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High
Temperature NanoTesting
igh temperature nanohardness,
hot hardness, coatings, micromaterials, micro materials, nanotest,
nanoindentation, high temperature indentation, |
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Click here for
PDF information sheet
Click here for information on our 750°C hot stage
Since ALL MECHANICAL PROPERTIES ARE TEMPERATURE
DEPENDENT, the ability to perform NanoTest measurements at elevated
temperatures opens up significant new possibilities in surface and thin film
technology. The high temperature option which has been developed for the
NanoTest allows operation at temperatures up to 500°C.
Description of High Temperature Stage
- The displacement measurement capacitor has
been moved from its original position on the diamond holder to the bottom
of the pendulum.
- A thermal shield has been placed between
the pendulum and the stage.
- A tiny heater capable of maintaining 500°C
and a miniature thermocouple have been added to the diamond stub, close to
the tip itself. With both the diamond and sample at the same temperature,
heat flow between them does not occur upon contact, thus preventing
instantaneous dimensional changes due to thermal expansion.
- The hot stage itself consists of a
thermally insulating ceramic block which is attached to the NanoTest
sample holder. With the heater at 500°C, the increase in temperature
behind the ceramic block is typically less than 1°C. Temperature
controllers with automatic tuning are used for both the main hot stage and
the diamond heater.
- For reactive samples, the environmental
cabinet must be purged with an inert gas.
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High Temperature Measurement Procedure
- 1. The sample temperature and diamond
temperature are set as required and the system is left to reach thermal
equilibrium.
- 2. An automatic depth calibration is
performed at the operating temperature.
- 3. Prior to each test, the sample "hovers"
above the diamond. The hover time and distance are pre-programmed.
- 4. Sequences of indentation, creep,
scratch or impact tests are automatically performed in the normal manner.
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Gold was selected for
investigation since its small elastic recovery makes it an extreme case for
modulus determination. The sample was mechanically polished and mounted by
means of a zirconium silicate ceramic cement.
Indentations were performed at room temperature, 200 and 400°C using a
Berkovitch indenter. The following indentation parameters were used for all
measurements:
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It is
clear from the penetration depths read from the curves that significant
softening occurred at the higher temperatures. As shown in the table of
results, reductions in modulus also occurred as would be expected.
It is also interesting to note that at 400°C the curvature in the unloading
curve has disappeared. This curvature is indicative of elastic recovery
within the indentation itself.
Finally, in all cases creep occurred during the 60 s hold period at maximum
load. The amount of creep increased markedly with temperature as
anticipated. Investigation of thin film and surface creep is an important
application of high temperature NanoTesting. |
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Applications
Include...
- Microelectronics
thin film metallization/dielectrics adhesion variation with temperature
- Engineering
surface engineered engine components and bearings optimise mechanical
properties at the service temperature
- Pharmaceuticals
effect of processing temperature on composite properties and powder
adhesion
- Polymers
influence of temperature on complex modulus
- Wear-Resistant Coatings
scratch and impact behaviour at the service temperature coating
development and identification of operating limits
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