Adhesive bonding of beryllium

The effects of various adhesive and adherend variables on the tensile strength of stainless steel-beryllium-stainless steel assemblies have been determined. Epoxide, polyimide, urethane and cyanoacrylate adhesives were tested in conjunction with fully dense CIP HIP electrolytic grade, 95% dense hot pressed commercial purity and 90% dense plasma sprayed and sintered commercial purity beryllium (the latter tested parallel and perpendicular to the plasma spraying direction). Testing was done 14 days after bonding. The results demonstrate that all four adhesive types can show similar maximum strengths but that some show considerable scatter whilst in some cases difficulty in wetting the metal surfaces was encountered. All the types of beryllium studied show similar bond strengths and the plasma sprayed and sintered material does not exhibit any significant orientation effect. This latter material however does not bond well with cyanoacrylate adhesives. It is concluded that epoxide and urethane adhesive types are the most reliable for general purposes. An extension of the work to study ageing characteristics of the best adhesive-adherend systems is described. (author)