all about
the some of the accreditations are industry specific
and some may be
company specific
so some of the larger companies have their own
very detailed specifications
for materials
as well as for testing
types of testing
a lot of times you hear the word failure analysis
or root cause analysis
we really
believe it should be called product
performance analysis
because materials
and the components that are made of those materials
they don't really
fail in the sense that they did try hard enough
or they didn't prepare
they respond to their environment
and so if something breaks well
it means that it was overloaded to
a load which created a stress
which is beyond the capability
of the particular material
in that particular situation
and there can be
combinations of effect so temperature can affect the
load carrying capability the material
an aggressive
environment can affect the load carrying capability
the material
that aggressive environment may be something
that was unanticipated
by the designer so
again something breaks why did it break
it's a simple question but the answer may be
quite complicated
we're going to focus today
on materials characterization
tests so these are
going to be tests that are generally applicable
to a wide range of industries
wide range of products
basically to understand the material
and understand the environment
in which that material
is performed and this includes analytical chemistry
analysis of metal composition
crystal structure microstructure
we're going to be using microscopy surface analysis
and
also the mechanical properties
are what are affected by the material
structure
and chemistry so mechanical testing will also be
part of our discussion today
we're not really going to talk about
specific product testing
which is another
whole area just
by limits of time available
but obviously
there's lots of tests that can be conducted
to understand the performance of specific
components in a
specific environment specific conditions
so I mentioned a moment ago
looking at different materials and the foundation as
my collar reminds me
whatever he has the opportunity
is that
everything is chemistry so we have the periodic table
most of the chemical
elements that are on this table are metals
which means the atoms are arranged in
crystal structure
and the electrons are not bound to a particular atom
that's why metals are generally conductive
electrically and also have good heat transfer
and that in non metals
typically the
electrons are associated with the specific
adam or molecule
we have a few that are considered to be between
the categories
and really the basis for the organic chemistry
and the plastic solvents fuels and really us
our bodies are made of combinations of
four main chemicals hydrogen carbon
hydrogen over here
and then carbon nitrogen and oxygen
so those
four elements are the basis for
the chemistry that we'll be talking about
for the most part we could add
sulfur and phosphorus 2
and this includes the structures of medical
medicine and pharmaceuticals as well so
with that 1st
we'll talk a little more about chemistry
and then we'll talk a little more about medals
okay
this is my collar speaking now
I have my background as chemistry
typically the testing that we do
can come in from many different
problem solving
task testing can be because of product failed
but could
also be that they're checking the specifications
see if a products meets his specifications
so I'm going to talk a
little bit about this testing that I conduct
in the area of organic or plastics or
organic materials
plastics
is where we'll start
plastics or polymers
is more general term for their polymers
are both synthetic and natural
synthetic polymers are things like
fabrics fibers
made for cotton wool
wood is considered a polymer
synthetic ones are the things that we make
that are the plastics that you're more familiar with
the polyethylenes
the poles propylene the pole whatever
so
because we looked at that periodic table
we mentioned
the four key elements of
the organic materials the generally made up of
carbons shown as the letter c hydrogens
shown as the letter h
the vertexes between
them don't label up
but those are carbons at the vertices
so I've shown you here what a polymer is
and many of you
probably
are very familiar with the term and what it is
but just to kind of get us all
the baseline polymers are made up of many
me or smaller
parts which are called the monomers
showed neoprene
monomer there
isoprene has five carbons in it
it's a natural product
it is the basis of
the primary product and natural rubber
but you get from the rubber plant
and when you connect up those
smaller ice misprints into long chains
they connect up and bond together
you form the longer chains and
shown there as a natural rubber
these chains can get very long
meaning hundreds if not thousands of carbon
links long
so you get very very long
and so that's how we connect up the
monomers the next thing we can also do to that
if we take natural rubber
and we've throws some sulfur into it and cook that
that's the vulcanization process
and that's where we get
the much harder tougher rubbers
that we see in things like car
tires the vulcanized rubbers
and as you see in the picture on
the right of your screen
you see the sulfur is kind of interconnecting
those long chains and forming bonds between those are
called cross linking agents
and that's what causes the rubbers and
terrorists get very hard
well just looking at that
structure there
we can actually do a lot of testing on those bonds
and see how many
bonds we have see what the elements are
contained in it
and so what we do a lot of testing is we look for
is sulfur material
how much carbon
compared to hydrogen is in the material
what are the types of bonds are between these materials
and that's the basis of a lot of the testing
we're doing
chemistry so what are the elements present
what is the bonding structure between it
if it's attached to something
what if for such as a coating if it's leg on top
what's the interaction between the two species
and choosing the right analytical technique to do it
