EXOTHERMIC SPACE BONDING SYSTEM.
Final technical rept. 1 Jun 65-28 Feb 66,
WHITTAKER CORP SAN DIEGO CALIF NARMCO RESEARCH AND DEVELOPMENT DIV
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The report covers the development of a system, including materials, design, and techniques, for attaching adhesive pads to the exterior surface of spacecraft. The purpose of these pads is to provide attachment points for astronauts and their equipment while carrying out maintenance and repair functions in space. The pads consist of aluminum disks of 1-14 in. diameter and 0.050-in. thickness with a fastening stud on one surface and a layer of thermoplastic adhesive on the other surface. A thermal pulse to soften the adhesive and produce bonding under light pressure is obtained from the reaction of a small exotherm charge, which is enclosed in an insulative housing on the back or stud-side of the pad. Vacuum bonding experiments at approximately 0.000001 Torr plus the results of bond strength tests over the range from -100F to 250F are described. Adhesive bond strengths of nearly 900 psi at room temperature were obtained on aluminum skin specimens. Design strength objectives of more than 100 psi were achieved over the entire temperature range. Also described is the development and test of an exotherm heating unit for preheating spacecraft structure skins before pad bonding to improve adhesion and operational flexibility. Vacuum exposure tests on organic adhesive bonded specimens indicate suitability for extended use without degradation of adhesive strength. Author