Elevated Temperature Nanoindentation Testing - Nanoindentation Testing at Elevated Temperatures with the NanoTest - Micro Materials

 

Topics Covered

Nanoindentation Testing
Elevated Temperature Nanoindentation Testing with the NanoTest from Micro Materials
Key Applications for Elevated Temperature Nanoindentation Testing
Testing of Coatings
Testing of Automotive Components

Nanoindentation Testing

The use of nanomechanical test methods, such as nanoindentation, has been vital to the introduction of many advanced materials over the past 20 years. Now reliable hardness and modulus are possible on the thinnest coatings independent of substrate - and the technique has advanced to have its own ISO standard. However, despite these advances, a major drawback for many applications is that the nanoindentation instrumentation has been limited to operating at (or very close to) room temperature due to their extreme sensitivity to thermal effects. The materials of interest often operate at raised temperatures, so historically information about them has been inferred from results at ambient temperatures, which increases the scope for error.

Elevated Temperature Nanoindentation Testing with the NanoTest from Micro Materials

Designing instrumentation capable of reliable depth-sensing measurements at small scale and at elevated temperature presents a considerable technical challenge. Micro Materials Ltd (Wrexham, UK) have shown that reliable, high temperature, nano-scale depth-sensing measurements are possible up to ~750°C with their commercial nanoindentation instrument, the NanoTest(TM). The NanoTest(TM) is pendulum-based, with the sample mounted vertically so that indentation occurs horizontally. Horizontal loading is critical for elevated temperature measurements as the displacement measuring electronics are away from the ‘hot zone’. Also key is the use of separate heating of both indenter probe and test sample result in minimal heat flow (and thermal drift) occurring on indentation at elevated temperature. Early adopters of the technology include General Motors, MIT, Cranfield University and Cambridge University. As it becomes possible to accurately measure coating properties and performance at high temperatures product developments will speed up accordingly. No longer will the actual testing be an afterthought.

The NanoTest from Micro Materials.

Key Applications for Elevated Temperature Nanoindentation Testing

Testing of Coatings

Many applications are in coatings with environmental and energy conservation concerns driving many of the developments. In the automotive industry low-sulphur diesel fuels are required by the emission regulations. However, a side-effect of the sulphur removal process is that many naturally lubricous compounds are also removed. Additives are one solution but may not always be possible so manufacturers are turning to coatings for wear protection under tighter tolerances and higher contact pressures (e.g. DLC-coated injector pumps). The properties of such coatings at the engine operating temperature, such as hot hardness and stiffness, are critical to their performance and elevated temperature nanoindentation provides a convenient route to testing this.

Testing of Automotive Components

Weight saving is another important driver. For example, the valves in internal combustion engines are usually made of steel. Advanced applications require lower inertial mass and light non-ferrous alloys have been suggested for engine blocks. Despite the weight saving, these materials can exhibit poor tribological properties. Researchers at Birmingham University have begun to study how the mechanical and tribological properties of FeAl and TiAl intermetallics vary with temperature. Development of low friction and oxidation-resistant coatings for these lightweight materials is a natural progression. There are potential applications in gear development; gears could be made smaller and lighter if coatings could be developed to tolerate the resulting higher stresses.

As the mechanical properties of materials are greatly dependent on temperature, elevated temperature nanoindentation testing offered by Micro Materials provides a true picture of the expected operating performance of various components by replicating real life service conditions in the laboratory.

About Micro Materials

Established in 1988, Micro Materials Ltd are manufacturers of the innovative NanoTest system, which offers unique nanomechanical test capability to materials researchers for the characterisation and optimisation of thin films, coatings and bulk materials. The current model, the NanoTest Vantage was launched on June 1st 2011.

This information has been sourced, reviewed and adapted from materials provided by Micro Materials.

For more information on this source, please visit Micro Materials.

Source: Micro Materials Ltd.

For more information on this source, visit Micro Materials.

Date Added: Oct 30, 2008 | Updated: Apr 18, 2013
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