Critical load for wear particle generation in carbon nitride coatings by single sliding against a spherical diamond

The 'critical load' for wear particle generation of carbon nitride coatings sliding against a spherical diamond under a linearly increasing load has b een examined in situ in relation to different nitrogen incorporation condit ions, i.e. assisted N ion acceleration energy and N ion beam current densit y, and different coating thickness. An environmental scanning electron micr oscope (E-SEM), in which a pin-on-disk tribotester was installed, has provi ded direct evidence in situ of when, how and where wear particle generation occurs during the sliding of carbon nitride coatings against a spherical d iamond. The in-situ examination of non-conductive carbon nitride coatings a re available in E-SEM free from surface charging with controllable relative humidity. The sliding tests under linearly increasing load up to 300 mN at a sliding speed of 10 mum/s have been carried out with the purpose of meas uring the 'critical load' for wear particle generation in a similar way to the traditional macro scratch testing. However, instead of the 'critical lo ad', the critical maximum Hertzian contact pressure P-max will also be used in the following for better understanding. Based on the systematic study o f seven combinations of nitrogen incorporation parameters and five kinds of thickness (0, 10, 50, 100 and 200 nm), the applicable range of P-max for w ear particle generation can be increased from 1.6Y to 1.83 similar to1.92Y or to 1.80 similar to1.89Y, where Y is defined as the yield strength of sil icon of 7 GPa, by coating carbon nitride onto silicon with changing nitroge n incorporation conditions of ion acceleration energy and ion current densi ty, or varing coating thickness from 10 to 200 nm. It also appears that the observed wear particle generation of carbon nitride coatings was associate d with a failure initiated in the silicon substrate rather than within the carbon nitride coating or at the coating-substrate interface in the light o f both the empirical identification and the theoretical discussion. (C) 200 1 Elsevier Science Ltd. All rights reserved.