Indentation hardness tests are used to measure the hardness of material against deformation. The indentation hardness of a material is loosely linked to its tensile strength, but as it is not a direct correlation, tests need to be performed to confirm the indentation hardness.
In traditional indentation methods, a tip usually made from a hard material like a diamond is pressed into a sample with unknown properties. The indentation is performed to a specific value, and either held on the sample or removed, depending on the application. The area of residual indentation is measured once this has been performed, and the hardness of the material is determined as the maximum load divided by the residual indentation area.
There are many different types of indentation hardness tests, and this blog post will outline nanoindentation hardness tests. Nanoindentation is the process of indentation on a material to test its mechanical properties in very small volumes.
Nanoindentation uses a different method to measure the indentation hardness, as traditional methods are limited to large materials. Small tip sized and loads are used, ensuring the measurement area is only a few square micro or nanometres.
For these tests, an indenter with a geometry that has a known high precision is used. The geometry of this indenter is used to determine the area of indent along with the known depth of penetration. The indenter tip is driven into the sample with an increasing load up to a specific value. During the process, the load and displacement are recorded. The values produced by a nanoindenter can be used to plot a load-displacement curve that can be used to extract a materials mechanical properties.
Young's modulus is one property that can be measured via nanoindentation. It is the measure of the stiffness of a solid material and defines the relationship between strain and stress. Creep properties can also be measured if a pause is applied once the indenter tip is at maximum load.
Other measurements are also achievable with a nanoindenter, including fatigue, the visco-elastic properties, and plastic-elastic deformation.
Nanoindentation is a versatile technique, as It can be used to determine the local properties of both heterogeneous and homogeneous materials. As smaller samples can now be measured, nanoindentation is widely adopted in materials where there is not enough space to perform microhardness testing. Typical applications include consumer goods, medical implants, and packaging.
Nanoindentation from Nanovea
Nanovea’s nanoindentation system complies with the following standards; ASTM E384, ASTM G171, ASTM E2546, ASTM B933, ASTM D4065, ISO 14577, DIN 50359. Our nanoindentation system can measure hardness, recovery depth, restoration ratio, fracture toughness, yield strength, and much more.
The nano module is designed to provide clients with ease of use, high accuracy, and longevity with a low maintenance cost. This is achieved with the unique combination of the ultra-sensitive load cell, piezo actuator, and large surface capacitor ring, which are all aligned vertically for maximum stiffness.
Unique measurements can be made in a true closed feedback loop as the nanoindenter directly measures the actual surface of the applied load. This feature enables quick reactions and fast events to be measured accurately, such as scratch and wear tests, or when fractures occur during indentation.
It is also straightforward to calibrate the ultra-sensitive load cell with a direct weight scale, ensuring fast calibration in less than 15 minutes for load, depth, and compliance.
If you would like any more information about Nanovea’s nanoindentation system, please get in touch.
This information has been sourced, reviewed and adapted from materials provided by Nanovea.
For more information on this source, please visit Nanovea.