NOCOLOK® Cs is a special mixture that is intended for brazing Al alloys with a higher Mg content. By adding Mg to the alloy (types 6000 or 3000) higher material- and pressure resistance as well as better machine processing is now given, compared with NOCOLOK® standard Flux which could tolerate only low Mg contents.
During brazing, Mg diffuses to the Al surface and joins the flux. These chemical compositions have a higher melting point than the filler metal, so removal of the oxides by the flux is inhibited.
In this situation Cs can function as a buffer while the original potassium-based flux remains unchanged in its composition. So alloys with a Mg content of up to 0.8% can be brazed in a CAB furnace.
While flame brazing, the brazeability rate is even higher (1.5 % Mg) due to quicker heating.
The synthetic mixture of only 2% Cs represents an optimized ratio with respect to efficiency and profitability whereas the physical characteristics of NOCOLOK® standard grade such as melting point and granulometry remain nearly unchanged. The following benefits are also very interesting:
- Lower leakage rates and less porosity in production
- Better finish of the brazed work piece after brazing
- No change with respect to standard flux loading
- No change in brazing cycle.
The market trends are clearly obvious. Enormous global cost pressure requires reduction in costs for basic Al material (decrease in wall thickness) and lowering of production costs. NOCOLOK® Cs can help in this and make headers of heat exchangers or fittings more easily brazeable.