Flying heads with sub-micron spacing for magnetic recording discs

This paper describes the analysis, design and development of flying heads for magnetic recording discs. In analysis the characterisctics of flying heads operating at sub-micron spacing, molecular mean free path (mmfp) effects must be taken into account. By applying the numerical calculation procedures to a modified Reynolds equation which considers slip-flow effects, the characteristics of air bearing load carrying capacity, stiffness and damping are clarified. In practical use of contact-start-stop type flying heads, the take-off characteristics have to be considered. The relations between the take-off speed and disc runout are discussed. These developments have enabled the production of flying heads with 0.2 μm and 0.36 μm spacings.     

Sorption of volatile compounds into electron beam irradiated EVA film in the vapour phase

In order to investigate the sorption of volatile compounds by electron beam irradiated ethylene/vinyl acetate copolymer (EVA) films, permeation measurements in the vapour phase were carried out. The diffusion coefficients of octane, ethyl hexanoate, octanal, octan-1-ol and d-limonene increased with an increase in the irradiation dose. The sorption of all volatile compounds in this study was depressed in electron beam irradiated film: the decreases in solubility coefficients for 20 Mrad EVA film were 15% for octane and ethyl hexanoate, 45% for octan-1-ol and octanal, and 50% for d-limonene. The enthalpy change in sorption (ΔH) of ethyl hexanoate was ?13·4 kJ mol^?1 for 50 g kg^?1 EVA film at a dose of 20 Mrad compared with ?27·6 kJ mol^?1 for the unirradiated one. In a homologous series of aliphatic alcohols, sorption was significantly depressed with increasing carbon chain length. Judging from both heat-seal strength and sorption behaviours, the most appropriate irradiation dose for the practical usage of irradiated EVA film was less than 15, 10 and 5 Mrad for 50, 95 and 150 g kg^?1 EVA film, respectively.