EFFECT OF TIO2 ADDITION OF OXIDIZING CATALYTIC ACTIVITY OF AN AL2O3 SLIDER FOR MAGNETIC DISKS

Oxidizing catalytic activity of a slider is a factor which could affec t wear of magnetic disks with a carbon overcoat. Al2O3 composites cont aining 2-50 mol% TiO2 were produced, which had different oxidizing cat alytic activities but nearly the same hardness and thermal conductivit y. Activation energy (Ec) for carbon oxidation when it is mixed with t he composite was measured to get the oxidizing catalytic activity, and it was found that Ec changed from about 70 kJ/mol for Al2O3 to about 110 kJ/mol for A/203 containing 9.1-16.7 mol% TiO2. TiO2 addition incr eased and decreased Ec. The former was due to segregation of the Ti-Al -O phase at the Al2O3 grain boundary, which could inhibit the catalysi s at the Al2O3 grain boundary. The latter was due to the unreacted TiO 2 phase, which by itself has high catalytic activity. TiO2-A/203 slide rs having different Ec were examined in sliding wear against a magneti c disk with a carbon overcoat using a pin-on-disk test system. It was found that wear rate of the carbon overcoat was lower when the slider had a larger Ec, i.e., lower catalytic activity. It was also found tha t wear particles of the carbon overcoat were likely to be larger with lower catalytic activity.