Brazing fluxes consist of non-metallic materials, mostly salt mixtures of boron and halogen compounds (Table 4.2). Their purpose is to remove oxides from

the brazing surfaces and prevent their new build-up in order to allow a thorough wetting of these surfaces by the liquefied brazing alloy. Fluxes have to be activated already at a temperature below the working range of the brazing alloy. They are selected mainly according to the working temperature of the brazing alloy and the base material to be joined.