I will say that there are literally
hundreds of analytical techniques we can go
and I we kind of categorized them here into
several sections
you know kind of talk
a little bit about some of these
as we go watch as some of the testing methods
in some of them that you
probably have heard and are very familiar with
and we'll tell you what they can tell us
some of the general concepts in
chemistry analysis is how does it interact with energy
how does the material interact with energy
the two forms of energy we typically
interact it with is
either thermal energy
where we heat it up
or we freeze it down
or cool it up
and the second one is
interaction of light light is a form of energy
or the wave spectrums being x rays or those
during forms of light
and we call that spectroscopy spectra meaning
the wave the
color the spectrum of light
and scope meaning to look at to look at with light
we also can look at we're not going to talk a lot
today about my cross but to look at with
your micro scale
views but we're going to talk about this section
here of spectroscopy a bit
these different techniques
we love to use acronyms
and we'll go
to the details of some of these acronyms
and what they mean
as we go forward
but we like to use acronyms for them
fta air is one of the more common terms
but these can also be combined
with some of these other methods
these methods down here
up here should be up here the hplc and gc
those methods are used to separate chemicals
most materials that you're going to buy are
formulations of more complex
formulations of simple things
and so we have to separate them out
and then we analyze using these
methods here in the spectroscopy for the individual
methods so
this side here come
shows how we can combine the different methods
in instruments to
accomplish a separation
and then an identification of our materials
so what I call the holy trinity of
my pal and my polymer work
whenever materials be analyzer tested
some of the three that I like to see very upright
fourier transformed into a red that's when we in pins
infrared light onto them material
and see how it responds to the infrared light
the ['one']millisecond is digital scanning calorimetry
how is it interact with heat
and ['one']millisecond the last one is
thermometer analysis
which is what happens when we
burn the material and what comes off
we'll show you what the value of each one of those
test methods I mentioned the term spectroscopy
which means
to look at with the spectrum and here's kind of a broad
view of the spectrum
with the visible light being right there in the center
now that's visible light we see with the
colors going from red to
violet
and above the violet
range
the shorter wavelengths we get into the ultraviolet
below it we get into the infrared
if you interact any
material with these waveforms or with this light
the molecules in them will absorb those
and the energy from that
wave function and they will start to
the bonds will start to vibrate
each bond type in a material will vibrate
with a different level of impingement
and so when molecules
gather in that infrared light
they tend to either take it or reject it
if they take it in that means it's absorbed
if it absorbs it it holds that energy in itself and
it usually is in some form of energy heating
now this is a statement fact as goes on with
global warming which we hear about a lot
it's when the molecules in the atmosphere
in the case we talk about a lot co2
are absorbing the ir radiation
and holding it
into the atmosphere rather and releasing it back out
so it can go back out into the
into space so when it holds the energy
it will vibrate the molecules
and that Southern molecules hold that energy
what do we get when we look at
something that's been interacted with
infrared light
what we get is
the points where it absorbs that energy
and they're very
very definitive points
because you look at the spectra that comes out
this molecule here is polyethylene plastic
very clean material contains only carbon and hydrogen
and it has
certain points where the hydrogen carbon bonds
will vibrate
and that's where it takes in the energy
because the hydration to go
and they occur right there around the 3 000 region
so when I see this double peak
I know that I've got a hydrocarbon based material
in general
I got some of the carbon carbon bonds way down here
this band so I see a thing that has
these simple bands these two appear in this
I know I'm dealing with a hydrocarbon
if I don't see anything
else or very little of anything else in the spectrum
I know it's pretty
much a pure hydrocarbon meaning contains only high
terminal hydrogen
in this case that's what polyethylene has a
that's the wavelength
these are the wavelengths in the lower level
and this is the intensity of absorption
and that also can be a quality quantitative
if we develop calibration curve for that
so we can quantify how much
each one of those contains
infrared transformation
for you transform infrared spectroscopy
is a classic tool
you're gonna see it in a lot of the analysis
and testing people
will do for you
typically will characterize what the material is
there's literally
millions of compounds that have been database
and so we compare them like the fingerprint
libraries that we use
we often call us the fingerprint of a molecule
and then when it's compared to the fingerprints in the
largest millions of compound databases
it will come up and say it's most likely what you have
is for example polyethylene
it can also identify trace contaminants in it
and I'll show that here on the next slide
the show of the top to want to show you before
this is pure polyethylene up on the top
very clean you look at the baseline
the baseline by the ways at the top
of this slide where it's very flat across the top
except for those few peaks that
come out in the 3 000 region
and the 1500 region
then you look at the one of the bottom
this polyethylene has contaminants in it or
it can be added to it
but that baseline is very rough
and these extra peaks that we're seeing at the bottom
pointy picking up here
those are generally the contaminants or
additives that have been placed in the material
