Atmospheric effects of friction, friction noise and wear with silicon and diamond. Part I. Test methodology

This multi-part paper series gives evidence of tribothermally catalyzed, lu bricative interactions of low partial pressures of hydrogen, water vapor an d oxygen with silicon and polycrystalline diamond employed as bearing mater ials in moving mechanical assemblies (e.g., miniaturized rotors, bearings a nd gears) of microelectromechanical systems. In part I a test methodology i s described, whereby wide environmental range SEM-tribometric friction data are combined with friction noise analysis and applicable literature inform ation to further assist in interpreting atomic-level interactions governing the macroscopic friction and wear behavior of Si and diamond. To further c orrelate the wear- and thermal desorption-induced generation, re(de)constru ction and adsorbate-passivated annihilation of dangling sigma bonds with hi gh and low adhesion and friction, previously generated average coefficient of friction (COF) values are complemented with the concept of the associate d MAX.COF: the highest coefficient of kinetic friction gleaned from the raw computer-logged friction force data of each oscillatory cycle of an experi ment. The MAX.COF/COF ratios are used as measures of the friction noise as a function of temperature and atmospheric environment. These quantities, sa mpled at the appropriate data logging rate to circumvent test machine-relat ed vibrational disturbances, demonstrated signs of friction- and friction n oise-reducing gas-phase interactions of dry hydrogen with silicon (part II) and diamond (part III). Future installments will deal with similar lubrica tive properties of low partial pressures of wet hydrogen and dry oxygen.