Single and Double Reaction Layer Formation Using Reduced Active Element Containing Brazing Filler Metals

摘要

Active braze filler metals allow nonmetals to be joined to metals and nonmetals without the use of metallization coatings. This is accomplished by including sufficient active element to form a continuous reaction layer on each nonmetal surface resulting in strong, hermetic brazements. The reaction layer is made possible by the inclusion of small quantities, usually 1-3 weight percent, of a Group IVA metal into the braze filler metal composition. Because active filler metal compositions are limited and designed to work with various materials systems, the amount of active element is often more than required resulting in thick, brittle reaction layers or reactions with base materials that lead to excessive braze filler metal flow. Reduced quantities of the active elements titanium and zirconium have been added to standard braze filler metals to determine the quantities required to form continuous reaction layers without compromising tensile strength or promoting excess filler metal wetting/flow. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.