Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
1999-02-25
2001-08-21
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S448000, C428S698000
Reexamination Certificate
active
06277493
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a joined ceramic product. More specifically, the invention is the joining of ceramics containing carbon by use of a bond agent having a metal carbide and silicon, and reacting the bond agent with the ceramics in a solid state displacement reaction.
BACKGROUND OF THE INVENTION
Displacement reactions are phase transitions wherein two or more elements or compounds in the solid phase react to form new product compounds that are more thermodynamically stable than the starting reactants. The formation of the stable product phases is accompanied by specific morphologies that can give the resultant composite desirable properties. Displacement reactions have been used for making composite materials as described in SYNTHESIS OF A MoSi
2
—SiC COMPOSITE IN SITU USING A SOLID STATE DISPLACEMENT REACTION, C H Henager, J L Brimhall, J P Hirth, Mat. Sci. and Engr. A155 (1992) 109-114, and for making a film product as discussed in U.S. Pat. No. 5,462,902, as well as in SYNTHESIS OF Ti
3
SiC
2
/SiC AND TiSi
2
/SiC COMPOSITES USING DISPLACEMENT REACTIONS IN THE Ti—Si—C SYSTEM, R. Radhakrishnan, C H Henager, Jr., J L Brimhall, S B Bhaduri, Scripta Metallurgica, Vol. 34, No. 12, pp. 1809-1814, 1996. However, displacement reactions have not been suggested for any other uses.
Joining of ceramics has been a problem for centuries. Metals can be welded and fastened together, but ceramics cannot be welded and the low fracture toughness of ceramics makes mechanical fastening difficult. The large differences in thermal expansion between metals and ceramics makes dissimilar materials joining a difficult problem, also. Presently, products using ceramics or that require ceramic/metal connections are generally designed to minimize the need to join ceramics. Accordingly, there is a need for a method to join ceramic parts and to join ceramics to metals.
SUMMARY OF THE INVENTION
According to the present invention, a joined product is at least two ceramic parts, specifically bi-element carbide parts with a bond joint therebetween, wherein the bond joint has a metal silicon phase. As used herein, the term ‘part’ refers to a macroscale 3-dimensional solid object, in any geometry, including but not limited to block, disc, rod, pipe, sphere, cone, and combinations thereof that has a microstructure of a plurality of micro-particulates or grains. As used herein, the term ‘bi-element carbide’ refers to compounds selected from the group including but not limited to MC, M
2
C, M
4
C and combinations thereof, where M is a first element and C is carbon. The metal silicon phase may be a metal silicon carbide ternary phase, or a metal silicide.
According to the method of the present invention, joining a first bi-element carbide part to a second bi-element carbide part, has the steps of:
(a) forming a bond agent containing a metal carbide and silicon;
(b) placing the bond agent between the first and second bi-element carbide parts as a pre-assembly; and
(c) pressing and heating the pre-assembly in a non-oxidizing atmosphere to a temperature effective to induce a displacement reaction creating a metal silicon phase interspersed with a silicon carbide phase bonding the first and second bi-element carbide parts.
It is an object of the present invention to provide a joined ceramic part.
It is a further object of the present invention to provide a method of joining ceramic parts.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements.
REFERENCES:
patent: 4925608 (1990-05-01), Rossi et al.
patent: 4961529 (1990-10-01), Gottselig et al.
patent: 5204294 (1993-04-01), Matsumoto
patent: 5462902 (1995-10-01), Henager, Jr. et al.
patent: 0 322 732 (1988-12-01), None
patent: WO 97/16394 (1997-05-01), None
Morozumi, S., et al., “Bonding mechanism between silicon carbide and thin foils of reactive metals,” J. Materials Science, 20 3976-3980, 1985.*
BH Rabin et al., “Joining of SiC-Based Ceramics by Reaction Bonding Methods”, pp. 195-201, 1993.
TJ Moore, “Feasibility Study of the Welding of SiC”, pp. 151-153, 1985.
Brimhall John L.
Henager, Jr. Charles H.
Battelle (Memorial Institute)
Jones Deborah
Young Bryant
Zimmerman Paul W.
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