1. A method for separating multi-wall carbon nanotubes from an aqueous slurry, comprising:
a) adding a water-immiscible organic solvent to an aqueous slurry comprising multi-wall carbon nanotubes;
b) isolating at least some of the multi-wall carbon nanotubes in the solvent; and
c) removing the solvent from the multi-wall carbon nanotubes to form dried multi-wall carbon nanotubes.
2. The method of claim 1 wherein the isolating forms spheroidal aggregates of multi-wall carbon nanotubes.
3. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates having diameters in the range of about 0.1 mm and about 5 mm.
4. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates having diameters in the range of about 0.5 mm and about 2 mm.
5. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates wherein the spheroidal aggregates comprise at least about 80 wt % multi-wall carbon nanotubes.
6. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates wherein the spheroidal aggregates comprise at least about 90 wt % multi-wall carbon nanotubes.
7. The method of claim 1 wherein the dried multi-wall carbon nanotubes are in the shape of spheroidal aggregates wherein the spheroidal aggregates comprise at least about 95 wt % multi-wall carbon nanotubes.
8. The method of claim 1 wherein the removing step is done by a procedure selected from the group consisting of evaporation, vacuum drying, convective drying and combinations thereof.
9. The method of claim 1 wherein the organic solvent comprises a solvent selected from the group consisting of hydrocarbons, oxygenated hydrocarbons, aliphatic solvents, aromatic solvents, alkanes, alkenes, alkynes, chlorinated hydrocarbons, chlorinated solvents, silicone oils, hydrocarbon oils, and combinations thereof.
10. The method of claim 1 wherein the organic solvent comprises hexane.
11. The method of claim 1 wherein the organic solvent comprises octane.
12. The method of claim 1 wherein the nanotubes and the solvent are present in a ratio from about 1 g nanotubes to about 0.1 ml solvent to about 1 g nanotubes to about 100 mls solvent.
13. The method of claim 1 wherein the nanotubes and the solvent are present in a ratio from about 1 g nanotubes to about 1 ml solvent to about 1 g nanotubes to about 25 mls solvent.
14. A method for forming spheroidal aggregates of multi-wall carbon nanotubes comprising:
a) adding a water-immiscible organic solvent to an aqueous slurry comprising multi-wall carbon nanotubes;
b) forming aggregates of multi-wall carbon nanotubes in the solvent; and
c) removing the solvent from the aggregates to form dried spheroidal aggregates of multi-wall carbon nanotubes.
15. The method of claim 14 wherein the dried spheroidal aggregates have a diameter in the range of about 0.1 mm and about 5 mm.
16. The method of claim 14 wherein the dried spheroidal aggregates have a diameter in the range of about 0.5 mm and about 2 mm.
17. The method of claim 14 wherein the solvent is removed by a procedure selected from the group consisting of evaporation, vacuum drying, convective drying and combinations thereof.
18. The method of claim 14 wherein the dried spheroidal aggregates contain at least about 80 wt % multi-wall carbon nanotubes.
19. The method of claim 14 wherein the dried spheroidal aggregates contain at least about 90 wt % multi-wall carbon nanotubes.
20. The method of claim 14 wherein the dried spheroidal aggregates contain at least about 95 wt % multi-wall carbon nanotubes.
21. The method of claim 14 wherein the organic solvent comprises a solvent selected from the group consisting of hydrocarbons, oxygenated hydrocarbons, aliphatic solvents, aromatic solvents, alkanes, alkenes, alkynes, chlorinated hydrocarbons, chlorinated solvents, silicone oils, hydrocarbon oils, and combinations thereof.
22. The method of claim 14 wherein the organic solvent comprises hexane.
23. The method of claim 14 wherein the organic solvent comprises octane.
24. The method of claim 14 wherein the nanotubes and the solvent are present in a ratio from about 1 g nanotubes to about 0.1 ml solvent to about 1 g nanotubes to about 100 mls solvent.
25. The method of claim 14 wherein the nanotubes and the solvent are present in a ratio from about 1 g nanotubes to about 1 ml solvent to about 1 g nanotubes to about 25 mls solvent.
26. An aggregate comprising multi-wall carbon nanotubes wherein the aggregate is spheroidal and has a diameter in a range of about 0.1 mm and about 5 mm, and wherein the aggregate contains at least about 80 wt % multi-wall carbon nanotubes.
27. The aggregate of claim 26 wherein the diameter is in the range of about 0.5 mm and about 2 mm.
28. The aggregate of claim 26 wherein the aggregate contains at least about 90 wt % multi-wall carbon nanotubes.
29. The aggregate of claim 26 wherein the aggregate contains at least about 95 wt % multi-wall carbon nanotubes.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A weldable, workable steel comprising, in combination:
a secondary hardened, stable, substantially mixed bainite and martensite phase steel having a BCC copper precipitated phase, M2C carbide strengthening precipitates where M is one or more elements selected from the group consisting of Cr, Mo, and V, and Ni-stabilized precipitated austenite for transformation toughening, said steel including in weight percent about:
0.030 to 0.06 carbon (C);
3.5 to 5.0 copper (Cu);
6.0 to 7.5 nickel (Ni);
1.6 to 2.0 chromium (Cr);
0.2 to 0.65 molybdenum (Mo);
0.05 to 0.20 vanadium (V); and
the balance Fe.
2. The steel of claim 1 characterized by a yield strength exceeding about 140 ksi.
3. The steel of claim 1 having a nominal composition in weight percent of about:
0.05\xb10.01 C;
3.65\xb10.05 Cu;
6.5\xb10.02 Ni;
1.84\xb10.05 Cr;
0.60\xb10.05 Mo;
0.10\xb10.01 V; and
the balance Fe.
4. A method for manufacture of a hardened steel alloy comprising the steps of:
(a) forming a melt into a casting comprised in weight percent of about 0.030 to 0.06 carbon (C), 3.5 to 5.0 copper (Cu), 6.0 to 7.5 nickel (Ni), 1.6 to 2.0 chromium (Cr), 0.2 to 0.65 molybdenum (Mo), 0.05 to 0.20 vanadium (V) and the balance iron;
(b) working and heat treating said alloy to form a substantially bainitic and martensitic microstructure;
(c) tempering said alloy at a temperature of about 500\xb0 C. to 575\xb0 C. for about 5 to 90 minutes to achieve precipitated austenite dispersed in the microstructure; and
(d) further tempering said alloy at a temperature of about 400\xb0 C. to 500\xb0 C. for about 1 to 10 hours to achieve M2C carbide particle formation wherein M is selected from the group consisting of Cr, Mo and V, said alloy including BCC Cu precipitated phase, Ni-stabilized precipitated austenite, and M2C carbides in a mixed bainite and martensite microstructure.