Chemical analyses of stains formed on Co - Nb - Zr metal-in-gap heads sliding against oxide and metal particle magnetic tapes

The playback efficiency of metal-in-gap (MIG) inductive read-write heads in magnetic recording devices is strongly influenced by wear of the air-bearing surface, metal core recession, and staining. In this study, stains were formed by sliding Co-Nb-Zr MIG tape heads against Co-³Fe₂O₃(oxide) and metal particle (MP) tapes in an accelerated mode. Optical and SEM imaging indicated that staining on a head run against the Co-³Fe₂O₃tape is thick and patchy, whereas on a head run against the MP tape, staining is in the form of a uniform film. Thickness variations of stains on the metal core formed by Co-³Fe₂O₃and MP tapes, measured using atomic force microscopy (AFM), were about 30-150 nm and 20 nm, respectively. Constituents of stains were analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning Auger electron spectroscopy (AES), and micro-Fourier transform infrared (micro-FTIR) and micro-Raman spectroscopies. Stains formed on the head run against the Co-³Fe₂O₃tape consist of organic species with trace amounts of iron and oxygen (inorganic) constituents. On the other hand, stains formed on the head run against the MP tape consist of inorganic constituents of oxidized magnetic particles from the tape. In addition to organic species and iron from tapes, stains formed by either tape also exhibit wear debris from the metal core, ferrite core, and glass region of the head itself. In the case of heads run against both tapes, most of the staining was found to be on the metal core.