Degradation study of lubricant with cyclotriphosphazene moiety under low-energy electron impact

When subjected to low-energy electron (<20 eV) impact, A20H lubricant was found to form ammonia or phosphoric acid droplets on the surface of the disk under appropriate temperature and humidity environment. The degradation mechanism was studied by time-of-flight mass spectroscopy and X-ray photoelectron spectroscopy. The side arm (O-C6H4-CF3) attached to cyclotriphosphazene moiety of A20H lubricant and the end group (CF2CH2OH) were found to be easily segregated at low electron dosage. PN core (CF2CH2OP3N3) breakdown occured at higher electron dosage. NH2/PO species which were formed from the PN core breakdown could be the most probable source of the corrosive droplets.