Electrolyte solution and electropolishing methods

1. A method of micropolishing a surface of a non-ferrous metal workpiece, comprising:

immersing a surface of a non-ferrous metal workpiece in a bath of an aqueous electrolyte solution including a concentration of citric acid in the range of about 1.6 g/L to about 780 g/L and a concentration of ammonium bifluoride in the range of about 2 g/L to about 120 g/L and having no more than about 3.35 g/L of a strong acid;

controlling the temperature of the bath to be between the freezing point and the boiling point of the solution;

continuing the immersion of the surface in the bath until the finish of the surface is smoother than prior to immersion in the bath; and

removing the surface from the bath prior to causing a substantial change in the size or geometric shape of the workpiece.

2. The micropolishing method of claim 1 , wherein the temperature is controlled in the range of about 21° C. to about 85° C.

3. The micropolishing method of claim 1 , further comprising:

connecting the workpiece to an anodic electrode of a DC power supply and immersing a cathodic electrode of the DC power supply in the bath; and

applying a current across the bath.

4. The micropolishing method of claim 3 , wherein the application of current includes cycling the current on and off.

5. The micropolishing method of claim 4 , wherein applying current includes cycling between at least two different current densities.

6. The micropolishing method of claim 3 , wherein applying current includes providing current in a cyclical wave form.

7. The micropolishing method of claim 6 , wherein the cyclical waveform is varied in frequency during while applying current.

8. The micropolishing method of claim 3 , wherein the current is applied at less than or equal to about 255,000 amperes per square meter.

9. The micropolishing method of claim 8 , wherein the current is applied at less than or equal to about 5,000 amperes per square meter.

10. The micropolishing method of claim 9 , wherein the current is applied in the range of about 10.8 amperes per square meter to about 1076 amperes per square meter.

11. The micropolishing method of claim 3 , wherein the current is applied at a voltage of less than about 150 volts.

12. The micropolishing method of claim 3 , wherein the aqueous electrolyte solution includes a concentration of citric acid greater than or equal to about 600 g/L and a concentration of ammonium bifluoride in the range of about 10 g/L to about 120 g/L.

13. The micropolishing method of claim 12 , wherein the aqueous electrolyte solution includes a concentration of ammonium bifluoride in the range of about 10 g/L to about 20 g/L, and wherein the temperature is controlled to be greater than or equal to about 71° C.

14. The micropolishing method of claim 3 , wherein the aqueous electrolyte solution includes a concentration of citric acid less than or equal to about 300 g/L and a concentration of ammonium bifluoride in the range of about 10 g/L to about 120 g/L.

15. The micropolishing method of claim 3 ,

wherein the aqueous electrolyte solution includes a concentration of citric acid greater than or equal to about 600 g/L and a concentration of ammonium bifluoride less than or equal to about 20 g/L;

wherein the temperature of the bath is controlled to greater than or equal to about 54° C.; and

wherein the current is applied at a density greater than or equal to about 538 amperes per square meter and less than or equal to about 255,000 amperes per square meter.

16. A method of micropolishing a surface of a non-ferrous metal workpiece, comprising:

immersing a surface of a non-ferrous metal workpiece in a bath of an aqueous electrolyte solution including a concentration of citric acid greater than or equal to about 600 g/L and a concentration of ammonium bifluoride less than or equal to about 20 g/L, and having no more than about 3.35 g/L of a strong acid;

controlling the temperature of the bath to be greater than or equal to about 71° C.;

connecting the workpiece to the anode of a DC power supply and immersing a cathode of the DC power supply in the bath;

applying a current across the bath of greater than or equal to about 538 amperes per square meter and less than or equal to about 255,000 amperes per square meter;

continuing the immersion of the surface in the bath until the finish of the surface is smoother than prior to immersion in the bath; and

removing the surface from the bath prior to causing a substantial change in the size or geometric shape of the workpiece.

17. A method of micropolishing a surface of a non-ferrous metal workpiece, comprising:

immersing a surface of a non-ferrous metal workpiece in a bath of an aqueous electrolyte solution including a concentration of citric acid less than or equal to about 780 g/L and a concentration of ammonium bifluoride less than or equal to about 60 g/L, and having no more than about 3.35 g/L of a strong acid;

controlling the temperature of the bath to be less than or equal to about 85° C.;

connecting the workpiece to the anode of a DC power supply and immersing a cathode of the DC power supply in the bath;

applying a current across the bath of greater than or equal to about 538 amperes per square meter and less than or equal to about 255,000 amperes per square meter;

continuing the immersion of the surface in the bath until the finish of the surface is smoother than prior to immersion in the bath; and

removing the surface from the bath prior to causing a substantial change in the size or geometric shape of the workpiece.

18. The micropolishing method of claim 17 , wherein the bath temperature is controlled to less than or equal to about 54° C.; and wherein the applied current is less than or equal to about 5,000 amperes per square meter.

19. The micropolishing method of claim 17 , wherein the bath temperature is controlled to about 21° C. and the applied current is about 1076 amperes per square meter.

20. The micropolishing method of claim 17 , wherein the bath temperature is controlled to about 85° C. and the applied current is about 1076 amperes per square meter.

21. A method of substantially uniform controlled surface material removal on a non-ferrous metal workpiece, comprising:

immersing a surface of a non-ferrous metal workpiece in a bath of an aqueous electrolyte solution including a concentration of citric acid less than or equal to about 600 g/L and a concentration of ammonium bifluoride less than or equal to about 120 g/L, and having no more than about 3.35 g/L of a strong acid;

controlling the temperature of the bath to be greater than or equal to about 71° C.;

connecting the workpiece to the anode of a DC power supply and immersing a cathode of the DC power supply in the bath; and

applying a current across the bath;

continuing the immersion of the surface in the bath and application of current to achieve a uniform controlled amount of material removal from the surface; and

removing the surface from the bath following such controlled removal without causing a substantial change in the size or geometric shape of the workpiece.

22. The method of claim 21 , wherein the applied current is less than or equal to about 1076 amperes per square meter.

23. The method of claim 22 , wherein the applied current is less than or equal to about 53.8 amperes per square meter.