Analysis of Deposits from Friction at Head-Tape Interfaces by Raman Spectroscopy

To demonstrate the applicability of Raman spectroscopy to the analysis of thin heterogeneous deposits on surfaces, a sample of brown stain or friction polymer produced on sendust (85% Fe, 9% Si, 6% Al) surfaces of a simulated read/write head by a magnetic oxide tape making prior contact with a copper, aluminum or nickel surface was investigated. Raman spectra identified the base film of the tape as poly(ethylene terephthalate) or PET, and the magnetically active layers as containing mostly γ-Fe₂O₃. Conversely, Raman spectra of brown slain showed it to consist mainly of Fe₃O₄ and organic compounds. More brown stain was produced after copper contact than after aluminum contact, but only organic deposits were produced after nickel contact in these tests. It is speculated on the basis of these spectral data that the inhibiting effect of nickel could be the result of catalytically produced organic materials, which change the tribology on the head surface and inhibit the formation of brown slain or friction polymer.