A development programme has been launched to develop a fast brazing technique to minimize the holding time at high temperature and consequently retain adequate mechanical properties of the CuCrZr alloy. This was achieved by induction brazing in Europe and by fast heating and cooling using an e-beam test facility in the Russian Federation.

Induction brazing tests were done using the only appropriate silver free braze alloy available in the market, the STEMET 1108 procured from the Russian Federation. It was found that this braze alloy had poor wetting properties and the quality of the product was variable. Difficulties were met for brazing Be tiles of dimensions representative of the Be tiles of first-wall panels. A few first-wall mock-ups were fabricated with inductively brazed Be tiles but showed thermal fatigue performance well below HIPped mock-ups, with detachment of Be tiles between 1.5 and 2 MWm~2.162,171 This result has been considered unsatisfactory. The development work on fast brazing equipment has been stopped in Europe and the effort is being concentrated on the development of a new silver — free braze alloy.

The fast brazing development in the Russian Federation has also been done using the STEMET 1108 alloy but fast heating was performed using an e-beam test facility. First-wall mock-ups were heated on the beryllium side by the e-beam and tempera­tures as high as 780 °C were achieved at the Be/CuCrZr joints for a very short time, followed by fast active cooling of the mock-ups, minimizing therefore the production ofbrittle intermetallic com — pounds.172 Good results were achieved on hyper — vapotron type mock-ups, developed at the early stage of the ITER design, for Be coated divertor

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components.