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Scratch deformation response of thin CNx coatings at ultra-low loads

Lookup NU author(s): Professor Steve BullORCiD, Emeritus Professor Trevor Page


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The scratch test is often used for assessing the properties of coated systems since it readily allows the differing dominance of various deformation mechanisms - and the friction response - to be measured as a function of contact severity. Further, the scratch test can be used to determine a critical load at which failure of the coating-substrate interface occurs and thus give a semi-quantitative measure of the adhesion of the coating. Usually, micro- and macro-scratch tests are performed in the load range between 0.05 N to 100 N but here, to explore the response of a much thinner coating (300 nm of CNx on silicon), we report on scratches made with loads between 1 and 20 mN. We have found a load dependent transition in the scratch and friction responses. Below 4 mN, the scratches exhibited a completely elastic response with no evidence of failure. At 5 mN, the scratches showed some completely elastic areas and some areas that were typical of a buckle failure of the coating and at the same time, the coefficient of friction rose from approximately 0.1 to approximately 0.5. Above 5 mN, the scratches showed a continuous plastic groove and buckle-type failure. We discuss these results in relation to the scratch response and tribology of ultra-thin films.

Publication metadata

Author(s): Hainsworth SV, Bull SJ, Page TF

Publication type: Article

Publication status: Published

Journal: Materials Research Society Symposium Proceedings

Year: 1998

Volume: 522

Pages: 433-438

ISSN (print): 0272-9172

ISSN (electronic): 1946-4274

Publisher: Materials Research Society