Anand V. Lakshmikumaran

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 tests were conducted with metal particle tapes in a linear tape drive. Atomic force 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 bearing 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 coating is worn off the substrate long before it wears off of the thin-film region. The existence of the coating on the thin-film region provides close enough wear characteristics between the substrate and thin film that the two wear 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 rate than the DLC coated thin-film region due to...

Effect of Magnetic-Head Slot Orientation on Pole Tip Recession and Debris Generation in Linear Tape Drives

Pole tip recession (PTR) and debris generation lead to signal loss at the head-tape interface. Accelerated tape drive experiments and measurements of head-tape spacing were conducted using heads with different slot orientations. PTR was higher for blind-slotted (slots in the direction of tape travel) heads than for transverse-slotted (slots in the direction transverse to tape travel) heads. More tape debris was found on the surface of transverse-slotted heads, but most of this debris resided in the slots rather than on the bearing surface. The slots in the transverse-slotted heads act as tape cleaners, which accounts for the large debris buildup in the slots. This leaves fewer loose debris particles at the interface for the transverse-slotted heads. Little difference was found in the head-tape spacing for the two types at the conditions used in the drive experiments. It is proposed that the greater amount of loose debris available at the interface for use in three-body abrasive wear, which is believed to cause PTR, results in higher PTR in blind-slotted heads. Presented as a Society of Tribologists and Lubrication Engineers Paper at the ASME/STLE Tribology Conference in Seattle, Washington, October 1–4, 2000

Effect of slot edge defects on the head/tape spacing

The effect of slot edge defects on the performance of the head/tape interface is studied for single and double module heads. A number of typical edge defects was created artificially on a glass replica of an actual head, and three-wavelength interferometry was used to study spacing changes caused by these defects. The results show that head edge defects have a small influence on the flying behavior of tape with the effects being localized to the immediate defect area.