engleski

From nanometric to meso-scale characterisation of friction using nanoindentation

Thin films are widely used as coatings in MEMS and NEMS as well as in precision devices, where they are often subjected to contact stresses and friction. Their frictional characteristics are hence of outmost importance. On the other hand, recently an original structured experimental methodology was developed and successfully implemented in determining the correlation between multiple process parameters and the resulting nanoscale friction, where an elaborated design of experiments approach is used, whereas the obtained measurements are analysed via advanced predictive machine learning algorithms. The same methodology is used in this work to characterise the meso-scale friction of an Al2O3 film, extending thus the value ranges of the most important influencing parameters beyond those achievable via scanning probe microscopy studies. A state-of-the-art nanoindentation device is hence used. The friction force is determined from nanoscratch experiments resulting from using the Berkovich tip in the range of scratch speeds from 2 μm/s to 50 µm/s and variable normal forces from 500 μN to 2 mN. The post-processing of the attained data allows obtaining a polynomial correlation function that can be used as an empirical model of thin films’ meso-scale friction.

Thin film friction ; experimental determination ; nanoindentation ; DoE ; meta-modelling

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