so it is helpful when I don't see a clean
when I get a polyethylene
that is supposed to be a pure polyether material
quite often
such as things that might be used in food
products or stuff
we try to keep them pretty clean
and we see these contaminants showing up
we generally know that we have an off spec or
not a quality material we're using
so that's what infrared can tell
us it strengths is that it's capable
of identifying organic compounds
by their functional groups and how the
bonds are attached
and that it can be compared to huge libraries
extensive libraries
and it literally takes a matter of minutes before to
do this spectra
compared to the library
and then giving answers to watching material is
so it's a very
fast and rapid technique
done an ambient conditions
it can be done in very small samples
it can be done
both liquid samples solid samples
and it can be quantitative
it does have some limitations
it's not as good doing surface analysis
but it can be done
it does requires calibration curves
if you're going to do quantitative analysis with it
and it's not really that useful for
metallic materials so it's really based
this real basis is for
because the metals don't have bonds
they don't have the same type of monster vibration
['one']millisecond has said differential scanning calorimetry
that is classic calorimetry that you
might have done and I'll show you example
that you might done in high school fluidly
adding heat to something
calorimetry is when you put heat into
something and you measure the
effects of the product out heat
what I like to use
is an example of this is when you put
an ice cube
into a container
and you measure the temperature as you go
from
below 0 0 centigrade
and you start to elevate that temperature
you hit the point at zero
and you're going to see a transition
as it melts
and then you can continue to heat up that water
that's water
you need to heat that water
and it will do another transition at
100 degrees in a great
and that's the point at which it boils
and so we see two transitions with water
and so if I put a material
a solid material into a
calorimeter and I heat it up
and see those two transitions one at 0 1 at 100 degrees
I'm pretty confident that I'm dealing with water
we get complex materials
you'll see many transitions that occur
and each material is carrions can be characterized by
this method
it strengths as they can do it with small samples
the size of literally a fraction of a pencil eraser
and it heats up
but it can give you very
accurate measures in the face transition
so what this is measuring is really phase transitions
all materials typically have some phase transition
even metals will have face transitions
plastics go through phase transition as it either melts
or become soft
when it goes through it's what we call it
either the glass or the melt transition phase is it
softens up
and that's what we look for
in this
tess
it is destructive in nature its limitations
it is destructive in
nature it does destroy the material
there's no direct
elemental information
simply telling you how the material will behave
in performance
environment
so here's an example shown here on the slide
going from left to right on each one of these two is
the temperature that we're
elevating it up to
we're ramping up the temperature
as it goes up in temperature
it literally will see this transition that occurs
on this one here for polyethylene
and we know that
temperature and I can't really
can we get a close look at it
it says this transition peak is 128
that is a transition for classic polyethylene material
by the way polyethylene has many variants of it
and so this can also be a method of testing
what variation we had we know this fantasy
polyethylene
low density polyethylene
ultra high density polyethylene
so it's all different kinds of polyethylene
and this is a great way to separate out those different
polyethylenes because
they generally have a different transition point
on each one of those
it will have a different
slight transition point as we pull it down
so there's a heating process
and then we can take it backwards and we cool it down
and see the return transitions
it starts to lock itself up again
this is also useful
information in the processing of these materials
as we watch for these transitions
as we melt the materials for injection molding
we also set our
standards for operating or use of the materials in
the application
you want to stay away from that transition point
for most materials
so it doesn't end up
having
a bottle or something that you're going to package
something and then ends up melting
because of the way it's being stored or used
in the third
technique that we use
is that I like
to do in my base
testing of a materialist thermogravimetric analysis
this is literally taking the material
by burning it or decomposing
it either on your burning conditions or
combustion conditions
meetings in an atmosphere that has oxygen
or in an inverted atmosphere for its decomposing
meaning it's in nitrogen or some other atmosphere
where it's decomposing
the material
we like to take these from the value of this
math
is that it can actually tell us what the elements are
in material if we do analysis of the gases coming off
you can tell us the thermostability of material
you can also tell us what volatiles and
non volatile materials might be in a material
almost all plastics
of some kind of plasticizing agent in it to keep it
flexible or something like that so
those are all going to come off
and then we're going to see other
things that are left behind
we call those the residues
and what those contain
elementally
I'm just going to kind of
flip through here and show you this
example what we have
this is again
temperature in the x y direction as we heat it up
I'm going to look at this top
very top where you see a line going from the top left
as you follow that along
you're going to see that line that goes across
and we see at a certain point here
we start to see
we're losing weight the
y axis here is the weight of the material 100
of the material to zero
and we see that
as the product is getting hotter and hotter
