1. claims: 2-4, 15
Inventive concept I regards a method for chrome plating a substrate using an electrolyte solution, the method comprising: dissolving in an aqueous medium a trivalent chromium salt in an amount ranging from 0.1 mol to 0.9 mol per liter of the electrolyte solution; dissolving an oxalate compound in an amount ranging from 0.1 mol to 3.0 mol per liter of the electrolyte solution; dissolving a metal salt in an amount ranging from 0.1 mol to 4.0 mol per liter of the electrolyte solution, an alkali metal sulfate in an amount ranging from 0.1 mol to 2.0 mol per liter of the electrolyte solution, and an alkali metal halide in an amount ranging from 0.1 mol to 0.5 mol per liter of the electrolyte solution; and passing a current between a cathode and an anode through the electrolyte solution to deposit chromium on the substrate, wherein the step of dissolving the trivalent chromium salt comprises dissolving chromium (III) chloride and/or chromium (III) sulfate or wherein the step of dissolving the oxalate compound comprises dissolving sodium oxalate in an amount ranging from 0.1 mol to 1.0 mol per liter of the electrolyte solution, potassium oxalate in an amount ranging from 0.1 mol to 1.0 mol per liter of the electrolyte solution, and/or oxalic acid in an amount ranging from 0.1 mol to 3.0 mol per liter of the electrolyte solution and/or wherein dissolving the metal salt comprises dissolving aluminum sulfate in an amount ranging from 0.1 mol to 0.4 mol per liter of the electrolyte solution and/or aluminum chloride in an amount ranging from 0.1 mol to 4.0 mol per liter of the electrolyte solution; dissolving the alkali metal sulfate comprises dissolving sodium sulfate and/or potassium sulfate; and dissolving the alkali metal halide comprises dissolving sodium fluoride and/or potassium fluoride.1.1.2      Inventive concept I also concerns an electrolyte solution prepared in this way.

2. claims: 5, 6
Inventive concept II regards a method for chrome plating a substrate using an electrolyte solution, the method comprising: dissolving in an aqueous medium a trivalent chromium salt in an amount ranging from 0.1 mol to 0.9 mol per liter of the electrolyte solution; dissolving an oxalate compound in an amount ranging from 0.1 mol to 3.0 mol per liter of the electrolyte solution; dissolving a metal salt in an amount ranging from 0.1 mol to 4.0 mol per liter of the electrolyte solution, an alkali metal sulfate in an amount ranging from 0.1 mol to 2.0 mol per liter of the electrolyte solution, and an alkali metal halide in an amount ranging from 0.1 mol to 0.5 mol per liter of the electrolyte solution; and passing a current between a cathode and an anode through the electrolyte solution to deposit chromium on the substrate and wherein the dissolving the trivalent chromium salt, the oxalate compound, the metal salt, the alkali metal sulfate, and the alkali metal halide is performed in the following order: (1) dissolving the trivalent chromium salt and the oxalate compound; (2) dissolving the metal salt; (3) dissolving the alkali metal sulfate; and (4) dissolving the alkali metal halide and/or wherein the step of dissolving the oxalate compound comprises stirring the oxalate compound at a temperature ranging from 70 °C to 80 °C for a time ranging from 1 hour to 3 hours.

3. claims: 7, 10, 11
Inventive concept III regards a method for chrome plating a substrate using an electrolyte solution, the method comprising: dissolving in an aqueous medium a trivalent chromium salt in an amount ranging from 0.1 mol to 0.9 mol per liter of the electrolyte solution; dissolving an oxalate compound in an amount ranging from 0.1 mol to 3.0 mol per liter of the electrolyte solution; dissolving a metal salt in an amount ranging from 0.1 mol to 4.0 mol per liter of the electrolyte solution, an alkali metal sulfate in an amount ranging from 0.1 mol to 2.0 mol per liter of the electrolyte solution, and an alkali metal halide in an amount ranging from 0.1 mol to 0.5 mol per liter of the electrolyte solution; and passing a current between a cathode and an anode through the electrolyte solution to deposit chromium on the substrate, wherein the method further comprises adjusting the pH of the electrolyte solution to a pH ranging from 2 to 4 and/or maintaining the electrolyte solution at a pH ranging from 2 to 4 and/or maintaining the electrolyte solution at a temperature ranging from 30 °C to 40 °C during the step of passing the current, wherein the step of passing the current comprises applying a pulsed current or a direct current having a current density ranging from about 5 A/dm 2 to about 50 A/dm 2; and/orthe step of the passing the current comprises applying a pulsed current having a duty cycle ranging from about 20% to about 80%; and/or the step of passing the current is performed until a chromium layer having a thickness greater than 5 microns and hardness greater than 800 HV is formed on the substrate; and/orthe step of passing the current to deposit chromium on the substrate comprises passing the current to deposit chromium on a steel substrate, a copper substrate, a nickel substrate, a copper-coated substrate, or a nickel-coated substrate.

4. claims: 8, 9, 12, 14
Inventive concept IV regards a method for chrome plating a substrate using an electrolyte solution, the method comprising: dissolving in an aqueous medium a trivalent chromium salt in an amount ranging from 0.1 mol to 0.9 mol per liter of the electrolyte solution; dissolving an oxalate compound in an amount ranging from 0.1 mol to 3.0 mol per liter of the electrolyte solution; dissolving a metal salt in an amount ranging from 0.1 mol to 4.0 mol per liter of the electrolyte solution, an alkali metal sulfate in an amount ranging from 0.1 mol to 2.0 mol per liter of the electrolyte solution, and an alkali metal halide in an amount ranging from 0.1 mol to 0.5 mol per liter of the electrolyte solution; and passing a current between a cathode and an anode through the electrolyte solution to deposit chromium on the substrate, the method further comprising adding sodium lauryl sulfate and/or potassium lauryl sulfate in an amount ranging from 0.1 g to 1 g per liter of the electrolyte solution and/or adding sodium bromide and/or potassium bromide in an amount ranging from 0.1 g to 1 g per liter of the electrolyte solution and/or wherein the step of passing the current is performed using a carbonaceous anode, a platinum anode, or a platinized titanium anode, and wherein the trivalent chromium salt comprises chromium (III) sulfate and/or wherein: the step of passing the current is performed using a carbonaceous anode, and wherein the trivalent chromium salt comprises chromium (III) chloride.