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AssigneeSumitomo Metal Industries, Ltd.
InventorsYasushi Hosoda, Masanari Kimoto, Shinya Hikino, Tsutomu Yoshida, Kiyoyuki Fukui
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A zinc or zinc alloy electroplated metal sheet comprises a metal sheet having, on at least one surface thereof, a composite zinc or zinc alloy plated coating formed by electroplating with zinc or a zinc alloy in a plating solution which contains at least one organic compound selected from the group consisting of alkynes, alkynols, amines and salts thereof, thio compounds, heterocyclic compounds, and aromatic carboxylic acids and salts thereof. The composite plated coating has a coating weight of 0.5-200 g/m.sup.2 and contains 0.001-10 wt % of co-deposited carbon. The electroplated metal sheet has improved post-painting corrosion resistance, press formability, and spot weldability.
A method for producing a composite zinc or zinc alloy electroplated metal sheet comprising subjecting a metal sheet to electroplating with zinc or a zinc alloy in a plating solution which contains at least one organic compound selected from the group consisting of alkynes, alkynols, amines and salts thereof, thio compounds, heterocyclic compounds, and aromatic carboxylic acids and salts thereof in an amount in the range of 0.001-10 wt % to form, on at least one surface of the metal sheet, a composite zinc or zinc alloy plated coating having a coating weight of 0.5-200 g/m.sup.2 and containing 0.001-10 wt % of co-deposited carbon, the composite zinc alloy plated coating having a carbon-rich surface layer wherein the carbon content is higher than the rest of the plating, the electroplating being performed by using a pulse current having an off-time of 1 msec to 1 second and a duty factor of at least 0.5 or a superimposed AC current having a frequency of 1-100 Hz and a current variation peak of .+-.1% to .+-.50%.
An electroplated metal plate which comprises a metal sheet having, on at least one surface thereof, a composite zinc or zinc alloy plated coating having a coating weight of 0.5-200 g/m.sup.2 and containing 0.001-10 wt % of co-deposited carbon and up to 10 wt % in total of one or more alloying metal elements, the composite zinc alloy plated coating having a carbon-rich surface layer wherein the carbon content is higher than the rest of the plating, and the .eta. phase present in the composite zinc alloy plated coating has an orientation index of not greater than 0.8 for the (00.multidot.2) plane and not less than 0.2 for the (10.multidot.1) plane.
A composite zinc alloy electroplated metal sheet comprising a metal sheet having, on at least one surface thereof, a composite zinc alloy plated coating having a coating weight of 0.5-200 g/m.sup.2 and containing 0.001-10 wt % of co-deposited carbon and including 0.4 to 2 % Co, wherein the composite zinc alloy plated coating has a carbon-rich surface layer with a thickness of 0.1-10 .mu.m, said thickness constituting from 5 % to 50% of the thickness of the plated coating, and the carbon-rich surface layer having a carbon content higher than the rest of the plating.
A composite zinc alloy electroplated metal sheet comprising a metal sheet having, on at least one surface thereof, a composite zinc alloy plated coating having a coating weight of 0.5-200 g/m.sup.2 and containing 0.001-10 wt % of co-deposited carbon and 0.2-10 wt % in total of one or more alloying metal elements, wherein the .eta. phase present in the composite zinc alloy plated coating has an orientation index of not greater than 0.8 for the (00.multidot.2) plane and not less than 0.2 for the (10.multidot.1) plane, and the carbon-rich surface layer having a carbon content higher than the rest of the plating.
Dependencies are inferred from the claim text.