heating it up
obviously we see we start to lose material
and those 1st
losses are probably
the volatile materials coming off of the plastic
can be powered polymerized
ethylene it could be
additives that have been put in it could be water
and in this case here it measures
it may be difficult to see on your screen here
but it says about 5.3 %
of this initial weight came off here
early on and then we see a big transition that occurs
where we lose about 80
another 70 of the material
comes off in this phase here
that's your polyethylene coming off
we can analyze those gases
and sees the carbon and tighter in coming off
and then we see we got in about a 6% left
at 6% loft at the bottom of this
is our residue and that generally is an additive
so when you see a polyether
it might be a white who like
such as an a white
plastic bottle used for bleach or something like that
they usually add titanium dioxide
into that and those
are the residues that we'll see at the bottom
most internet next
all those can be analyzed
to see what's in the material
and then the next thing I'm going to talk
about is how you take
a more complex material and separate it out
we use a method call you the chromatography
it's called chromatography because
the way it was initially applied
this is in the picture in your top right
you're going to see
the classic cal symmetry where you put an ink dot
for example on a piece of paper
and you put that paper piece of paper into a solvent
and let the
salmon wick up that piece of paper
and as it wicks up that piece of paper
it will separate out the different colors in your ink
you will see these dots because some
dies are slower
moving up that wicking process and others
and so you see this
chromatogram
or the separation of the colors separation by colors
that's the classic one you might have done
in high school
a great school
it's got much more complicated
we're instead of running it up a piece of paper
we send it through a tube that is lined with those
kind of
absorbent materials and we sent it through tubes
that one in the bottom
picture of the bottom left is a tube that's about
two to 3m long
and the one on the right at the bottom right
is a tube that is about
60 meters long
so you can get very very long and very very thin
and we run it through
and what we get out of that
in the process of sending a material through these
long tubes and columns coated
here's a plastic at the top
this is a polyether plastic from a
packaging bag
we grounded up frozen and grounded up into samples
and we put it through liquid chromatic
if we saw put in the solvent
put it through liquid chromatography
and what you see in the bottom of the curve is by time
on the x axis
you will tell us in the evolution in minutes
how much
lucia peak
and that peak is one substance coming off the column
then we see some
smaller peaks
we see another peak
as you follow these peaks
we'll see all the different
materials in that plastic that are coming off
that plastic contains about tough
10 additives to it
everything from antioxidants to uv protection agencies
to slip agents
to thermal
protecting agents so there's a lot of additives in it
I can take
each one of these peaks and send it through a second
thing such as fit r which I mentioned before
in this case we sent it through a
mass spectrometer
and it will actually identify each one of those peaks
so in other words
that 5min coming off the column and
identified it as ergonomic
which is an antioxidant
and it sees other compounds within it
diamonds of organ axe
it sees some slip agents in there and see some guy
another anti accent they had in there
they had a heat stabilizer in there
so this is a way to separate everything
out within a complex formulation
like a plastic
into its innovative components
and then analyzing each component for what it is
so this is best used for reformulation techniques
and also quantifying and testing
whether the formulations were properly formulated
classic techniques to there
that I'm going to turn it back to Dr
shipley here
and he's going to talk about the medals analysis
because these are medals medals
okay well thank you and
as I said at the beginning we're
giving you a lot of information very quickly
trying to do a survey of these different techniques
and also providing some basis for
you to do your own research and get further information
the other point to be made is that
we're thinking of these techniques
from a quality standpoint
because obviously that's our audience
but the same techniques
can be used in many other applications so if you're
trying to identify
for example
you have a sample of material you're trying to
identify where did this come from
who is a manufacturer
if you compare it with a known sample
and you compare the unknown and see if
the formulations match up as
mike described a moment ago
as we're watching
television in the evening
the people that do
the writing for the
inc are fascinated by mass spectroscopy
so it seems at least every other episode
they're analyzing something in the mass spectrometer
and that provides
the critical evidence to solve the case
the only difference is it takes a lot more time
than it does on the tv show right
but anyway
so let's talk a little bit about
about the metal materials now
and
similar concepts
we're interested in composition so we're interested in
what chemical elements
are combined in a particular sample to provide the
to make that particular alloy
so there's a technique called optical
emission spectroscopy
where you
generate a spark and then look at the spectrum
of the radiation that's coming off
and each element has characteristic
radiation that it emits so you can identify with the
appropriate standards
you can identify
what is the composition of that particular alloy
we can also through a process called metallography
look at the crystal structure how are
the atoms combined to form crystals and different
phases or different
crystals that make up the microstructure
and that gives us information on the properties
and the heat treatment
we can go and look in the electron microscope
and look at very high magnifications and
