Ultrathin diamond-like carbon coatings used for reduction of pole tip recession in magnetic tape heads

Diamond-like carbon (DLC) coatings were deposited using a commercial direct ion beam deposition technique on thin-film Al2O3-TiC inductive write heads . The coating thicknesses used were 5, 10, and 20 nm. Accelerated wear test s were conducted with metal particle tapes in a linear tape drive. Atomic f orce microscopy was used to image the thin-film regions to measure pole tip recession (PTR), relative wear of the pole tip with respect to the air bea ring surface. It is found that the coating wears off of the head substrate to a significant extent in the first 1000 km of sliding distance. The coati ng is worn off the substrate long before it wears off of the thin-film regi on. The existence of the coating on the thin-film region provides close eno ugh wear characteristics between the substrate and thin film that the two w ear at similar rates. This results in little growth in pole tip recession. Early in the wear test, the coated substrate wears at a slightly higher rat e than the DLC coated thin-film region due to the difference in tape contac t pressure between the two materials; decreasing PTR is the result. As the coating on the substrate wears significantly, PTR begins to increase with s liding distance. Failure does not actually occur until the coating has worn off of the thin-film region. Near failure, the coating delaminates locally . Results indicate that coatings of 20 nm thickness may provide protection against PTR in future tape drives. (C) 2000 American Institute of Physics. [S0021-8979(00)39808-5].