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A ceramic-metal article including a ceramic rod, a metal rod, and a braze joining the ceramic and metal rods at a braze area of a coaxial bore in the metal rod. The bore gradually decreases in diameter, having an inward seat area sized for close sliding fit about the ceramic, a larger brazing area n

A ceramic-metal article including a ceramic rod, a metal rod, and a braze joining the ceramic and metal rods at a braze area of a coaxial bore in the metal rod. The bore gradually decreases in diameter, having an inward seat area sized for close sliding fit about the ceramic, a larger brazing area near the joint end, and a void area intermediate the braze and seat areas. The ceramic is seated without brazing in the bore seat area. The side wall between the brazing area and the metal outer surface is about 0.030-0.080 inch. The braze includes an inner braze layer, an outer braze layer, and an interlayer about 0.030-0.090 inch thick. A shoulder between the brazing and void areas supports the interlayer during bonding while preventing bonding between the void area and the ceramic member, leaving a void space between the void area and the ceramic member. A venting orifice extends generally radially through the metal member from the outer surface to the void space. The braze layers are palladium, platinum, gold, silver, copper, nickel, indium, chromium, molybdenum, niobium, iron, aluminum, or alloys thereof. Preferred is a gold-palladium-nickel brazing alloy. The interlayer is nickel, molybdenum, copper, tantalum, tungsten, niobium, aluminum, cobalt, iron, or an alloy thereof.

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A ceramic-metal article comprising: a generally cylindrical ceramic member having a joint end and a radially outward surface of a diameter D1; a generally cylindrical metal member having a joint end, a radially outward surface of a diameter D2, D2 being greater than D1, and a coaxial bore extending

A ceramic-metal article comprising: a generally cylindrical ceramic member having a joint end and a radially outward surface of a diameter D1; a generally cylindrical metal member having a joint end, a radially outward surface of a diameter D2, D2 being greater than D1, and a coaxial bore extending inwardly from said joint end, said coaxial bore having at least a brazing portion of an inside diameter D3, a void portion of an inside diameter D4, and a seat portion of an inside diameter D5; wherein said void portion is intermediate said braze portion and said seat portion, said ceramic member joint end is seated without brazing in said metal member bore seat portion, D5 is selected for a close sliding fit about D1, D3 is greater than D5, D4 is intermediate D3 and D5, and D2 is selected to result in a thickness D2-D3 of a bore side wall between said brazing portion of said bore and said outer surface, said wall thickness D0.030-0.080 inch; and a braze joining said ceramic member and said metal member bore braze portion, said braze comprising an inner braze layer, an outer braze layer, and an interlayer about 0.030-0.090 inch thick intermediate said inner and said outer braze layers, wherein said diameter D4 is selected to create an annular shoulder between said brazing bore portion and said void bore portion of a size to support said interlayer during said bonding step while substantially preventing bonding between said metal member void portion and said ceramic member by said braze, thus leaving an annular void space between said void portion and said ceramic member, a venting orifice extends generally radially through said metal member interconnecting said void space and said outer surface, said inner braze layer and said outer braze layer each comprise a braze material selected from the group consisting of palladium, platinum, gold, silver, copper, nickel, indium, chromium, molybdenum, niobium, iron, aluminum, and alloys thereof, and said interlayer comprises (a) a ductile metal or alloy or (b) a metal or alloy which has a low thermal expansion coefficient.