The high lateral rigidity of the NanoTest™ Vantage™ system makes it particularly well suited to performing nano- and micro- scratch tests. In addition to simple ramped load scratches, multi-pass nano-scratch tests have been part of the NanoTest™ scratch module since 1991. The 3-scan procedure (topography scan – ramped load scratch - topography scan) described in CEN 17627 [1] enables identification of failure mechanisms, such as the role of stress, in more detail. With the 30 N head it is possible to perform micro-scratch tests to study thicker coatings and also investigate the influence of hardened sub-layers on scratch test critical loads and failure mechanisms. In addition to the standard repetitive scratch tests where all the scratches are in the same track, our novel randomised nano-scratch test technique involving statistically distributed parallel scratches has been developed to more closely simulate abrasion. 3-scan nano-scratch tests on 80 nm PVD ta-C coating on glass with a 3.8 µm probe. 1 = yield 2 = coating cracking 3 = total failure. The hard coating yields at low load despite having high H3/E2 due to plastic deformation of the much softer glass substrate. By removal of the instrument compliance contribution to the measured deformation the true nano-scratch and nano-wear depth data are displayed after levelling [2,3]. Ramped load micro-scratch test on 2 µm TiN PVD coating with high surface roughness on D2 tool steel. Test performed as 3-pass topography-scratch-topography test with a R = 25 µm radius spherical diamond indenter. 1 = critical load for chipping 2 = total coating failure Randomised (statistically-distributed) nano-scratch test Our novel randomised (statistically distributed) nano-scratch test technique has been developed to more closely simulate abrasion [4]. It’s a unique tool to help design more damage-tolerant materials. Wear development is monitored cycle-by-cycle to provide deeper understanding of failure mechanisms in coatings and bulk materials. The technique provides greater sensitivity to weak coating adhesion than a standard nano-scratch test – the figure shows obvious failure of an optical coating deposited on a non-clean substrate. References: 1. CEN/TS, 17629:2021 Nanotechnologies — Nano- and micro- scale scratch testing (2021). 2. BD Beake, VM Vishnyakov, R Valizadeh, JS Colligon, Influence of mechanical properties on the nanoscratch behaviour of hard nanocomposite TiN/Si3N4 coatings on Si, J Phys D: Appl Phys 39 (2006) 1392-1397. 3. BD Beake, AJ Harris, TW Liskiewicz, Review of recent progress in nanoscratch testing, Tribology 7 (2013) 87. 4. BD Beake, VM Vishnyakov, SR Goodes, AT Rahmati, Statistically distributed nano-scratch testing of AlFeMnNb, AlFeMnNi and TiN/Si3N4 thin films on silicon, J Vac Sci Technol A 42 (2024) 013104.
