Micro/nano-scale differential wear of multiphase materials: pole tip recession in magnetic-tape heads

Pole tip recession (PTR), which is caused by differences in wear resistance of the various phases in magnetic disk and tape heads, must be reduced because it is probably the main impediment to reduction of spacing. Here, a numerical model of PTR is presented. Experimental results suggest that three-body abrasion, which leads to primarily plastic wear, is the mode responsible for PTR. In the model, the authors assume this wear mode, and assume that wear is a function of load, sliding distance, hardness of the worn surface, and dimensionless wear coefficients. As sliding proceeds, PTR increases continuously, which leads to a continuous change in contact between three-body abrasives and poles; the load carried by the poles decreases as PTR increases. This is modeled by assuming that asperities of the head and medium deform and wear plastically to accommodate passage of particles through the interface. The pole wears less as PTR increases since the opening for sliding particles increases. This accounts for the decreasing rate of change of PTR with sliding distance found for disk and tape heads numerically and experimentally. For tape heads, the model predicts that each of the following leads to higher PTR: increasing the thickness of three-body particles, increasing tape tension, decreasing pole hardness, and increasing the pole wear coefficient.

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“…4 and were found using a commercial nanoindenter. 2,7,8 Other parameter values are also listed in the caption of Fig. 4.…”

Section: Modelmentioning

confidence: 99%

“…2 For tape drives that use metal particle ͑MP͒ tape, most of the abrasives are load-bearing and magnetic particles from the tape's magnetic layer. 8 In this study, a model of PTR is presented. Comparisons are made to experimental data; the effects of various parameters are also studied.…”

Section: Introductionmentioning

confidence: 99%

A model of pole tip recession growth in magnetic heads

Scott

Bhushan

2002

Journal of Applied Physics

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“…The substrate (of which the ABS is part) is made of Al 2 O 3 -TiC, the overcoat is made of Al 2 O 3 , and the pole is made of Co-Zr-Ta (CZT). Hardness measurements of these materials were made using a commercial nanoindentation instrument and were reported by Scott and Bhushan (2002). Reportedly, Al 2 O 3 -TiC has hardness of about 32 GPa, Al 2 O 3 has hardness of about 10 GPa, and CZT has hardness of about 8.5 GPa.…”

Section: Introductionmentioning

confidence: 99%

Measurement and mechanism of pole tip recession with advanced metal evaporated tape at low tension in a linear tape drive

Hansen

Bhushan

2005

Microsyst Technol

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Increased head-to-tape spacing in a magnetic tape drive causes signal loss. Pole tip recession (PTR) is a type of differential wear that occurs with tape heads and increases the effective head-to-tape spacing. The extent and mechanism of PTR that occurs when using metal particle (MP) tape has been examined by various authors and is well documented. To achieve higher recording density, tape manufacturers are developing thin-film tapes, such as advanced metal evaporated (AME) tape, for use in linear tape drives. The structure of AME tape is fundamentally different from MP tape and AME tape must be run at lower tension. The goals of this study are to determine the amount of PTR that occurs and to investigate the mechanism by which PTR proceeds when AME and MP tapes are rubbed against a commercial head in a linear tape drive at low tension. Atomic force microscopy (AFM) was used to measure PTR after interval sliding distances. It is shown that use of AME tape led to lower PTR than use of MP tape, and the probable mechanism of PTR growth is three-body abrasion, with different types of abrasive debris from the two tapes.

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