We have evaluated the effects of ultraviolet (UV) irradiation on spreading characteristics of three different kinds of PFPE lubricants (UV sensitive AM3001, polar Zdol200, and nonpolar Z03) coated over magnetic disks. This was accomplished by comparing the spreadings of irradiated and non-irradiated lubricant films around the step-shaped lubricant/disk boundary (step boundary flow), and by comparing the spreading over lubricant surface around the boundary between irradiated and non-irradiated lubricant films (UV-induced flow). We found that UV irradiation significantly affects the UV sensitive lubricant but hardly affects the nonpolar lubricant in term of the UV-induced flow, and it noticeably affects the nonpolar lubricant but hardly affects the polar lubricant in term of the step-boundary flow.
