Abstract: Improved bipolar plates comprising complex features can be manufactured for fuel cells in a simple, low cost manner by starting with an appropriate extruded piece. The complex features include one or more fluid ports which connect to channels internal to the bipolar plate. The method includes extruding a continuous sheet with appropriate linear channels on each surface of the sheet as well as within the sheet, transversely cutting the sheet, machining a fluid port or ports through the sheet to intersect with appropriate internal linear channels, machining at least two sealing ports through the sheet to intersect with the internal linear channels on opposite sides of the fluid ports, and applying sealant into the sealing ports in order to make appropriate seals to the internal linear channels.

Abstract: A method is provided for making a two-piece hollow airfoil having a complex geometry. Two metal sheets are formed into initial shapes so as to have a mean camber and twist. A series of raised ribs is machined onto the external side of each of the two sheets. The two sheets are joined together and sealed to form an in-process assembly. The assembly is subjected to high temperature and pressure to diffusion bond the sheets together at selected points. The assembly then subjected to internal pressure at high temperature in order to inflate and superplastically deform the assembly to the desired shape. Excess material is machined off after the inflation step.

Abstract: An improved method for superplastic forming diffusion bonding includes application of a protective encapsulating coating over the stop-off coating to prevent migration of yttria into regions to be diffusion bond.

Abstract: A method is provided for making a four-piece hollow airfoil. Four metal sheets are preformed into initial shapes. The sheets are sealed together into two pairs or sub-assemblies. Internal cavities are formed in one sheet from each pair prior to sealing. Each sub-assembly is subjected to high temperature and pressure in order to diffusion bond the sheets together at selected points. The cavities of each sub-assembly are then subjected to internal pressure in order to inflate and superplastically deform the sub-assemblies. The inflated sub-assemblies are combined to form a single assembly and the cavities are again subjected to internal pressure in order to bond the sub-assemblies together. The assembly is then exposed to hot isostatic pressing, after which, excess material is machined off.

Abstract: A method for making a three-piece hollow airfoil includes preforming three metal sheets into initial shapes and sealing them together to form an in-process assembly. Internal cavities are formed in the assembly prior to sealing. The assembly is subjected to high temperature and pressure to diffusion bond the sheets together at selected points. The cavities are then subjected to internal pressure at high temperature in order to inflate and superplastically deform the assembly to the desired shape. Excess material may be machined off after inflation.