Posted in | Scratch Testers

Micro Materials CORE Range: Nano-Scratch

The CORE Nano-scratch system combines a wide force range with high measurement repeatability and accurate determination of critical loads and co-efficient of friction. It can handle both single pass scratch testing and multi pass wear testing.

The CORE Nano-scratch tester features are listed below:

  • High lateral rigidity for more reliable nano-scratch tests
  • High friction sensitivity
  • Wide load range (up to 500 mN) for single and multi-pass tests
  • Advanced software for yield stress measurement
  • Excellent thermal stability for nano-wear tests

The CORE Nano-scratch tester complies with all related standards for nano-scratch - ASTM 7187-10, ASTM 7027-05, and upcoming CEN standards.

Nano-scratch and nano-wear testing

Depth (baseline corrected) vs distance scratch test on a 60 nm ta-C film on Si wafer. Critical loads of failure can be determined from the depth profile and optical microscopy

The resistance to repetitive scratches can be a more useful predictor of abrasion resistance than single scratches. Figure shows increase in wear depth on sapphire (0001) with number of repeat scratches with a R = 5 micron diamond. The damage caused by 10 scratches at 100 mN was much greater than in single scratches to 500 mN.

Probe geometry for testing thin films

It is not suitable to measure adhesion of thin films with a conventional scratch test with a large (R = 200 µm) diamond indenter. Using a smaller radius indenter, the highest stress can be positioned at the interface of a thin-film system to enhance the sensitivity to differences in interfacial strength and examine any potential deficiencies in adhesion.

The Nano-scratch tester is provided with a R = 5 µm diamond indenter as standard. Different geometries are available on request.

Combining sensitivity and wide load range

The design of most low force instruments is limited for nano-scratch testing because of their low lateral rigidity. This results in the probe bending considerably when scratching samples with high/moderate surface roughness resulting in irregular scratch tracks and inaccurate friction measurements.

In contrast, the CORE nano-scratch offers a high lateral rigidity flexure design guaranteeing that sensitive friction sensors can be used and measurements can be carried out across the whole 500 mN load range.

Nano-scratch testing of ultra-thin ta-C coatings with a sharp spherical probe (R = 1 micron) shows differences in critical loads with film thickness. In this example the critical load was increased for the thicker film which delays the onset of phase transformation in the Silicon substrate.

Friction vs. load for TiN coatings and tool steel

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