1. Hot Disk Transient Plane Source (TPS) Technique
For Measurement of Thermal Conductivity, Thermal Diffusivity and Specific Heat
Thermtest Inc.

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 W/m•K up to 1800 W/m•K
Temperatures from °C up to 1000 °C

4. Different models are available, depending on budget and applications
TPS Models
Different models are available, depending on budget and applications
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
Hot Disk TPS 2200
0.03 to 500
-160 to 750
Hot Disk TPS 1500
0.001 to 20
Hot Disk TPS 500 S
0.03 to 250
-160 to 300
Hot Disk TPS 500
0.03 to 100
-160 to 200

5. TPS Testing Modules Different testing modules are available:
Standard: for measurement of bulk thermal conductivity and thermal diffusivity of isotropic solids, liquids, pastes and powders
Anisotropic: for measurement of directionally-dependent (in-plane and through-plane) thermal conductivity and thermal diffusivity
Slab: for thin, highly thermally conducting materials
Thin film: for measurement of coatings and stand-alone films
1-Dimensional: for 1D measurement of elongated materials like rods
Specific Heat: direct measurement of specific heat

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

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

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

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

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

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

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

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

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

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.

16. The hot disk transient plane source technique:
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