A CRITICAL NATIONAL NEED EXISTS FOR RADICALLY IMPROVED MACHINABLE GLASS-TO-METAL JOINTS FOR NUCLEAR AND OTHER APPLICATIONS.

A CRITICAL NATIONAL NEED EXISTS FOR RADICALLY IMPROVED MACHINABLE GLASS-TO-METAL JOINTS FOR NUCLEAR AND OTHER APPLICATIONS. AT PRESENT, SUCH JOINTS ARE NOT AVAILABLE ON A RELIABLE, COST-EFFECTIVE BASIS. ADDITIONALLY, THEY ARE NOT SUFFICIENTLY STRONG OR REPRODUCIBLY VACUUM-TIGHT. THESEJOINTS ALSO DO NOT MEET THE REQUIREMENT FOR RESISTANCES TO THERMAL SHOCKS. IN THE PHASE I EFFORT, WE SHALL STUDY THE TECHNICAL MERIT AND FEASIBILITY OF OUR PROPOSED APPROACHES TO SOLVE THESE PROBLEMS BY: 1) MINIMIZING OR ELIMINATING ELEMENTAL SEGREGATIONS DUE TO GRAVITY TO ACHIEVE REPRODUCIBLY STRONG AND GENERALLY IMPROVED GLASS-TO-METAL JOINTS; 2) EXAMINING THE MAXIMUM OR CRITICAL TRANSIENT THERMAL STRESS PROFILES OVER THE JOINT REGIONS; AND 3) SPECIALLY GRADING THE ELEMENTAL COMPOSITIONS INSIDE THE JOINT REGION TO COMPENSATE THE MISMATCH STRESS PROFILES THROUGH TAILOR-GRADED THERMAL COEFFICIENTS SO AS TO ENSURE THAT THE MAXIMUM MISMATCH STRESSES WILL NOT EXCEED THE LOCAL MATERIAL STRENGTH AT ANY POINT AND TIME. CORRESPONDING TASKS WILL BE TO DEVELOP MEANS TO MINIMIZE THEGRAVITATIONAL SEGREGATION EFFECTS, TO DETERMINE THE CRITICAL TRANSIET MISMATCH PROFILES, AND TO STUDY WASY FOR DESIGNING SPECIALLY TAILORED, GRADED SEALS.