TAILIEUCHUNG - Recent Advances in Mechatronics - Ryszard Jabonski et al (Eds) Episode 2 Part 5

Tham khảo tài liệu 'recent advances in mechatronics - ryszard jabonski et al (eds) episode 2 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 544 . Chizhik Z. Rymuza Chikunov . Kuznetsova D. Jarzabek Rotation tribometry consists in rotational movement of a micro- or nanoindentor. The movement radius can be adjusted and decreased down to tens of nanometers. Here the area of the contact area-friction area overlapping on the sample approaches 100 . The analysis of the friction area is carried out by the SPM method The method enables one to study the phenomena of local change in a material as a result of tribochemical reactions on the contact spots. Friction of the silicon tip with a radius of 40 nm over the silicon surface was studied when the latter is protected by a monomolecular polymeric layer of thickness of 2 nm. A 100 cycles of tip sliding were performed with an external load whose value changes to several micronewtons. The rotation radius R of the tip relative to the chosen point on the sample was changed from several micrometers to 20 nm. The analysis of the friction zone by the SPM method showed substantial differences in the changes in the friction zone depending on the rotation radius of the indentor. For a greater rotation radius the abrasive wear of protective coating to a depth equal to the coating thickness is revealed. For small rotation radius beginning from 50 nm where the contact and friction areas are comparable a negative wear is seen Fig. 4 . an additional material arises on the friction area. An image of lateral forces shows high contrast Fig. 4d in the limits of the areas with a rotation radius of 50 nm which is indicative of a chemical change in the material. The thickness of the layer changed is about 4 nm Fig. 4b . These changes can be explained by the mechanochemical reaction of silicon oxidation that is due to high temperatures and shearing reactions in the friction zone. 2 2 Jt um Micro- and nanoscale testing of tribomechanical properties of surfaces 545 c Fig. 4. Rotation tribometry 3D image of the friction zone the left and right zones correspond to R 200 nm

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