スパッタ法による成形型用白金合金膜

概要

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Pt-Ir and Pt-Rh alloy films were deposited on a cemented carbide substrate by RF magnetron sputtering and film characteristics were examined to determined a candidate for the molds used for molding optical glass elements.XRD showed a highly oriented (111) texture for both the Pt-Ir and Pt-Rh films.Tensile stress existed in pure Pt films deposited in the present experiment. In Pt-Ir films, tensile stress decreased with increases in Ir content up to 20wt%. Film stress changed in sign from tension to compression, and the compressive stress increased with increases in Ir content. In Pt-Rh films, on the contrary, tensile stress increased only slightly with increases in Rh content up to approximately 40wt%.The Vickers hardness of the alloy films increased with increases in either Ir or Rh content, and this tendency is marked in the Pt-Ir alloy system Pt-80wt% Ir films shows a Vickers hardness of approximately 1200.Molds coated with pure Pt film or alloy films containing a small amount of Ir or Rh were degrated markedly by heat treatment at 600°C for 5hrs. Molds coated with Pt-Ir alloy films containing more than 30wt% of Ir, however, exhibited excellent performance despite heat treatment. No degradation was observed for molds coated with Pt-Ir alloy films containing more than 30wt% Ir.