Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Consolidation of powder prior to sintering
Reexamination Certificate
2006-04-05
2009-12-15
King, Roy (Department: 1793)
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Consolidation of powder prior to sintering
C264S625000
Reexamination Certificate
active
07632454
ABSTRACT:
The invention provides a method of forming a dense, shaped article, such as a crucible, formed of a refractory material, the method comprising the steps of placing a refractory material having a melting point of at least about 2900° C. in a mold configured to form the powder into an approximation of the desired shape. The mold containing the powder is treated at a temperature and pressure sufficient to form a shape-sustaining molded powder that conforms to the shape of the mold, wherein the treating step involves sintering or isostatic pressing. The shape-sustaining molded powder can be machined into the final desired shap and then sintered at a temperature and for a time sufficient to produce a dense, shaped article having a density of greater than about 90% and very low open porosity. Preferred refractory materials include tantalum carbide and niobium carbide.
REFERENCES:
patent: 3352951 (1967-11-01), Sara
patent: 4519966 (1985-05-01), Aldinger et al.
patent: 5139720 (1992-08-01), Takeda et al.
patent: 5368812 (1994-11-01), Calka et al.
patent: 5993545 (1999-11-01), Lupton et al.
patent: 6296956 (2001-10-01), Hunter
patent: 6719843 (2004-04-01), Schowalter et al.
patent: 2002/0013211 (2002-01-01), Takenami et al.
patent: 2002/0170490 (2002-11-01), Vodakov et al.
patent: 2005/0178315 (2005-08-01), Helava
patent: 2005/0223967 (2005-10-01), Schowalter et al.
patent: 1 184 541 (1959-07-01), None
patent: WO-2005/012602 (2005-02-01), None
Dalmau et al., “Crucible Selection in AlN Bulk Crystal Growth”,Mater. Res. Symp. Proc., 2004, pp. 1-5.
Schlesser et al., “Bulk Growth of AlN Single Crystals”,Abstract Book, International Workshop on Bulk Nitride Semiconductors III, Zakopanc, Poland, Sep. 4-9, 2004.
Schlesser et al., “Crucible materials for growth of aluminum nitride crystals”,Journal of Crystal Growth, 2005, pp. 75-80, vol. 281.
Kislyi et al., “Sintering Kinetics of Tantalum Carbide”, Powder Metallurgy and Metal Ceramics, 1982, pp. 765-767, vol. 21, No. 10.
Noveski et al., “Mass Transfer in AlN Crystal Growth at High Temperatures,”J. Cryst. Growth, 2004, vol. 264, pp. 369-378.
Noveski et al., “Seeded Growth of Bulk AlN Crystals and Grain Evolution in Polycrystalline AlN Boules,”J. Cryst. Growth, 2005, vol. 279, pp. 13-19.
Noveski et al., “Vapor Phase Transport of AlN in an RF Heated Reactor: Low and High Temperature Studies,”Mat. Res. Soc. Symp. Proc., 2004, vol. 798, pp. Y2.8.1 Y2.8.6.
Raghothamachar et al., “Synchrotron White Beam Topography Characterization of Physical Vapor Transport Grown AlN and Ammonothermal GaN,”J. Cryst. Growth, 2002, vol. 246, pp. 271-280.
Schlesser et al., “Growth of AlN Bulk Crystals from the Vapor Phase,”Mat. Res. Soc. Symp. Proc., 2002, vol. 693, pp. 19.4.1-19.4.6.
Schlesser et al., “Seeded Growth of AlN Bulk Single Crystals by Sublimation,”J. Cryst. Growth, 2002, vol. 241, pp. 416-420.
Sitar et al., “Growth of AlN Crystals by Vaporization of Al and Sublimation of AlN Powder,” IPAP Conference Series 4, Proceedings of 21stCentury COE Joint International Workshop on Bulk Nitrides, Jun. 15, 2004.
Strassburg et al., “The Growth and Optical Properties of Large, High-Quality AlN Single Crystals,”J. Appl. Phys., 2004, vol. 96(10), pp. 5870-5876.
Zhuang et al., “Grain Expansion and Subsequent Seeded Growth of AlN Single Crystals,”Mater. Res. Soc. Symp. Proc., 2005, vol. 831, pp. E11.1.1-E11.1.6.
Dalmau Rafael F.
Noveski Vladimir
Schlesser Raoul
Sitar Zlatko
Alston & Bird LLP
King Roy
North Carolina State University
Zhu Weiping
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