Micro-tribology for advanced magnetic storage system

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In order to improve a tribological performance of the magnetic head/rigid disk interface operating under conditions of contact or near-contact recording, several studies were carried out. The obtained results may be summerized as follows :(1) A new type of protective carbon nitride (C-N) coating, 1.5-100 nm thick, was successfully synthesized by means of ion beam assisted deposition (IBAD) on both single-crystalline silicon and on the magnetic media of 1.8" magnetic rigid disk. Testing of tribological properties of the deposited C-N coating and their comparison with properties of the commercial carbon coating on the same magnetic media have shown, that :(a) friction coefficient in the range of 0.10-0.12 was observed for C-N coating sliding against silicon nitride pin. This friction coefficient was lower than that of carbon coating (about 0.3).(b) carbon nitride coating provided about five times longer life than carbon coating.(2) The effect of deposition parameters on such C-N coating … More properties as roughness, hardness, residual stress, tribological life, and the coefficient of friction was studied. It was found, that the residual stress has the strongest effect on the coating tribological life.(3) Two different ceramics such as SiC and Al203 were tested against a magnetic rigid disk coated with a commercial carbon coating. It was shown, that :(a) Silicon carbide slider provided much longer life of unlubricated disk than slider made of alumina. Grain detachment from alumina slider surface followed b severe abrasion of the carbon coating by formed sharp edges was found to be the main reason of short coating life.(b) Failure of carbon coating, sliding at low velocity against ceramic slider, occurred mainly bacause of mechanical wear. At a high velocity, however, a high friction-generated temperature was mostly responsible for the coating failure. A model and an empirical equaion were suggested to predict a maximum coating life at high sliding velocity using the calculated flash temperature value.(4) A method of the wear volume and the specific wear rate calculatin for the case when the whole wear process is localized in the surface asperities (a case of the textured magnetic rigid disk with a thin 1.5-35 nm protective ovsrcoat) was suggested. The method uses a bearing curves of the initial and worn surfaces to estimate the worn volume. This method was used for the evaluation of the specific wear rate of thin carbon and carbon nitride coatings on the magnetic rigid disk. The specific wear rate for the C-N coated disk was estimated to be about 10-5, which is about ten times smaller than that of commercial carbon coating of the same thickness. Less