Water Adsorption on Lubricated a-CHx in Humid Environments

Humidity influences the tribological performance of the head-disk interface in magnetic data storage devices. In this work a quartz crystal microbalance was used to measure the uptake of water on amorphous hydrogenated carbon (a-CHx) films at room temperature and pressures of water corresponding to relative humidities of ~25%: These experiments have used a-CHx films of varying thickness with and without lubricant. The lubricants used included Fomblin Z-03, Z-disoc, and Z-tetraol deposited on the surfaces of a-CHx films of various thickness. The amount of water adsorbed on the unlubricated a-CHx films is roughly independent of a-CHx film thickness. The presence of the lubricant reduces the amount of adsorbed water; however, the amount of water adsorbed in the presence of a lubricant does not depend significantly on the type of lubricant. These observations imply that water is adsorbed on the surfaces of the lubricant or the a-CHx film rather than being absorbed in their bulk.