Nanoindentation instruments are developed by employing very low indentation depths and loads. This standard is important for almost all instruments since they experience the problem of thermal drift to some extent.
The term 'thermal drift’ refers to the change in the displacement signal, while the normal force on the indenter remains constant and the material does not display mechanical properties, which are time dependent.
Thermal Drift Effect
Owing to thermal drift, the application of indentation instruments is quite limited for performing long-term measurements, like creep or grid indentation. Normally, two main techniques are used to reduce the effect of thermal drift.
One is to introduce a stabilization period prior to the measurement, and the other is to perform the indentation within a matter of seconds However, in both these approaches, the effect of thermal drift is reduced to some extent but not removed entirely. Hence, it is still difficult to conduct creep or long-term measurements, which can provide ambiguous results.
Ultra Nanoindentation Tester
Back in 1997, Anton Paar introduced the Nano Hardness Tester (NHT), which reduces the issue of thermal drift by using passive surface referencing. Continuous research and development at Anton Paar has resulted in the development of an advanced nanoindentation instrument called the Ultra Nanoindentation Tester (UNHT).
This device was developed using innovative materials and patented active surface referencing and takes a step forward towards a thermal drift free high resolution instrumented indentation. The special surface referencing principle combined with the use of next-generation materials and electronics nearly eliminates the issue of thermal drift and frame compliance.
Anton Paar has Compact and Open platforms on which the UNHT measurement head can be mounted easily. The system can be completed using other modules, like scratch testers, NHT, or Atomic Force Microscope. The UNHT can be utilized in displacement controlled mode or force controlled mode.
Figure 1. The UNHT on Anton Paar Open Platform modular system: 1 - UNHT head, 2 - NHT head, 3 - AFM, 4 - optical video microscope
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This information has been sourced, reviewed and adapted from materials provided by Anton Paar GmbH.
For more information on this source, please visit Anton Paar GmbH.