Vielitzer Stra

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• Vielitzer Straße 43
• 95100 Selb
• GERMANY
• Tel. [phone]
• Fax [phone]
• Email info_at_linseis.de

Linseis Inc. 20 Washington Road P.O.Box
666 Princeton-Jct. NJ 08550 Tel. (609)
799-6282 Fax [phone] Email
info_at_linseis.com
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The Company

• Since 1957 Linseis Corporation delivers
  outstanding service, know how and leading
  innovative products in the field of thermal
  analysis and thermal physical properties. We are
  driven by innovation and customer satisfaction.
  Customer orientation, innovation, flexibility and
  last but not least highest quality are what
  Linseis stands for from the very beginning.
  Thanks to these fundamentals our company enjoys
  an exceptional reputation among the leading
  scientific and industrial companies.
• Claus Linseis
• Managing Director

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ASTM E 1461 - 01

• Standard Test Method for Thermal Diffusivity by
  the Flash Method
• A small, thin disc specimen is subjected to a
  high intensity short duration radiant energy
  pulse. The energy of the pulse is absorbed on the
  front surface of the specimen and the resulting
  rear face temperature rise (thermogram) is
  recorded. The thermal diffusivity value is
  calculated from the specimen thickness and the
  time required for the rear face temperature
• rise to reach certain percentages of its maximum
  value. When the thermal diffusivity of the sample
  is to be determined over a temperature range, the
  measurement must be repeated at each temperature
  of interest.

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Terminology

• 1 Definitions of Terms Specific to This Standard
• 1.1 thermal conductivity, l, of a solid
  materialthe time
• rate of steady heat flow through unit thickness
  of an infinite slab of a homogeneous material in
  a direction perpendicular to the surface, induced
  by unit temperature difference. The property must
  be identified with a specific mean temperature,
  since it varies with temperature.
• 1.2 thermal diffusivity, a, of a solid
  materialthe property given by the thermal
  conductivity divided by the product of the
  density and heat capacity per unit mass.

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Classification of some Thermophysical Properties
Thermophysical Properties
Thermodynamic Properties
Transport Properties
Thermal Diffusivity LFA
Specific Heat DSC
Thermal Expansion Dilatometer
Thermal Conductivity
Mass Diffusion Coefficient
Electric Resistivity
Kinematic Viscosity
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Thermal Diffusivity Calculation

• Calculation
• First determine the baseline and maximum rise to
  give
• the temperature difference, ?Tmax Determine the
  time required from the initiation of the pulse
  for the rear face temperature to reach ?T½ . This
  is the half time, t½. Calculate the thermal
  diffusivity, a, from the specimen thickness, L
  squared and the half time t½, as follows
• ? 0.13879 L2/t½

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Determination of Thermal Diffusivity
The quantities measured are temperature (T),
time (t) and voltage change (?V). Note ?V
?T.
Experimental Data
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Measurement Schematic
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Real Measurement vs. Adiabatic
The two graphs show a true measurement vs. an
ideal case of no heat loss (i.e. adiabatic) The
difference between the two must be accounted for
using the correction models contained by the
software.
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Significance and Use

• Significance and Use
• Thermal diffusivity is an important property,
  required for such purposes as design applications
  under transient heat flow conditions,
  determination of safe operating temperature,
  process control, and quality assurance.
• The flash method is used to measure values of
  thermal diffusivity, a, of a wide range of solid
  materials. It is particularly advantageous
  because of simple specimen geometry, small
  specimen size requirements, rapidity of
  measurement and ease of handling, with a single
  apparatus, of materials having a wide range of
  thermal diffusivity values over a large
  temperature range.

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Thermal Diffusivity

• It is a measure of how well a material can
  transmit heat under transient conditions. Since a
  material does not just transmit heat, but must be
  warmed by it as well, the thermal diffusivity
  involves thermal conductivity, specific heat and
  density.
• Characteristics
• Thermal diffusivity is always a function of
  temperature and is directional for anisotropic
  materials
• Thermal diffusivity may increase or decrease as a
  function of temperature, e.g.
• - graphite and many ceramics decrease with
  temperature
• - many metal alloys increase with temperature
• 3. Thermal diffusivity maybe dominated by the
  electronic or lattice contributions depending
  upon the type of material

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The System II
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The Instrument
Detector Furnace Laser / Xenon pulse source
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The Specifications

• Modular Design
• Different furnaces -125 up to 500C
• RT up to 500X
• RT up to 1250C
• RT up to 1600C
• Different pulse source Xenon or Laser pulse
  source (exchangeable)
• Different Sensors MCT detector (cryogenic
  application)
• InSb detector (standard)
• Sample robot round samples
• up to 6 samples 10 mm diameter
• up to 6 samples 12,7 mm diameter
• up to 3 samples 25,4 mm diameter
• square samples
• up to 6 samples 10x10 mm
• liquid samples
• Aluminum / Sapphire / Platinum

