DEVELOPMENT OF THE COPPER-TIN DIFFUSION-BRAZING PROCESS

The copper-tin diffusion-brazing process has been studied with the obj ective of applying it to the joining of plasma-facing beryllium tiles to copper-based heat sinks in a nuclear-fusion reactor. The process is silver-free - an essential requirement for this application - and can be carried out at temperatures below 700 degrees C (1292 degrees F). This approach produces thin joints of essentially pure copper of high thermal conductance with the requisite strength. Satisfactory conditio ns for achieving robust joints under the constraints demanded by the n uclear-fusion application have been established. The roles of the proc ess parameters - thickness of the filler metal tin, the compressive lo ading applied to the components during the brazing cycle and the brazi ng temperature - have been assessed.