Experimental The effect of temperature on filler metal erosion was studied using an automotive radiator core. In this case, joining progresses initially as expected. The cladding layer on the tube melts and flows by capillary action to the fin to tube joint and a normal fillet forms. However, as the peak brazing temperature is allowed […]
The European Association for Brazing and soldering — EABS for short — together with experts from Solvay Fluor, holds technical training seminars in which the theory and practice of flame and furnace aluminium brazing are communicated in detail. 40 interested participants from all over the world gather for the two day seminar in Hannover, Germany: […]
HF can potentially be formed during the flux brazing process. HF is very toxic, irritating to the eyes, skin and respiratory tract and cause severe burns of the skin and eyes. The threshold limit value (TLV) for HF is a ceiling concentration of 3 ppm (2.3 mg/m3), a concentration that should not be exceeded during […]
How to obtain? A lot of information can be gained from heat exchanger brazing cycle temperature profile. It is probably one of the most important pieces of information that the brazing engineer can use to fully understand his process. A temperature profile will provide information such as heating rate, maximum peak brazing temperature, time at […]
Furnace atmosphere The recommended furnace atmosphere conditions necessary for good brazing are as follows: Dew point: ≤ -40°C Oxygen: < 100 ppm Inert gas: nitrogen The most common source of nitrogen is that generated from liquid nitrogen storage tanks. A typical nitrogen gas specification from a liquid source indicates that the moisture content is <1.5 […]
As manufactured, a non-corrosvie K-Al-F-type flux typically is a mixture of potassium tetra-fluoroaluminate (KAlF4), and also contains potassium penta-fluoroaluminate (K2AlF5). K2AlF5 exists in different modifications: potassium penta-fluoroaluminate hydrate (K2AlF5 · H2O), and hydrate-free (K2AlF5). During the brazing process, the material undergoes essential physico-chemical alterations. While the chief component, KAlF4, is simply heated up, the compound […]
Process related causes The service life of a heat exchanger may be shortened due to corrosion caused by process related events. Some examples are listed below: Excessively high brazing temperature or too long time at temperature will lead to excessive Si diffusion in the core. Si diffuses along grain boundaries and this can increase the […]
In its simplest form, a slurry is held in a reservoir tank and continuously agitated to prevent settling. The slurry is pumped, usually with air-diaphragm pumps to the flux slurry cabinet where the heat exchangers moving on a conveyor are sprayed with the slurry. After spraying, the excess flux slurry is blown off in a […]
NOCOLOK® Sil Flux brazing is a technique, which eliminates the need for clad brazing sheet or conventional Al-Si filler metal. Sil flux brazing uses filler metal generated in-situ to effect brazing. The mechanism for creating this filler metal in-situ is described below: One of the surfaces to be joined is coated with a mixture of […]
The general appearance of NOCOLOK® brazed parts can range from relatively bright to light grey depending on the flux loading and furnace dew-point. When either is increased excessively over recommended levels, the appearance moves towards the grey colour. The flux residue usually can not be seen by the naked eye, however, it is visible under […]