Fluid dynamic bearing spindle motors are now ubiquitous in magnetic recording disk drives. Areas of continuous improvement for these motor bearings are limiting oil oxidation and minimizing the motor voltage and electric charge buildup in the oil. This talk describes the development of an ester oil formulation with antioxidants and a kinetic model for synergistic formulation of primary and secondary antioxidants. A kinetic model that includes the synergistic effects of primary and secondary antioxidants and metal catalyst on oil oxidation lifetime is employed to guide the formulation. Modeling of the elementary chemical kinetic reactions provides a significant benefit because it reduces the development cycle time and lowers the total cost to obtain improved motor lifetime. Novel polyaromatic charge control additives have the potential to offer improved motor voltage stability as a charge conduction pathway parallel to the currently used aromatic amine antioxidants.

Formulation chemistry for ultra-stable ester-based oils

253rd National Meeting (2017)

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