Friction and Scratch of Multilayers

Multilayer coatings or hlms have been proven to be successful in various applications, especially for wear protection. In multilayer systems, the intrinsic stress can be effectively reduced by designing interface number and composite materials in terms of the application and process technique. Therefore, the multilayer technique by which a specihe functional composite is able to approach received more attention for many years [17,18]. Here we introduce the results on microscale friction and scratch of DLC/DLC and Fe-N/TiN multilayers. 

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A nano hardness tester (CSEM) with a Berkovich in-denter tip (diamond, radius 100 nm) was used. For all 

A nano scratch tester (CSEM) was employed to carry out the scratch test. A Rockwell diamond tip with a radius of 2 fim was used to draw at a constant speed 3 mm/min across the coating/substrate system under progressive loading of 130 mN maximum at a fixed rate 130 mN/min. The total length of the scratch scar is 3 mm. The critical load (L ) here is defined as the smallest load at which a recognizable failure occurs. The failure can be observed both by the built-in sensors and by the optical microscope. 

The same nano scratch tester was used to carry out the friction tests. The Rockwell diamond tip (radius 2 /u.m) was used to draw at a constant speed 3 mm/min across the sample surface under a constant load of 20 mN for which no scratches occurred for all the samples. Feedback circuitry in the tester ensures the applied load is kept constant over the sample surface. The sliding distance is 3 mm. The friction coefficient is defined normally as the ratio of the friction force and the applied load. 

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