Laser Texture and Tribological Study of Alternative Substrates

Abstract

To achieve the highest recording density commercially available, alternative substrates with an average surface roughness (Ra) of 10–20 Å are generally used to meet the stringent head and disk separation requirement. A number of substrates are available for “next generation” products with average surface roughness in the 5 to 7 Å range. But, substrates with such ultra-smooth surface can seriously impair the tribological performance. Laser zone texture (LZT) provides a method to improve the tribology for future products. Commonly used with Al/NiP substrates, LZT decouples the CSS and data zones allowing for independent optimization of those zones. The authors have developed a tool for LZT of glass, glass-ceramic and ceramic substrates. In this paper, the authors evaluate three types of substrates (an alumino silicate, a lithium disilicate, and a modified alumina) for their ability to be laser textured and their tribology performance. Discussion will include the surface characteristics of the substrates, laser bump morphology, bump formation mechanism and the stiction behavior of these laser textured media. Finally, the authors will present results on initial stiction, CSS performance, environmental stress testing, acoustic emission testing and glide avalanche. Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 26–28, 1998