Hard iron plating of aluminum/aluminum alloys using sulfamate/sulfate solutions

A method of electroplating an iron layer from an iron anode onto aluminum-containing cathode in a ferrous electroplating solution, said iron layer having a microhardness of at least about 40 Rockwell C, said method comprising:

• (a) providing said ferrous electroplating solution, said solution comprising
• (1) ferrous iron having a concentration ranging from about 0.65 to 2.0 Moles of Fe.sup.2+ per liter of electroplating solution,
• (2) at least one anion selected from the group consisting of sulfamate and ammonium sulfate and associated with said Fe.sup.2+ ions,
• (3) a reducing agent in an amount sufficient to prevent oxidation of Fe.sup.2+ to Fe.sup.3+,
• (4) Cl.sup.- anion in an amount sufficient to promote dissolution of said iron anode, and
• (5) a wetting agent in an amount sufficient to prevent pitting of said aluminum cathode;
• (b) immersing said iron anode and said aluminum-containing cathode in said ferrous electroplating solution;
• and
• (c) conducting said electroplating of said iron at a current density ranging from about 35 to 110 Amp/ft.sup.2 for a time sufficient to plate a layer of iron on said aluminum-containing cathode to a thickness ranging from about 0.6 to 2 mils.

A ferrous electroplating solution for plating an aluminum cathode with iron in the presence of an iron anode comprising:

• (a) ferrous iron having a concentration ranging from about 0.65 to 2.0 Moles of Fe.sup.2+ per liter of electroplating solution;
• (b) an ammonium sulfate anion associated with said Fe.sup.2+ ions;
• (c) a reducing agent in an amount sufficient to prevent oxidation of Fe.sup.2+ to Fe.sup.3+, said reducing agent selected from the group consisting of ascorbic acid, hydrazine, and sodium hypophosphite;
• (d) Cl.sup.- anion in an amount sufficient to promote dissolution of said iron anode;
• and
• (e) polyethylene glycol in an amount sufficient to prevent pitting of said aluminum cathode.

A method of electroplating an iron layer from an iron anode onto an aluminum-containing cathode in a ferrous electroplating solution, said iron layer having a micro-hardness of at least about 40 Rockwell, C, said method comprising:

• (a) providing said ferrous electroplating solution, said solution comprising
• (1) ferrous iron having a concentration ranging from about 0.65 to 2.0 Moles of Fe.sup.2+ per liter of electroplating solution,
• (2) an ammonium sulfate anion associated with said Fe.sup.2+ ions,
• (3) a reducing agent in an amount sufficient to prevent oxidation of Fe.sup.2+ to Fe.sup.3+, said reducing agent selected from the group consisting of ascorbic acid, hydrazine, and sodium hypophosphite,
• (4) Cl.sup.- anion in an amount sufficient to promote dissolution of said iron anode, and
• (5) polyethylene glycol in an amount sufficient to prevent pitting of said aluminum cathode;
• (b) immersing said iron anode and said aluminum cathode in said ferrous electroplating solution;
• and
• (c) conducting said electroplating of said iron at a current density ranging from about 35 to 110 Amp-Ft.sup.2 for a time sufficient to plate a layer of iron on said aluminum cathode to a thickness ranging from about 0.6 to 2 mils.

A ferrous electroplating solution for plating an aluminum cathode with an iron layer in the presence of an iron anode, said iron layer having a micro-hardness of at least about 40 Rockwell C, said ferrous electroplating solution comprising:

• (a) ferrous iron having a concentration ranging from about 0.65 to 2.0 Moles of Fe.sup.2+ per liter of electroplating solution;
• (b) at least one anion selected from the group consisting of sulfamate and ammonium sulfate and associated with said Fe.sup.2+ ions;
• (c) a reducing agent in an amount sufficient to prevent oxidation of Fe.sup.2+ to Fe.sup.3+, said reducing agent consisting essentially of ascorbic acid, having a concentration within the range of about 1 to 30 g/L of electroplating solution;
• (d) Cl.sup.- anion in an amount sufficient to promote dissolution of said iron anode;
• and
• (e) a wetting solution in an amount sufficient to prevent pitting of said aluminum cathode.