Microtribological studies of two-phase Al₂O₃-TiC ceramic at low contact pressure

The two-phase Al₂O₃-TiC ceramic (AlTiC) has many applications. One of the most common uses of AlTiC is for data recording heads where it is used as a bearing surface to support the magnetic sensing elements. This is one of the examples where the ceramic can be used in MEMS. Using Linear Tape Open (LTO) drive and metal particle (MP) tape media as the experimental platform; the wear of the AlTiC at very low loads and for very smooth surfaces has been studied. X-ray photoelectron spectroscopy (XPS), Auger electron Spectroscopy (AES) and Atomic Force Microscopy (AFM) were employed to analyse the AlTiC surface changes during wear at a variety of environmental conditions. Under all experimental conditions, the results showed the TiC phase of AlTiC to have been oxidized to form a surface layer. This gave rise to classical oxidational wear of that phase; with the delamination of the TiO₂ to form pullouts on the AlTiC surface and subsequent three-body abrasive wear particles were produced. The rate of oxidation of the TiC and hence the rate of production of the three-body wear particles increases with atmospheric water vapour content. In the experimental system chosen for this investigation, this results in an increase in differential wear, and hence pole tip recession of the magnetic metal poles of the recording heads. Pole tip recession was shown to correlate with increase in oxidation rate and also increase with atmospheric water vapour content. The wear of the Al₂O₃ phase was probably due to micro-adhesive wear with a wear rate much lower than that of the TiC phase.