Level differences in hybrid heads after contact with various tapes

A level difference is formed between the metal and oxide in hybrid heads, such as metal-in-gap and sandwich heads, when used against tapes based on Fe pigment (MP) or on metal-evaporated tapes (MF). The level difference depends on a number of factors. Model experiments with soft metals show tape particles to be embedded. The length of metal layer and the type of head, metal-in-gap or sandwich, are important. A tape-substrate combination that produces a high substrate wear in general gives a low level difference. Nominally equal MP tapes, however, give different results. For amorphous metals, based on CoFeSiB, the level difference increases with relative humidity. Moreover, the level fluctuates in an irregular manner, presumably due to the flaking-off of oxide layers. A model of differential wear based on the wear equations for each component is given. The assumption that the local pressure exerted by the tape is a function of the level difference leads to a stationary value, but it is too large to be explained by the asperity distribution on the tape. Tape debris, made during contact with the head, provides an erosion mechanism for the level difference