A Study of Thin Coating Wear in High Data Density Tape Heads

Abstract

Abstract This paper reports on an investigation of the wear of very thin (20–50 nm) Cr2O3 hard coatings, deposited on the linear tape open (LTO) data tape heads. The differential wear of the magnetic poles on the head and subsequent pole tip recession (PTR) leading to an increase in magnetic spacing is the major factor limiting the performance of high data density data tape heads. In order to reduce or eliminate PTR, very thin Cr2O3 hard coatings were employed to reduce PTR. The coatings were deposited on the LTO heads surface using unbalanced magnetron sputtering deposition techniques. Atomic force microscopy was used to analyze the surface topography of the coated head surface. Wear measurement was carried out by the means X-ray photoelectron spectroscopy and Auger electron spectroscopy combined with argon ion depth profiling. By these means, the very small reduction in coating thickness during the wear and hence the wear rate could be accurately determined. Wear tests were conducted in modified HP LTO Ultrium Generation 1 tape drives, and it is shown that wear rates of below 5.6×10−21m3/N⋅m could be measured. Nano indentation and scratch tests were employed to study the wear of the head materials and coated heads, which indicated that pole materials suffer the greatest wear under the same wear test conditions. The coatings on the pole areas have the lowest anti-abrasive wear resistance. Compared to the uncoated heads, the PTR of LTO heads were significant reduced by Cr2O3 coatings.