Compositions: ceramic – Ceramic compositions – Refractory
Reexamination Certificate
2000-06-22
2001-10-09
Group, Karl (Department: 1755)
Compositions: ceramic
Ceramic compositions
Refractory
C501S098100, C501S098200, C501S098300
Reexamination Certificate
active
06300265
ABSTRACT:
TECHNICAL FIELD
This invention relates to structural suicides and more particularly to molybdenum-based suicides and eutectoid composites thereof.
BACKGROUND ART
Structural silicides have important high temperature applications in oxidizing and aggressive environments. There is a continuing and growing need for these materials for applications such as furnace heating elements, molten metal lances, industrial gas burners, aerospace turbine engine components, diesel engine glow plugs and materials for glass processing.
Some of the materials which would theoretically meet some of these needs are difficult to make and/or have deficiencies in engineering properties. For example, conventional &bgr;′-SiAlON is produced using silicon, aluminum nitride, and alumina in a nitrogen atmosphere. Due to impurities, &bgr;′-SiAlON is normally difficult to produce in a useful structural form according to such sources as the Encyclopedia of Materials Science and Engineering.
Therefore, it is an object of this invention to provide structural suicides with advantageous engineering properties.
It is another object of this invention to provide a method of making structural suicides with advantageous engineering properties.
It is a further object of this invention to provide molybdenum-based silicides.
It is yet another object of this invention to provide a method of making molybdenum-based silicides having improved purity.
It is an object of this invention to provide eutectoid composites of structural silicides having improved purity.
It is another object of this invention to provide a method of making eutectoid composites of structural silicides having improved purity.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. The claims appended hereto are intended to cover all changes and modifications within the spirit and scope thereof.
DISCLOSURE OF INVENTION
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, there has been invented a composition comprising &bgr;′-Si
6−z
Al
z
O
z
N
8−z
, wherein z=a number from greater man 0 to about 5, within a molybdenum disilicide matrix.
There has been invented a novel method for making structural disilicides comprising:
(a) combining a major portion of molybdenum disilicide with a minor portion of silicon nitride and a minor portion of aluminum in an inert atmosphere to form a mixture;
(b) forming the mixture into desired shape;
(c) sintering the shape to form a composite of &bgr;′-Si
6−z
Al
z
O
z
N
8−z
, wherein z=a number from greater than 0 to about 5, in a molybdenum disilicide matrix.
REFERENCES:
patent: 4814581 (1989-03-01), Nunogaki et al.
patent: 4983554 (1991-01-01), Hsieh
patent: 5063182 (1991-11-01), Petrovic et al.
patent: 5064789 (1991-11-01), Petrovic et al.
patent: 5085804 (1992-02-01), Washburn
patent: 5227199 (1993-07-01), Hazlebeck et al.
patent: 5296288 (1994-03-01), Kourtides et al.
patent: 5304778 (1994-04-01), Dasgupta et al.
patent: 5380179 (1995-01-01), Nishimura et al.
K. H. Jack, “Sialons,”Encyclopedia of Materials Science and Engineering, vol. 6, pp. 4385-4390, MIT Press, Cambridge, MA, 1986. No month.
K. Yamada and N. Kamiya, “High Temperature Mechanical Properties of Si3N4-MoSi2and Sl3N4-SiC Composites with Network Structures of Second Phases,” Proceedings of Engineering Foundation Conference on High Temperature Structural Silicides, May 25-29, 1998, Hyannis, Massachusetts.
Chen-Lung Fan and Mohamed N. Rahaman, “Factors Controlling the Sintering of Ceramic Particulate Composites: I, Conventional Processing,”Journal of the American Ceramics Society, 75[8](1992) pp. 2056-2065. No month.
L. Mouradoff, A. Lachau-Durand, J. Desmaison, J.C. Labbe, O. Grisot, R. Rezakhanlou, “Study of the Interaction between Liquid Aluminum and Silicon Nitride,”Journal of the European Ceramic Society, v. 13, (1994) pp. 323-328. No month.
F. Hong and M. H. Lewis, “Ceramic Matrix Composites via In-Situ Reaction Sintering,” Ceramic Science and Engineering Proceedings, 14[9/10](1993) pp. 699-706. No month.
E. C. M. Pennings and W. Grellner, “Precise Nondestructive Determination of the Density of Porous Ceramics,”Journal of the American Ceramics Society, 72[7](1989) pp. 1268-1270. No month.
John J. Petrovic, “High Temperature Structural Silicides,” paper presented at 21st Annual Cocoa Beach Conference and Exposition on Composites, Advanced Ceramics, Materials and Structures, Jan. 12-16, 1997.
Lars O. Nordberg and Thommy Edstrom, “Hot-Pressed MoSi2-Particulate-Reinforced Alpha-SiA1ON Composites,”Journal of the American Ceramic Society, 78[3](1995) pp. 797-800. No month.
Petrovic John J.
Rodriguez Robert P.
Bennett Gemma Morrison
Group Karl
Regents of the University of California
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