Abstract
The present article describes the evolution of potassium bubbles during sintering of tungsten ingots pressed from doped powder. In the manufacture of incandescent lamp filaments, tungsten powder is produced by reduction of blue tungstic oxide which is doped with potassium disilicate and aluminum chloride. The reduced tungsten particles contain submicron pores. Analytical transmission electron microscopy (TEM) identifed two types of pores in reduced tungsten powder. First, there are pores which contain particles which consist of potassium, aluminum, and silicon, and second, there are pores which contain aluminum and silicon alone. On sintering at 2100 °C or 2300 °C, potassium aluminosilicate particles migrate together with grain boundaries to necks which form between tungsten particles. Sintering at 2100 °C or 2300 °C reduces the potassium, aluminum, and silicon concentrations of the particles. Atomic absorption spectroscopy (AAS) also measured reductions in the bulk potassium, aluminum, and silicon concentrations. In the present study, analytical TEM and Auger electron spectroscopy (AES) were used to describe the decomposition of dopant particles and the evolution of elemental potassium bubbles in sintered ingots.
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References
A. Pacz: U.S. Patent 1,410,499, 1922.
D.B. Snow:Metall. Trans., 1972, vol. 3, pp. 2553–54.
S. Leber, R.J. Arena, and D.L. Bly:Metals Handbook, 9th ed., 1984, vol. 7, pp. 629-32.
J.L. Walter, K.A. Lou, and M.R. Vukcevich: G.E. Report No. 89CRD061, General Electric Company, Schenectady, NY, Apr. 1989.
Ronald P. Simpson, George J. Dooley, and T.W. Haas:Metall. Trans., 1974, vol. 5, pp. 585–91.
D.J. Jones:Metall. Mater. Technol., 1973, vol. 5 (10), pp. 503–12.
D.M. Moon, R. Stickler, and A.L. Wolfe:Proc. 6th Int. Plansee Seminar, Metallwerk Plansee GMBH, Reutte, Austria, 1969 pp. 67–85.
H.G. Sell, D.F. Stein, R. Stickler, A. Joshi, and E. Berkey:J. Inst. Met., 1972, vol. 100, pp. 275–88.
G.A. Meerson, D.V. Kormilitsii, L.G. Abeleva, V.M. Amosov, and V.A. Liskovich:Inorg. Mater., 1966, vol. 2, pp. 514–18.
M. Menyhard:Proc. 10th Int. Plansee Seminar, Metallwerk Plansee GMBH, Reutte, Austria, 1981, pp. 31–41.
C.L. Briant and E.L. Hall:Metall. Trans. A, 1989, vol. 20A, pp. 1669–86.
A.W. Funkenbush, F. Bacon, and D. Lee:Metall. Trans. A., 1979, vol. 10A, pp. 1085–91.
A. Barna and J. Stark:Metall. Trans. A, 1978, vol. 9A, pp. 595–96.
M. Inaba, H. Kagami, and Y. Tuge:J. Mater. Sci. Lett., 1984, vol. 3, pp. 859–60.
B.P. Bewlay:Proc. 5th Int. Tungsten Symp., Budapest, Oct. 15–17, 1990, MPR Publishing Service Ltd., Shrewsbury, England, 1991, pp. 227–49.
H. Ortner and E. Lassner:Proc. 8th Int. Plansee Seminar, Metallwerk Plansee GMBH, Reutte, Austria, 1975, pp. 97–101.
L.R. Kehman, W.D. Wilkinson, and F.L. Yagga: Argonne National Laboratory Report No. ANL-4417, 1950.
V.L.K. Lou, T.E. Mitchell, and A.M. Heuer:J. Am. Ceram. Soc., 1985, vol. 68, pp. 49–58.
W.D. Clark:J. Inst. Met., 1940, vol. 66, pp. 271–85.
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Bewlay, B.P., Lewis, N. & Lou, K.A. Observations on the evolution of potassium bubbles in tungsten ingots during sintering. Metall Trans A 23, 121–133 (1992). https://doi.org/10.1007/BF02660859
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DOI: https://doi.org/10.1007/BF02660859