Direct brazing of ceramics, graphite, and refractory metals

ORNL has been instrumental in the development of brazing filler metals for joining ceramics, graphite, and refractory metals for application at temperatures above 1000$sup 0$C. The philosophy and techniques employed in the development of these alloys are presented. A number of compositions are discussed that have been satisfactorily used to braze ceramics, graphite, and refractory metals without a prior surface treatment. One alloy, Ti--25 percent Cr--21 percent V, has wet and flowed on aluminum oxide and graphite. Further, it has been utilized in making brazes between different combinations of the three subject materials. The excellent flowability of this alloy and alloys from the Ti--Zr--Ge system is evidenced by the presence of filler metal in the minute pores of the graphite and ceramics. (auth)