also do elemental analysis
and we'll talk about that
and a little bit more detail in a moment
mechanical properties
hardness is a good indication
of the strength of the material
it's the resistance
to
surface
being indented or penetrated by a specific geometry
of indenter under a specific weight
and that's related to the tensile strength
that is the strength of the material its resistance
to a uni axial load
and an impact testing is another type of test
which measures not so much the strength
but how much energy is absorbed
when the material fractures
and
with respect to impact testing for example think about
the difference between a water
glass and a tin cup or metal cup
the reason why metals are so
useful as structural materials
is not only strength
but also the fact that they will deform
before they fracture
in comparison to say glass
for example should just shatter
so talk about elemental
or insight optical emission spectroscopy
different ways of generating the spectrum
and here's an example
of what that looks like
it is destructive in the sense that leaves
a mark on the surface
and you can see where individual little arcs have
attack the surface are left a small pit
because the material is
actually melted and vaporized by that electrical arc
so here's a few in limitations it is
destructive as I say in different
ways to prepare the sample
the one I showed you a moment ago
was on a flat surface
and there can be some
complexity sometimes in interpretation
and also in steels
carbon is very important to understand the
composition and grade of steel so carbon nitrogen
hydrogen oxygen
are not
easily determined with this particular technique
so there's other
techniques used to determine the carbon
content of steel
you can also use this technique for example
the quality of drinking water
are there any dissolved minerals led
in drinking water is a big problem
in many areas so
we can use this technique to analyze
any contamination of water
and as I say
the chemistry of structural material steel aluminum
copper whatever
metallography
so we take a sample
and we embedded in a resin 1st
for handling and polish it to a very fine
surface finish
and then we can etch it with an appropriate acid
and bring out the crystal structure
the grain structure
if there's any secondary components secondary phases
you can look at things such as cracks or corrosion
and also if the material has been plated or has
some surface hardening
for this so metallography is one of the
standard procedures for a metallurgical analysis
there's special microscopes
to examine these polished specimens
and the scanning electron microscope can also be used
here's
so there's also for many materials
there's what's called cleanliness so
absence of any harmful inclusions or harmful
2nd phases if you think about
for example
peanut butter that has
the peanuts embedded in the peanut butter
so that would be an example of the second phase
also for joints welded joints braised joints soldering
issues involving processing
here's an example of
a microstructure
believe this is a bearing component
you can see that there's been some kind of surface
damage here something happened to cause this
area on the surface to have a different microstructure
and then there's also a developed
in this particular sample and of course the thing about
cracks I'm sorry I said bearing but this is actually
a wire rope this is the individual wire
that is in a wire rope
and
showing that there's been some damage to that wire and
the crack as I say
and the thing about when you see cracks
oftentimes when you have a fracture
it's very difficult to understand
looking at the component that's already broken
and damaged but
you can oftentimes learn a lot of useful information
by looking at
similar components
where the crack has not progressed all the way to
complete failure
metallography relatively simple quick
but you have to have people that are very skilled
technicians because
if the material isn't properly prepared
there can be problems in interpretation
and you can get misleading results
so
there does need to be a
good amount of care in the sample preparation
for example if you're cutting
you want to be very careful that you don't overheat
the sample
a few words about stereo microscopy
we can learn a lot of useful information
just by looking
at the sample whatever it is or the broken component
under the stereo microscope
so stereo microscope is off the first step
in solving the problem
looking for such things
as does the sample appear to be uniform
are there differences
different areas of the sample different
tints or colorations
for looking at particles
are all the particles of same size
are they all the same jake
or not and if
you can also under the stereo microscope separate out
different areas or different
samples for further analysis
so for example
as mike was discussing a moment ago
if you have some plastic materials
you might look at them under the stereo microscope
and select different
pieces are different
samples that you're going to run your ftir dsc and tga
scanning electron microscopy
produces images that look very
much like what you would expect to see
if you could
image under theatrical microscope
with bear it with much better depth of field
when we think back perhaps to high school science class
optical microscopes
you go up to very high magnifications
but they require the sample to be very flat
so
one of the strands of the scanning electron microscope
is that you're able to
have good resolution and good depth of field
so it's very well suited for
rough samples
fracture samples
things of that nature
and you can get very detailed images
at very high magnifications
you also can use a technique called energy
dispersive x ray spectroscopy
and that tells you
what elements are present on the surface
so if you see
something on the surface and the
scanning electron microscope
and you say well what is this what's it made of
you can identify the elements and that
doesn't give you any further information in terms of
compound identification
but it does give you the elements
and then
you can select that area for further analysis
if necessary
