Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : March 07, 2022 - March 08, 2022
Heat-Assisted Magnetic Recording (HAMR) is expected as one of the future high density recording technologies. When lubricant film is heated in HAMR, degradation occurs by heating. Decomposed lubricant creates viscous stuff (smear) on head or magnetic disk surface. Smear can cause head crush. Degradation mechanism is studied from a view point of thermal, catalytic, and tribochemical reaction of Co, one component of CoPt alloy system in magnetic recording media. Two decomposition reactions of Z-Tetraol lubricant, i.e. perfluorinated polyether with 4 hydroxyl groups, are observed. Carbonization subsequent to oxidation occurs with increasing laser power. Temperature at critical laser power of carbonization decreases for Co(OH)2 < Co on laser heating in ascending order. Oxidation reaction is not observed in N2 environment. Decomposition of lubricant is observed on diamond-like carbon (DLC) film on CoPt film on hard disk media in laser heating and in sliding. As a result, the following mechanism is considered. Co(OH)2 is created on the disk surface following Co ion migration through DLC film and reacted with H2O. Co(OH)2 changes to Co oxides (CoO or Co3O4) which is known as active catalyst. Sliding accelerates the decomposition of lubricant by tribochemical reaction.
