Sputtered ZrO/sub 2/ overcoat with superior corrosion protection and mechanical performance in thin film rigid disk application

A sputtered zirconia overcoat for thin-film rigid-disk applications has been developed with exceptional corrosion protection and mechanical performance. The target material is a transformation-toughened yttria-stabilized zirconia with yttria composition in the range between 5 and 15 wt.%. At thickness between 20 and 30 nm, the film provides excellent wear resistance and low friction coefficient even after repeated contact start-stop testing, and it offers much greater corrosion protection than the conventional carbon overcoat of comparable thickness. A transmission electron microscopy analysis of the sputtered film shows that it is composed of polycrystalline particles, with grain size of the order of 10 nm. The microstructure and the mechanical characteristics of the sputtered film can be modified by the addition of up to 15 wt.% alumina to the target. The grain size of the film can be reduced by the alumina addition, so that extremely fine-grained to near-amorphous structure can be obtained. The friction coefficient is reduced further with alumina addition, and corrosion protection is increased.<
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