DEVELOPMENT OF A NOVEL BRAZING MATERIAL TO JOIN CARBON-CARBON TO METALS

JOINING CARBON-CARBON (C-C) COMPOSITES TO METALLIC ALLOYS IS IMPORTANT FOR DOE'S FUSION ENERGY PROGRAM. USE OF CURRENT BRAZE ALLOY TECHNOLOGY PRODUCES JOINTS WITH UNBONDED AREAS DUE TO A LACK OF HOMOGENEITY OF TITANIUM IN THE ALLOY. THIS IS A RESULT OF INHERENT LIMITATION OF THE FABRICATION PROCESS. UNRELIABLE BRAZE JOINTS MADE WITH THE CURRENT GRAZE ALLOYS ARE NOT ACCEPTABLE FOR THE AGGRESSIVE CONDITIONS ENCOUNTERED IN THE PLASMA-FACING ENVIRONMENTS OF A FUSION REACTOR. AN INNOVATIVE APPROACH TO OVERCOME THIS PROBLEM OF ACTIVE METAL INHOMOGENEITY IN MAKING NOVEL BRAZE ALLOYS WILL BE USED. IN PHASE I OF THIS PROJECT THE OPTIMUM PROCESS PARAMETERS WILL BE ESTABLISHED AND UTILIZED TO FABRICATE STRIPS OF A NOVEL HOMOGENEOUS BRAZE ALLOY. ACTUAL BRAZE JOINTS BETWEEN C-C AND NIOBIUM-1% ZIRCONIUM ALLOY WILL BE MADE AND THE FEASIBILITY OF ACHIEVING FULLY-BONDED JOINTS IN TEST COUPONS THAT CAN WITHSTAND THERMAL SHOCK WILL BR DEMONSTRATED USING NON DESTRUCTIVE EVALUATION TECHNNIQUES, SUCH AS X-RAY MICROFOCUS AND LASER PULSE QUENCH METHODS. PHASE II EFFORTS WILL ADDRESS BONDING OF LARGER C-C TILES TO METALLIC ALLOYS TO CREATE FULLY DENSE AND STRONG JOINTS THAT CAN WITHSTAND THE AGGRESSIVE PERIODIC HIGH THERMAL FLUX ENVIRONMENTS OF A FUSION REACTOR.