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XFA 500 Xenon Flash
Detector
Iris
Furnace
Sample Carrier
Xenon Flash
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LFA 1000 Laser Flash
Detector
Iris
Furnace
Sample Carrier
Laser
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Technical Specifications
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Sample Holders
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Sample Holders II
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Sample Holder For Liquids
Sample container Lid
Sample container Crucible
Liquid
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Sample Preparation
Graphite coating

• Samples are normally coated with a graphite film
  before testing.  The graphite serves several
  purposes.  When testing samples that do not
  naturally have a high value of emissivity or
  absorptivity, the graphite increases the energy
  absorbed on the laser side (bottom) and increases
  the temperature signal on the detector side (top)
  of the sample.  Also, a uniform graphite coating
  applied to both sample and reference material
  helps maintain similar absorptive and emissive
  efficiencies among samples, which is needed for
  accurate specific heat measurements.

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Application Areas
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Application Areas II
Silver, Copper, Silicon Carbide
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The Software
Software All thermo analytical devices of
LINSEIS are PC controlled, the individual
software modules exclusively run under Microsoft
Windows operating systems. The complete
software consists of 3 modules temperature
control, data acquisition and data evaluation.
The Linseis 32 bit software encounters all
essential features for measurement preparation,
execution and evaluation, just like with other
thermo analytical experiments. Due to our
specialists and application experts LINSEIS was
able to develop this easy understandable and
highly practical software.
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Applications
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TC vs. Sample Thickness
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TC vs. Temperature
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PTFE
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PTFE Applications

• Chemical processing and petrochemical sectors
  used for vessel linings, seals, spacers, gaskets,
  well-drilling parts and washers, since PTFE is
  chemically inert and resistant to corrosion
• Laboratory applications Tubing, piping,
  containers and vessels due to resistance to
  chemicals and the absence of contaminants
  attaching to the surface of PTFE products
• Electrical industry used as an insulator in the
  form of spacers, tubing and the like
• Virgin PTFE had been approved by the FDA for use
  in the pharmaceutical, beverage, food and
  cosmetics industries in the form of conveyor
  components, slides, guide rails, along with other
  parts used in ovens and other heated systems.
• Semiconductor sector used as an insulator in the
  production of discrete components such as
  capacitors and in the chip manufacturing process.
  

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Thermal Diffusivity
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Combined Result
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Ceramics
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Thermal Diffusivity
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Combined Results
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Inconel 600
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Thermal Diffusivity
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Thermal Conductivity
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Application Example Graphite (Polycrystalline)

• Graphite is an excellent material for checking
  the performance of a Laser/Xenon Flash Thermal
  Analyzer. The analyzed material shows a maximum
  thermal diffusivity around room temperature. The
  specific heat of the material which can be
  analyzed by comparative method or by using a DSC
  / High Temperature DSC shows a significant
  increase at higher temperatures.

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Application Graphite
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Application Example Aluminum Copper

• The pure metals Copper and Aluminum are used in
  this example to demonstrate the performance of
  the Linseis Laser Flash device. The measurement
  results of the two materials are compared with
  literature values. The measured results vary
  within 2 of the given literature values this
  demonstrates the excellent performance of the
  instrument.

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Application Aluminum Copper
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Application Example Isotropic Graphite (AIST)

• This graph shows the Thermal Diffusivity values
  measured on a Linseis LFA 1000 compared to the
  values measured at AIST Japan. The literature
  values of the used Isotropic Graphite from AIST
  the measured results on the LFA 1000 vary by less
  than 2. (National Institute of Advanced
  Industrial Science and Technology, Japan)

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Isotropic Graphite (AIST)
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The Best Method

• Best method for measuring Thermal Diffusivity
  ?Thermal Conductivity
• The flash method is the most accurate and
  fastest way of measuring the thermal diffusivity.
  It has bee estimated that world-wide over 80 of
  the thermal diffusivity measurements are
  conducted using the laser flash system

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Advantages of Flash Diffusivity Measurement

• Easy sample preparation because of simple
  geometry
• Sample sizes are typically 12,7 or 25,4 mm Ø or
  10mm square and range from 0.1 to 6 mm thick.
• 2. Less material is required because of small
  samples Some test methods used to measure
  thermal conductivity directly require very large
  samples i.e. 30cm x30cm x 5cm in some case
• Fast measurement time due to small samples
• With small samples steady state is reached
  quickly. Some thermal conductivity methods
  require days to complete a set of measurement.
• High accuracy
• Depending upon the material accuracies of /-
  3-4 or better can be usually achieved
• Wide thermal diffusivity / thermal conductivity
  range
• Thermal diffusivity 0.001 to 10 cm2/s
• Thermal conductivity 0.01 to 2000 W/m-K