Tribochemical Reactions on the Surfaces of Thin Film Magnetic Media

Abstract

An experimental study has been performed regarding the effect of extreme pressure (EP) additives on minimizing friction in order to achieve the required frictional properties of thin film magnetic media. I n shuttling motion, disuljide additives had no effect on friction, due to their inability to form a protective film. While alkyl phosphite changed the surface to phosphate film and reduced the coefJicient of friction, aryl phosphite was less effective because of the steric hindrance of the aromatic ring generated by hydrolysis. Together with the results of the enthalpy of preferential adsorption measurements, it was concluded that the effectiveness of alkyl phosphite as a n EP additive depended on the formation of a protective film on the rubbing surface and on the strength with which the lubricant anchored to the outermost phosphate surface. Based on these findings, a combination of alkyl phosphite and the ester lubricant exhibited further improved perfarmance for magnetic thin film media.KEYWORDS erally have the disadvantage of lower durability with regard to wear and friction because of their small thickness, approximately 0.2 pm, and smooth surface (2). A fundamental understanding of the tribology of magnetic head-media interfaces, especially of the lubricants, is crucial for the continued growth of the magnetic storage system. Thus, wear and friction issues should be resolved by the appropriate selection of lubricants.The purpose of this study was to reduce the friction of . . evaporated metal tape. The authors investigated the effect of the EP additives, which are blended into the lubricant on the evaporated metal tape with the aim of reducing friction. Some sulfur-and phosphorous-containing EP additives react with the rubbing surface and the newly-formed protective film contributes to the prevention of wear and reduction of friction (3)-(6). In this study, the mechanism of lubrication of EP additives on the evaporated metal tape is also discussed by surface analysis of the tapes and the static thermal reactions of the EP additives with cobaltous oxide.

Protic Ionic Liquids with Ammonium Salts as Lubricants for Magnetic Thin Film Media

“…The initial frictional coefficient is steady in the range of 0.3-1.4 g L -1 , and becomes higher for concentrations above 1.4 g L -1 . The stick-slip process was observed over the concentration of 1.4 g L -1 , but the friction coefficient significantly decreased and reached 0.18 after 20 reciprocating motions, which seems to indicate an excess of lubricant moved to the cylinder counter part [41]. At the lower concentrations (below 0.3 g L -1 ), the frictional coefficient increases with the increasing number of reciprocating motions, because the surface microstructures of the fine protrusion which is effective for friction reduction are scraped [35].…”

“…The tests were performed at 25°C and 60% relative humidity. The coefficient of friction between the tape and the cylinder was obtained using Euler's equation, i.e., friction coefficient = 2/p ln(T 1 /T 2 ) [36].…”