Platinum Metals Rev., 1993, 37, (3), 143
Platinum Foil in Ceramic Bonding
The solid state reaction that takes place between many ceramics and metals can be used to produce strong vacuum-tight joints which maintain their strength and durability even at elevated temperature, and the use of platinum foil for this purpose was reported here in 1981.
Reaction bonding to ceramics is best performed with platinum, which has a high melting point, is oxidation and corrosion resistant and therefore is the preferred metal for many bonding applications used in many hostile environments.
Now researchers at Lawrence Berkeley Laboratory, University of California, Berkeley, have developed a ceramic-ceramic joining method, partial transient liquid-phase bonding, that uses a thin foil of platinum to join copper coated alumina surfaces (M. L. Shalz, B. J. Dalgleish, A. P. Tomsia and A. M. Glaeser, “Ceramic Joining. Part I. Partial Transient Liquid-Phase Bonding of Alumina via Cu/Pt Interlayers”, J. Mater. Sci., 1993, 28, (6), 1673-1684).
High purity platinum foil was placed between two layers of alumina coated with thin layers of copper. Partial transient liquid-phase bonding was achieved through this copper/platinum interface at 1150°C, yielding a platinum-rich inter-layer and giving high-strength joints between platinum and alumina, at much lower temperatures than those required for conventional diffusion bonding. Flexure tests also showed that the obtained ceramic/metal interface strengths were higher than normally achieved for ceramics.