Clad-less Brazing

There are several suggestions for brazing technologies where the filler metal is generated during the brazing cycle from a coating layer on a plain aluminium sheet or on extrusion material. 

One method involves a mixture of flux with silicon powder, the NOCOLOK Sil Flux process [95]. At brazing temperature, the silicon powder diffuses into the aluminium substrate and generates Al-Si filler metal for joint formation. Sil flux can be applied with a binder to specific component surfaces, e.g. extruded tubes. In this case, the filler metal would be supplied from the tube and a clad fin sheet is not necessary. 

In Composite Deposition technology (CD process) [96], the filler metal for joint formation is derived from a composite powder, a compound consisting of potassium fluoroaluminate flux and Al-Si alloy. The CD powder is deposited selectively and accurately on heat-exchanger components prior to assembly and brazing. 

The common challenge for all cladless approaches is the development of a reliable coating procedure. 

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