| 摘要 |
A composite metal coating for the protection or decoration of metal surfaces consists of alternate layers of Ni each 2.5-50m thick and of Co, Sn, Pd or an alloy of Co with up to 20% W or with up to 90% Ni each 0.25-7.5 m thick, the foundation and outermost layers both being of Ni and the total thickness of the coating being at least 6.25 m . Examples of Co alloys are Co-15% W, Co-46.7% Ni and Co-55.2% Ni. The layers may be formed by chemical deposition of Ni or Co as described in U.S.A. Specifications 2,532,283 and 2,532,284; by vacuum evaporation; by thermal decomposition of metal carbonyls; or by electrodeposition (see Group XXXVI). A final layer of Cr may be applied. Metal surfaces which may be coated include those of steel, Al, Cu, Zn and brass. |
