Effects of SiO2 Contaminant on Thermo-Mechanical/Chemical Properties and Lubricity of PFPE Lubricants

Using the molecular dynamics (MD) simulations with ReaxFF potential, two different types of PFPE lubricants (Ztetraol and ZTMD) are prepared on a-C film, and SiO2 particles are adsorbed onto the lubricants at room temperature. From the simulation results, it is observed that the adsorbed SiO2 particles increase the stiffness of PFPE lubricants leading to less airshear displacement. Since Ztetraol has higher mobility with lower viscosity than ZTMD, the adsorbed SiO2 particles penetrate deeper into the Ztetraol lubricants. Accordingly, the effect of SiO2 on the airshear displacement is more obvious to Ztetraol than ZTMD. In addition, the adsorbed SiO2 particles increase the friction force and the amount of lubricant pick-up during the sliding contact with a nanosized a-C tip.

Behavior of Chemical Reaction Between Siloxane Compounds and Surface on Carbon Materials

Among many organic vapor contaminations released from structural components of hard disk drives, organic sioloxanes are particularly ominous, as they can be released in a relatively large quantity. Adherence of organic pollutants to the disk surface is a factor that hinders the normal operation of the head and the disk surface. It is known that volatile siloxane oligomers such as D4 (octamethyl cycletetrasiloxane) often form cyclic polydimethylsiloxane polymers in the presence of acidic catalysts. We investigated the reaction between D4 and some carbon materials such as diamond-like carbon in hard disk and graphite. The effect of the protection of carbon materials by Perfluoropolyether (PFPE) lubricants was observed.