The table below summarizes the material groups and their attributes.
Material group
Liquids & powders
Air
PDMS
Distilled Water
Foams
2704
2710
2720*
Polymers
CVPC
Lexan
HDPE
Pyrex*
Ceramics
Pyrex
Steatite
Pyroceram*
Alumina
Metals
Titanium
Stainless Steel
Sapphire
Phosphor Bronze*
Brass
Notes:
1. * means reference material for that group.
2. Low power, heater and guard 90 mA each.
3. High power, heater 105 mA and guard 125 mA.
4. All groups use start time 0.3s and stop time 0.8s.
9.3
Contact agent
The TCi sensor has a solid and hard surface. When measuring solids, there will always be some
contact resistance, which may significantly affect the results. The quality of heat transfer depends
on many parameters such as type of material, surface quality, etc.
To overcome this problem we use a contact agent (CA). The best CA available is water, since it
has relatively high thermal conductivity (~0.6 W/mK), low viscosity, and is easy to apply and
clean. Water can be used in a limited temperature range though, from ~5C to ~70C.
Calibrations of solids (except foams) are all done with water.
At temperatures lower than 5C and higher than 70C a different CA is needed. Any such
material will have a lower thermal conductivity than water. And since calibrations are done only at
room temperature with water (and automatically corrected at other temperatures), there is a need
to correct for the contact resistance. This correction factor (CF) may be constant over the entire
range of materials, or may have a simple relationship with regard to the measured 1/m.
Eff range
k range
2
Wm/k
Ws/m
K
0-1660
0-0.6
50-200
0.04-0.09
420-1450
0.13-1.2
1400-8000
1.1-29
4,500-19,000
6-120
TCi Operator Manual
Temp. range,
Power
C
level
Low
0T100
Low
0T 60
Low
-50T80
Low
-50T200
High
-50T200
Comments
No contact
agent
No contact
agent
99
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