so
one of the limitations is
because the
scanning electron microscope images are only
black and white
there may not be as much contrast as you expect to see
an optical microscope
also the
scanning electron microscope to sample has
to fit in the vacuum chamber
so you may need to do some cutting
to allow to allow the area of interest to fit inside
the vacuum chamber
here's an example
of looking at the surface this is the
this actually the bearing component
so when we looked at the
bearing
component under the scanning electron microscope
we see here that there's
something going on at this particular location
we're starting
to develop a crack and of course the thing about cracks
is they don't get any smaller they don't get bigger so
this would be
the beginning of a failure in that particular location
okay I mentioned a moment ago so eds
can give us an indication of the chemistry of the
particular
surface now it's very important to realize that the
eds you're only looking at the surface
because it's the interaction
of the electron beam
exciting the electrons
on the surface and those
electrons is they
transition to the different
electronic shells that give off
x rays that are characteristic
of that particular element
so
so it gives you elemental information
and here's an example
only the elemental information on the surface
and a little bit
subsurface to the extent that the electron beam
can penetrate
into the surface
so here we this is an eds of a
particle that was found on the surface of a steel part
and it was found that this
particle we say well what is the particle
and it turns out to be a copper
copper rich particle
so we see the copper peaks here
the iron peaks here
there's also a sulfur peak here
and the sulfur peak would have come from
the lubrication
so we're identifying in this particular case
the system
you had some copper containing components in the
system and particles are coming off of there
and then they're being deposited on the steel
so this would be an example of analyzing some
components that come out of a
like a bearing or a gear
in some piece of machinery
the other thing is
because you're combining the two techniques
you have the capability to go to very
high magnification
so you can see a very small particle
and analyze just that particle what is it
and the
scanning electron microscope and then eds is the most
scanning electron microscopes
I've encountered have the eds capability
so you can do a quick look
at the sample in the sem
and also gets an elemental information
you can also get a semi quantitative
indication so is this material the right alloy
if you're concerned about
determining does the metal
meet the exact specification
then you need to do an optical emission
but if for example you want to
distinguishes
this is supposed to be an aloe deal
does it have the appropriate
chromium nickel
whatever other alloys you're supposed to be present
you can do a quick check
in the eds
I mentioned the limitation for the sem this
sample size and vacuum chamber
so that also applies here
and
you do have some complexity with respect to the
peak overlap so
you know these peaks come about from the
electron shells
and so
each particular atom has
several electron shells
various peaks that can be generated
so sometimes you get confusion
that has to be sorted out by an experienced analyst
for example malibu and then when sulfur
have peaks that are very close to each other
so you have to be careful that you're not
confused by that
okay let's talk a little bit about hardness testing
and there's a variety of hardness tests
depending on what type of indenter is being used
and what was being measured so for example
micro hardness
is
two types of general use
one is called new which is an elongated pyramid
and then vickers which is a
uniform sided pyramid
in winter that is pressed onto the surface
under a particular load and then the dimensions of the
indent are measured
and that gives us an indication of the hardness
on a particular scale so
all of these
scales they're all relative to each other
they don't really
you know
there are tables for converting from one to the other
that is on a
basis of people that run a lot of different tests and
see what the correlations are so it's
it's very much a specific procedural technique
rockwell is another very common one
which measures the depth of the indentation
and there's various scales for rockwell
so one is with a conical indenter and another is with a
16
of an inch diameter ball a debtor again under specific
weight and measuring the specific depth of how deeply
earth specific depth
of the indent
bri now is measuring the diameter
of a 10 millimeter ball under
specific load and
how large is the diameter of the impression that's made
so again we're measuring
depending on the sample
what is appropriate for that particular
for that particular sample and also
are their specifications frequently though
will be specifications
to what
the hardness is supposed to be
for that particular product
so it can be it's a very quick check
even though it does leave a little dent if you will
on the surface
it's generally considered to be not destructive
so you can use it
to check if parts are properly he treated
there are correlations with tensile strength
for specific materials
and if we have a surface hardening
technique such as carburizing or fighting
you can look at the hardness layer how deep it is
and
what's been achieved by that particular heat treatment
and then also
this technique can be done in the field
so you can go out
and do tests on components that are in service
with your reading equipment
so
we have good
you know capabilities a good quick test
portable as I say
scales are arbitrary
there's no direct correlation between the scales
so typically you're going to see
the specification that talks about a specific
specific value with a specific test a
specific procedure here's an example of a vicar's
impression
and here's an example of
just a practical failure analysis if you will this is a
manufacturer of steel parts and they thought that
a little
increased hardness and increased strength
