Method and operation of the Hot Disk transient plane source (TPS) technique for the measurement of thermal conductivity, thermal diffusivity and specific heat. The TPS technique can test solids, liquids, powders and pastes of varying shapes and sizes.

1. Hot Disk Transient Plane
Source (TPS) Technique
For Measurement of Thermal Conductivity, Thermal Diffusivity and
Specific Heat
Thermtest Inc.
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2. TPS 3500 Thermal Conductivity Instrument
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3. Hot Disk Transient Plane Source Technique
• Absolute method for the measurement of thermal conductivity and thermal
diffusivity, with calculation of specific heat and thermal effusivity
• No calibration required in order to make measurements
• No contact agent required between sensor and sample
• Thermal conductivity from 0.001 W/m•K up to 1800 W/m•K
• Temperatures from - 250 °C up to 1000 °C
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4. TPS Models
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TPS Model Thermal Conductivity
Range (W/m•K)
Temperature Range (°C)
Hot Disk TPS 3500 0.001 to 1800 -160 to 1000
Hot Disk TPS 2500 S 0.001 to 1000 -160 to 1000
Hot Disk TPS 2200 0.03 to 500 -160 to 750
Hot Disk TPS 1500 0.001 to 20 -160 to 1000
Hot Disk TPS 500 S 0.03 to 250 -160 to 300
Hot Disk TPS 500 0.03 to 100 -160 to 200
• Different models are available, depending on budget and
applications

5. TPS Testing Modules
• Different testing modules are available:
1. Standard: for measurement of bulk thermal conductivity and thermal
diffusivity of isotropic solids, liquids, pastes and powders
2. Anisotropic: for measurement of directionally-dependent (in-plane and
through-plane) thermal conductivity and thermal diffusivity
3. Slab: for thin, highly thermally conducting materials
4. Thin film: for measurement of coatings and stand-alone films
5. 1-Dimensional: for 1D measurement of elongated materials like rods
6. Specific Heat: direct measurement of specific heat
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6. TPS Sensors
• The TPS sensor is comprised of a planar 10 µm double nickel spiral covered on both sides by a
protective film (either Kapton, Mica or Teflon depending on the desired temperature and
application)
• Kapton: Up to 300 °C
• Mica: Up to 1000 °C
• Teflon: Acidic or corrosive environments
• Different radii sensors are available
• From left to right:
Kapton, Mica, Teflon
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7. Probing Depth
• The TPS theory assumes that
the sensor is in an infinite medium
of sample, and thus the probing
depth (penetration of heat)must
not exceed the boundaries of
the samples
• Thermal diffusivity of a material
will determine probing depth
during measurements
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8. Experimental Parameters
• An appropriate power output is chosen so as to raise the temperature of the
sample between 1 and 4 °C
• Highly thermally conductive materials will require higher power output than
thermally insulating materials
• A measurement time is chosen so as to allow the introduced heat to penetrate
some distance into the sample, but not reach the outer bounds of the sample
pieces
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9. Two-Sided Experimental Sample Setup
• The sensor is clamped in to the sample
holder
• The bottom sample piece is placed on
the adjustable plate, which is raised so
the bottom sample makes contact
with the sensor
• The top sample piece is placed on top
of the sensor and a light pressure is
applied to ensure good contact
between sensor and sample
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10. Single-Sided Experimental Sample Setup
• A single-sided sensor is also available for use
if two pieces of the same material cannot
be prepared
• A highly insulative, known backing material
is used underneath the sensor to prevent
heat loss to the surroundings
• The sensor is spring-loaded to help ensure
good contact between sensor and sample
and a weight is also placed on top of the
sample to improve contact
• The sensor can also be placed upside down
on a sample
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11. Hot Disk Software
• Experiment parameters are entered on the input screen:
- Sample Identity
- Available Probing Depth
- Sensor Type and Radius
- Measurement Temperature
- Measurement Time and
- Heating Power
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12. Hot Disk TPS Software
• Baseline temperature
drift is monitored before
the experiment and a
correction is applied if
needed
• Temperature increase vs.
time graph is plotted,
which thermal conductivity
is derived from
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13. Hot Disk TPS Software
• 200 data points are collected for each
transient measurement
• Some of these points near the start
will be eliminated to remove the effect
of contact resistance between the
sensor and sample
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14. Hot Disk TPS Software
• Slope is plotted from the T
increase vs. time graph,
which gives thermal
conductivity
• A residual plot is also
included, which compares
data to the curve fit,
providing extra confidence
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15. Hot Disk Software
• Results are calculated and shown for each experimental run
• Guiding warnings are provided for Total to Characteristic Time and Total Temperature Increase to ensure
optimized parameters are used. A yellow or red warning means that the parameter was slightly off
(yellow) or significantly off (red). Simple power and time adjustments can then be made.
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16. Conclusions
The hot disk transient plane source technique:
- Direct thermal property measurement, no complex calibration required
- Is multi-property: thermal conductivity, thermal diffusivity and specific heat
- Homogeneous and heterogeneous
- Isotropic and anisotropic
- Solids, liquids, pastes and powders
- No contact agent required
- Two-sided and single-sided sensors
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