Process for producing shaped refractory metal bodies

1. A method for fabricating an article comprising a tungsten heavy metal alloy or a molybdenum alloy, the method comprising:

mixing a metal powder with a first organic solvent and a dispersant to obtain a first mixture, the metal powder comprising a tungsten heavy metal alloy or a molybdenum alloy;

homogenizing the first mixture;

mixing the first mixture with a polymeric binder and a second organic solvent to form a second mixture;

homogenizing the second mixture;

casting a foil of the second mixture on a substrate;

drying the cast foil;

removing organic constituents of the second mixture from the foil; and

thereafter, sintering the foil to obtain a metal sheet comprising the tungsten heavy metal alloy or the molybdenum alloy.

2. The method of claim 1 , wherein forming the first mixture comprises mixing polymeric binder with the metal powder, the first organic solvent, and the dispersant.

3. The method of claim 1 , wherein forming the second mixture comprises mixing a plasticizer with the first mixture, the polymeric binder, and the second organic solvent, whereby the plasticizer reduces a glass transition temperature of the polymeric binder.

4. The method of claim 3 , wherein the plasticizer comprises benzyl phthalate.

5. The method of claim 1 , wherein the second organic solvent and the first organic solvent are the same.

6. The method of claim 1 , wherein the second organic solvent is different from the first organic solvent.

7. The method of claim 1 , wherein the second organic solvent and the first organic solvent form an azeotropic mixture in the second mixture.

8. The method of claim 1 , wherein before casting the second mixture has a solids content of about 30 percent by volume to about 60 percent by volume.

9. The method of claim 1 , wherein before casting a viscosity of the second mixture in the range from 1 Pa·s to 7 Pa·s.

10. The method of claim 1 , wherein casting the foil comprises (i) disposing the second mixture over the substrate, (ii) drawing the substrate beneath a first casting blade disposed over the substrate by a first height, and (iii) thereafter, drawing the substrate beneath a second casting blade disposed over the substrate by a second height less than the first height.

11. The method of claim 1 , further comprising bending the metal sheet to form a shaped article.

12. The method of claim 1 , wherein the dispersant comprises at least one of a polyester/polyamine condensation polymer, fish oil, or an alkyl phosphate compound.

13. The method of claim 1 , wherein drying the cast foil comprises drawing the substrate with the cast foil thereon through a drying tunnel, a drying temperature applied within the drying tunnel drying the cast foil.

14. The method of claim 13 , wherein the drying temperature is selected from the range of 25° C. to 70° C.

15. The method of claim 13 , further comprising flowing air countercurrently through the drying tunnel during drying of the cast foil.

16. The method of claim 1 , wherein (i) the foil is sintered at a sintering temperature, and (ii) the foil is disposed on a sintering substrate during sintering, the sintering substrate being unreactive with the tungsten heavy metal alloy or molybdenum alloy at the sintering temperature.

17. The method of claim 16 , wherein the sintering substrate comprises alumina, aluminum nitride, boron nitride, silicon carbide, or zirconium oxide.

18. The method of claim 1 , wherein a thickness of the metal sheet is less than 1.5 mm without rolling.

19. The method of claim 1 , wherein removing organic constituents of the second mixture from the foil comprises removing polymeric binder from the foil.

20. The method of claim 1 , wherein removing organic constituents of the second mixture from the foil comprises heating the foil at a temperature up to 600° under a pressure of 50-150 mbar.

21. The method of claim 1 , wherein removing organic constituents of the second mixture from the foil comprises flushing an atmosphere around the foil with a gas comprising nitrogen with 2% by volume or less of hydrogen.

22. The method of claim 3 , wherein removing organic constituents of the second mixture from the foil comprises removing plasticizer from the foil.

23. A method for fabricating an article comprising a tungsten heavy metal alloy or a molybdenum alloy, the method comprising:

mixing a metal powder with at least one organic solvent, a dispersant, and a polymeric binder to obtain a slip, the metal powder comprising a tungsten heavy metal alloy or a molybdenum alloy;

casting a foil of the slip on a substrate by (i) disposing the slip over the substrate, (ii) drawing the substrate beneath a first casting blade disposed over the substrate by a first height, and (iii) thereafter, drawing the substrate beneath a second casting blade disposed over the substrate by a second height less than the first height;

drying the cast foil; and

thereafter, sintering the foil to obtain a metal sheet comprising the tungsten heavy metal alloy or the molybdenum alloy.

24. The method of claim 23 , further comprising, before sintering the foil, removing organic constituents from the foil.

25. The method of claim 23 , wherein obtaining the slip comprises:

mixing the metal powder with a first organic solvent and the dispersant to obtain a first mixture;

homogenizing the first mixture;

mixing the first mixture with the polymeric binder and a second organic solvent to form a second mixture; and

homogenizing the second mixture.

26. The method of claim 23 , wherein drying the cast foil comprises drawing the substrate with the cast foil thereon through a drying tunnel, a drying temperature applied within the drying tunnel drying the cast foil.

27. The method of claim 26 , wherein the drying temperature is selected from the range of 25° C. to 70° C.

28. The method of claim 26 , further comprising flowing air countercurrently through the drying tunnel during drying of the cast foil.

29. The method of claim 24 , wherein removing organic constituents from the foil comprises removing polymeric binder from the foil.