Nanoindentation

Nanoindentation is a mechanical characterization technique used for assessing numerous nano- and micro-scale materials properties, including elastic modulus, hardness, adhesion and viscoelastic properties.

How it works – A small probe with a well-defined geometry is pushed into a sample’s sample surface with forces that range between 10s of nN to 10 N, and a load – depth curve is recorded during the indentation process. The resulting load – depth curve can be used to extract materials properties such as elastic modulus and hardness. Rate and dynamic properties can be estimated using various contact mechanics models.

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Instrumentation Available

Key Attributes

  • Large force range available for testing (max 10 N)
  • In addition to indentation, additional test modes are available including dynamic mechanical analysis (nano-DMA), scratch and wear testing, electrical contact resistance, and acoustic emission monitoring
  • Samples and resulting indents can be imaging using the SPM imaging mode

Strengths

  • Small sample volumes are probed, enabling testing of specific sample areas as well as thin films.
  • A wide range of samples, from biological and polymeric materials to diamond-like carbon films, can be tested reliably
  • Elastic modulus and hardness can be probed as a function of depth
  • In-situ SPM imaging allows for visualization of sample damage after indentation

Limitations

  • Tip calibration procedures are crucial for extracting reliable properties and can be time-consuming
  • Reliable measurements on rough surfaces are difficult to obtain
  • Built-in analysis algorithms assume linear, isotropic materials; crystallography and non-linear elastic behavior require more complex analysis

Applications

  • Measurement of elastic modulus and hardness as a function of depth
  • Fracture analysis
  • Scratch and wear testing
  • Thin film testing
  • Study of nanoindentation-induced phase transformations

Additional Reading