would be a good thing for these parts so they made that
change and ship the parts to the customer
customer didn't realize that the hardness had been
changed
the supplier thought the higher strength was good
but then they
didn't realize that that
meant that these parts were susceptible
to stress corrosion cracking
hydrogen and belittlement
and they experience delayed failures
and why didn't know why so
a quick hardness check
showed that the materials were harder than expected
and were susceptible to environmental attack
tens of testing I'm gonna skip over this I think
because we're running close to our hour limit
so certainly
you can download the slides and look at that
for at
your own time
do I say a few words mike about these other techniques
I just quickly say that coding's surfaces
are usually analyzing a little bit differently
it's usually an engagement of the surface with
something like a secretarian
spectroscopy against spectroscopy is some weight
form usually light or something like this in this case
here it's it's these methods here in the x ray
xps is an x ray impingement on the surface
it gives you a spectrum back
to look at so these are surface analysis and this
sometimes used in codings
or in just looking at the
integrity of a surface for corrosion
stuff like that
so we have a
yeah I'm not sure we want to go into that
we have time for the details of this here
but again it can detect very low concentrations of
of dopant or impurities on the surfaces
so let's just keep going for the time there
so basically you're extracting
adams from the surface and analyzing yeah correct
a little
okay and then x ray
photo electronics trask again
this is showing down on the bottom left
that you know how it's done
actually impinges on the surface of that
actually releases electrons
those electrons can be translated as it shows there
in the spectrum
each one of those peaks is that specific
elements such as
silicon carbon
tin nickel
fluorines
all those are different pieces telling us what the
concentration is and what the
elements are on the surface of that material
so the point being that the surface may be a different
chemistry than the bulk of the material
and this is how depending on the application
you could figure that out
okay in corrosion
again and if there's a corrosion product the surface
of the material
the question is what is that
first of all
what is the corrosion product and what caused that
and so again we would use these
techniques that we've been talking about
to analyze and determine what is the environment
that reacted with
the metal to cause corrosion now we use corrosion to
think about metals
plastics are also subject to environmental attack so
again the concept is very similar
the environment is reacting
with the product at the surface
there's a chemical reaction of some type
in case of corrosion it has to do with electrochemistry
and ions and electron transport
so on and so forth in the case of
plastics it's a little bit different
but it's still a chemical reaction
occurring at the surface of the material with the
environment and usually
you don't want
your prod to be reacting with the environment
that's a bad thing and immediately the
materialism right or the environment isn't
what the designer anticipated
we use a term failure analysis and
the key here is that any and all of these techniques
may be appropriate in a particular failure analysis
depending on the product depending on the material
depending on the circumstances so generally
as I started to say at the beginning
the question is what is the
material is the material what it's supposed to be
chemical composition in structure and properties
is there something that might have
occurred in the manufacturing process to
cause a change in the material or change that
from what the design are anticipated
and then you look at the same question with respect to
the environment which includes
loads stresses includes different types of stresses
includes a temperature includes a chemistry
and then if both of those appear to be okay
then you have to look at
what are some of the other factors
that might have caused a particular problem
is there something the operation or the maintenance
is there some combination of factors
and for example we had a case
where we had some plastic tubes carrying a water
based solution
and these plastic tubes are leaking out in the field
which is a big problem
you examine the fracture surface
and saw an evidence of environmental stress cracking
and that was they were able to identify
the contaminants that were reacting with that plastic
and so just who we are
professional analysis
key thing to understand is oftentimes the laboratories
that conduct these tests
different than the people
that specializes interpretation
so it's often required to have a team approaches
I say the first part of the team is to have
a very confident laboratory that's accredited certified
going to do the work and do it right
so that the results are reproducible
and then to understand
what it means by interpreting the results and
knowing the literature knowing the material properties
so I thank you for your attention
I know we've covered a lot of material
hopefully everybody has been able to
find something of value
and happy at this point answer any questions
thanks rock and mike
there were a variety of questions
some amount of context but there was one on fit are
asking can fit are differentiate between isomers
it's difficult
but it can so if you're talking about
different ice mars or like string
for example it's difficult
the bonds themselves are usually the same
but sometimes they're in different configuration
that's what ice marks different configurations
so with very very careful analysis you can
but it's not the best technique for
isolating ice marks
in combination with some of the other
test methods for example quite often isomers will
demonstrate different thermal properties such as
the dsc
that digital canadian difference is gaining calorimetry
so a combination
is it can be used yes
another question was
what kind of a test would you initiate
for the composite
plastic material
