High-temperature, high-pressure bonding of nested tubular metallic components

A graphite tool for use in the high-temperature, high-pressure bonding of a plurality of nested tubular metallic components to form a unitary tubular assembly thereof, said tool comprising:

• a tubular restraining member having an axis;
• a mechanically expandable tubular core mounted coaxially within said restraining member, said core being formed of a plurality of axially elongated, radially displaceable segments having curved outer faces which cooperatively define a cylindrical pressing surface which with said restraining member defines an annulus for accommodating said nested components, said segments having curved inner faces cooperatively defining two opposed and inwardly tapering axial bores which extend respectively from the ends of said core to the transverse midplane thereof;
• and
• solid, independently movable, tapered rams of circular cross section respectively fitted in said bores and movable inwardly therein to positions adjacent said midplane to contact most of the interior surface of said core and urge said segments radially outward to compress uniformly said nested components against said restraining member.

The method of bonding a metallic foil to a metallic substrate to form a unitary tubular assembly thereof, said method comprising:

• providing a bonding tool comprising a graphite tubular restraining member;
• a mechanically expandable graphite core coaxially mounted in said member, said core being formed of axially elongated and individually radially displaceable segments having curved outer faces which cooperatively define a cylindrical pressing surface which with said member defines an annulus, said segments having curved inner faces which cooperatively define two opposed and inwardly tapering axial bores;
• and independently movable, solid, tapered graphite rams respectively extending into said bores and movable inwardly therein to positions adjacent said midplane to urge said segments and pressing surface toward said member;
• positioning said foil and substrate in nested relation in said annulus, each of the members so positioned being in the form of a tube having a pair of abutting edges;
• maintaining the resulting loaded tool in a non-reactive atmosphere and at an elevated temperature promoting bonding of said foil and substrate;
• and
• while the loaded tool is so maintained, maintaining a selected inwardly directed force on each of said rams to exert radially directed force on most of the interior surface of said core and compress said foil and substrate against said restraining member to effect uniform bonding of the confronting faces of said foil and substrate.