The principle and characteristics of the brazing flux of potassium fluoaluminate (potassium cryolite)

Brazing is a soldering technology that is used (or automatically generated in process) to be lower than the melting temperature of the parent material, and the operating temperature is lower than that of the solid phase line of the parent material and is higher than that of the solder liquid phase line.
Brazing solder melted when the parent metal to keep solid to liquid, liquid solder or the gap in the parent metal on the surface wetting, capillary flow, filling, spreading and interaction with the parent metal (dissolution, diffusion or intermetallic compound), cooling solidification form strong joint, which the parent metal together.
When soldering artifacts often whole heating, such as furnace brazing or soldering seam around the large area uniform heating, so the relative distortion of the workpiece and the braze welding head are much smaller than welding residual stress, easy to guarantee the precision of workpiece size.
The selection range of solder is wide. In order to prevent the change of the mother material organization and the characteristics, the solder with relatively low temperature of the liquid phase can be soldered.
As long as the solder, brazing and brazing method are chosen properly, the joint can be done without machining and can be "seamless".
In addition, as long as the brazing conditions are properly changed, there are also several brazing joints or continuous soldering.
The strength of the brazing can be strengthened by the brazing seam during brazing.
When the element of the solder has a certain degree of solid solubility with the parent material, the extension of the heat preservation time can cause the deep diffusion of some elements of the solder to the parent material and finally "disappear".
Brazing method lies in the weakness of solder and parent metal composition and properties of most cases can't be very close, sometimes far, with heavy metal solder brazing aluminium, for example, it is hard to avoid do not produce joint with the parent metal electrochemical corrosion of different level.

In addition, the choice of solder and the characteristics of the interface reaction there are certain limitations, most of the materials in soldering, brazing welding head and parent metal cannot achieve such as strength, increase the overlapping area can only be used to solve the problem.