as part of a reliability degradation test
and so composites are
of course usually accommodate
where they are by definition of combination of
multiple components
usually we have to take those components apart so
posits are much more complicated analyze
for example if you have a glass composite
you got the resin
you're going to analyze the resin
that's going to be dumb with the classic polymer
techniques fta rag
that seems like that
I will say that
because a lot of those
have thermal plastics that are highly cross link
that honestly melt as well
so so it's a little bit different
and then you got the glass or the
other component the strength component of the composite
you see usually have to separate that out
a bit the most
important thing to try to get your hands on
sometimes is the interface between the two
whether you got a sizing aide between the
soft and hard parts of the composite
so it's a little bit more tricky
but
those are the basic techniques
that
we look at
the other thing I'd add to that that's very
important and this is
in the design phase if you will
is to specify the materials
very carefully so that
because one of the problems that you sometimes see
is that a material specification will be a loose
for example and then the supplier changes
or that particular supplier changes
something in what they're providing
and so now you have a problem
where you didn't have a problem before
and it's because
the material specification was a little bit loose
and so you're getting something that still
meets your spec
but it's different than what you used to be getting so
things I'm composites what's the
you know the orientation of
the different components and how
how is that determined to whether it's proper or not
do you do it structurally do you do it
with some mechanical property testing do it with some
chemistry testing as mike was describing
some things like the tga method which is you literally
burning or decomposing material
you'll see the resident left behind is you're
quite often in organic classes and stuff like that
so that'll give you the percentage qualities
so kind of you can use some of these same
techniques for composites
that's great commentary because in a
in a global economy where we're sourcing all
over the place at multiple tears
that you never know what you're gonna get
unless you're testing for it
well
that's correct and that's why
we said you know where do you test
you prefers
to use the testing methods to set your specs
I always like to set your spec
so that when you get the materials from globally
you can compare we do that quite common
that's a common problem with a dress here
is that someone will send us a product that are they
on stack for what I asked them for
because we're getting it from a different source
materials are different
from different parts of the world
because their law materials are different
from different parts of the world
so you gotta watch that's
there was a lot of
news some years ago about drywall that was sourced from
China for example and because the mind
it supplied the gypsum had some impurities in it
that this created problems
in the drywall after was installed in homes
so
but again it's it's
that's why we
mentioned the presentation at the beginning
the idea of the specifications so that you
whether if you're a supplier or if you're the
the customer
there has to be good communication
what exactly is needed
so that the supplier can
meet the requirements of that particular product and
obviously the tighter the specification
that's going to affect the cost
so you don't want to include things
that are not necessary
but at the same time you want to be sure
that the end of the day
everybody understands what's required
yeah very good comments
I see
we're losing her audience because we're after the hour
but I did want to run a couple more polls
so
let me launch this off to see if we can get a response
as to how the information flowed I think it's
great coverage and
because everyone has copy of the slides
they could pull it off of the handouts tab
and makes a nice
desk reference
certainly a contact information is there so
if it comes down to specific topics or issues
they can contact you directly
they can contact us or they
as I say
there's many laboratories that conduct these tests
and
hopefully the supplier
if you're
dealing with the supplier of plastic components
hopefully they're going to be familiar
with the
tests that are appropriate for their
particular product
so
you know obviously these are not
these are not secret
ideas in any way shape or form but
you have to have people that are familiar
that's where we see the biggest problem is
as I said the example of the
manufacturer make you change in hardness
they just didn't know
the consequences of making that particular change
so I think we pretty much hit the target here
people are pretty happy with the presentation and the
coverage that we gave it
and then there's one more slide that I'd like to run
do I
see if people have any
particular topic
you're gonna comment
I just say it says organizer on my screen
says organizer
must close pole to enable screen sharing
so I think you need to take the screen again
yeah you can see the pole
okay though
so I don't need to take the presentation token
okay
we're starting to get
lower participation
I think people are moving at other meetings
we'll just give us an idea of what
those sensitive areas are
it looks like structural integrity is by fire
more concern than chemical and polymers metallurgy
so before I close
I'd like to thank our presenters on behalf of
the astra reliability
risk division
and on behalf of our audience
and I hope that you guys will come back
and do a presentation for us in the
near future maybe
I'm one of these particular topics
like structural integrity
which seems to be pretty popular
and if that will close the webinar
because we're about 10 after
so thanks again
rock mike and regards to tim
we'll end here
and again thank you david and thank you to
everybody that attended and hope that
we provide some useful information
whatever your industry whatever your discipline
have a good rest of your day great thanks