Lubricant system for use in powder metallurgy
View Patent ↗The present invention is directed to metallurgical powder compositions having improved lubricant properties. These compositions of the invention include at least 90 wt. % of an iron-based metallurgical powder; a Group 1 or Group 2 metal stearate; a first wax having a melting range of between about 80 and 100° C.; a second wax having a melting range of between about 80 and 90° C.; zinc phosphate; boric acid; acetic acid; phosphoric acid; and a binder. Methods of compacting the compositions, as well as compacted articles prepared using those methods, are also described.
1. A metallurgical powder composition comprising:
at least 90 wt. % of an iron-based metallurgical powder;
a Group 1 metal stearate, a Group 2 metal stearate, or ethylene bisstearamide;
a first wax having a melting range of between about 80 and 100° C.;
about 0.03 wt. % to about 0.1 wt. % of a second wax having a melting range of between about 80 and 90° C.;
zinc phosphate;
boric acid;
acetic acid;
phosphoric acid; and
a binder.
2. The metallurgical powder composition of claim 1 comprising:
about 0.05 wt. % to about 1.5 wt. % of the Group 1 metal stearate, Group 2 metal stearate, or ethylene bisstearamide;
about 0.03 wt. % to about 0.1 wt. % of a first wax having a melting range of between about 80 and 100° C.;
about 0.03 wt. % to about 0.1 wt. % of a second wax having a melting range of between about 80 and 90° C.;
about 0.03 wt. % to about 0.1 wt. % of zinc phosphate;
about 0.03 wt. % to about 0.1 wt. % of boric acid;
about 0.03 wt. % to about 0.1 wt. % of acetic acid;
about 0.03 wt. % to about 0.1 wt. % of phosphoric acid; and
about 0.03 wt. % to about 0.1 wt. % of the binder.
3. The metallurgical powder composition of claim 1 , wherein the first wax is Montan wax.
4. The metallurgical powder composition of claim 1 , wherein the second wax is carnauba wax.
5. The metallurgical powder composition of claim 1 , comprising about 0.08 wt. % to about 1.2 wt. % of the Group 1 metal stearate, Group 2 metal stearate, or ethylene bisstearamide.
6. The metallurgical powder composition of claim 1 , comprising about 0.09 wt. % to about 1.1 wt. % of the Group 1 metal stearate, Group 2 metal stearate, or ethylene bisstearamide.
7. The metallurgical powder composition of claim 1 comprising ethylene bisstearamide.
8. The metallurgical powder composition of claim 1 , wherein the Group 1 metal stearate or Group 2 metal stearate is lithium stearate.
9. The metallurgical powder composition of claim 1 , comprising about 0.03 wt. % to about 0.07 wt. % of the first wax.
10. The metallurgical powder composition of claim 1 , comprising about 0.05 wt. % of the first wax.
11. The metallurgical powder composition of claim 1 , comprising about 0.03 wt. % to about 0.07 wt. % of the second wax.
12. The metallurgical powder composition of claim 1 , comprising about 0.05 wt. % of the second wax.
13. The metallurgical powder composition of claim 1 , comprising about 0.03 wt. % to about 0.07 wt. % of the zinc phosphate.
14. The metallurgical powder composition of claim 1 , comprising about 0.05 wt. % of the zinc phosphate.
15. The metallurgical powder composition of claim 1 , comprising about 0.03 wt. % to about 0.07 wt. % of the boric acid.
16. The metallurgical powder composition of claim 1 , comprising about 0.05 wt. % of the boric acid.
17. The metallurgical powder composition of claim 1 , comprising about 0.03 wt. % to about 0.07 wt. % of the acetic acid.
18. The metallurgical powder composition of claim 1 , comprising about 0.05 wt. % of the acetic acid.
19. The metallurgical powder composition of claim 1 , comprising about 0.03 wt. % to about 0.07 wt. % of the phosphoric acid.
20. The metallurgical powder composition of claim 1 , comprising about 0.05 wt. % of the phosphoric acid.
21. The metallurgical powder composition of claim 1 , comprising about 0.03 wt. % to about 0.07 wt. % of the binder.
22. The metallurgical powder composition of claim 1 , comprising about 0.05 wt. % of the binder.
23. The metallurgical powder composition of claim 1 wherein the binder is polyvinyl alcohol, cellulose ester, polyvinylpyrrolidone, or a combination thereof.
24. The metallurgical powder composition of claim 1 wherein the binder is polyvinyl alcohol.
25. The metallurgical powder composition of claim 1 wherein the binder is cellulose ester.
26. The metallurgical powder composition of claim 1 wherein the binder is polyvinylpyrrolidone.
27. The metallurgical powder composition of claim 1 , comprising:
about 0.1 wt. % of the Group 1 metal stearate, Group 2 metal stearate, or ethylene bisstearamide;
about 0.05 wt. % of the first wax;
about 0.05 wt. % of the second wax;
about 0.05 wt. % of zinc phosphate;
about 0.03 wt. % to about 0.1 wt. % of boric acid;
about 0.03 wt. % to about 0.1 wt. % of acetic acid;
about 0.03 wt. % to about 0.1 wt. % of phosphoric acid; and
about 0.03 wt. % to about 0.1 wt. % of the binder.
28. The metallurgical powder composition of claim 27 , wherein the Group 1 metal stearate or Group 2 metal stearate is lithium stearate.
29. The metallurgical powder composition of claim 27 comprising ethylene bisstearamide.
30. The metallurgical powder composition of claim 27 , wherein the first wax is Montan wax.
31. The metallurgical powder composition of claim 27 , wherein the second wax is carnauba wax.
32. The metallurgical powder composition of claim 27 , wherein the binder is polyvinyl alcohol, cellulose ester, polyvinylpyrrolidone, or a combination thereof.
33. A method of making a metal part comprising compacting the metallurgical powder composition of claim 1 .