Corrosion and wear studies of uncoated and ultra-thin DLC coated magnetic tape-write heads and magnetic tapes

Abstract

Problems with corrosion and wear in magnetic tape drives lead the industry to consider the use of ultra-thin diamond-like carbon (DLC) coatings for tape heads and metallic tapes. In this study, corrosion and wear tests are conducted on uncoated and coated tape-write heads and tapes. A multi-component flowing mixed gas test, known as the Battelle Class II test, and an elevated temperature & humidity test are used to accelerate corrosion. While past researchers have evaluated corrosion effects by measurement of changes in magnetic properties of tape, surface analysis is successfully used here to study corrosion products directly. Corrosion specimens are examined using optical microscopy, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Functional drive tests are conducted to measure the effectiveness of DLC coatings, deposited by ion beam, via study of pole tip recession (PTR) in tape heads. Heads are shown to benefit in both corrosion resistance and in PTR resistance from the addition of DLC. In both cases, 20 nm thick coatings outperform 10 and 5 nm thick coatings. Coatings on ME tape show some limited benefit in corrosion resistance. ME tape specimens exposed in cartridges show much less evidence of corrosion than those exposed outside of cartridges. MP tape shows better corrosion resistance than uncoated and coated ME tapes.