Traceable measurement of mechanical properties of nano-objects

Nano-objects, such as wires, sheets, cubes and tubes, have the potential to revolutionise the performance of materials and structures. However, their small scale means their behaviour is fundamentally different to that of bulk materials. Material testing techniques based on making indentations in material surfaces is commonplace for bulk materials but few nano-scale test methods are available. One based on atomic force microscopy can produce indentations but lacks the reliability needed to produce comparable results. Increasing the number of different material property measurement methods and ensuring comparability of results is key to reliable use of nano-objects in new products.

The EMRP project Traceable measurement of mechanical properties of nano-objects developed reference materials and used these to characterise nanoscale material testing methods increasing result reliability and comparability.

The Project:

• Developed and characterised reference nano-materials consisting of arrays of pillars, cantilevers and nano-particles for evaluating the performance of nano-material test methods.
• Improved a widely used method for the calibration of AFM cantilevers used in nano-material testing and achieved far lower measurement uncertainties for this type of calibration than previously possible.
• Developed a new method for determining the strength of nanowires based on scanning electron microscopy. This now forms the basis of a new measurement service enabling nano-object preparation and strength assessment inside a single instrument. 
• Developed computer simulation models for nano-indentation experiments and used these to predict how lattice dislocations and crystal orientation affects material deformation mechanisms.

An understanding of the properties of new materials provides the catalyst for their introduction into innovative applications and has the potential to provide cost effective solutions to existing or emerging technological challenges. This EMRP project improved the rigour with which nano-material properties can be determined. Atomic force microscopy (AFM) measurements can now comply with the ISO standard on instrumented indentation testing enabling this type of measurements to be readily compared with other nano and microscale test methods.

Comparing the performance of reference and test AFM probes is now possible using an easy to use micro device developed in the project, whilst a new calibration capability for certifying AFM probe performance is contributing to greater material testing reliability. This project has increased the methods available for the generation of the reliable nano-object material property required to support the integration of nano-objects into new products and technologies.