The activation effect of Si on potassium fluoaluminate flux.

The main K3ALF6 and KALF4 co-crystallization of potassium fluoaluminate were also used as the coating agent and the agent.
Si in complex anion ACTS as an interfacial active agent.
This kind of interface activator also includes Ge and Ti, Zr, etc., which is a different kind of surfactant, which is different from cationic active agent (such as commonly used Zn, Cd, Tl, etc.).
However, it is similar to the process of the reduction and alloying of the parent material.
These new ecological elements are often highly active.
Since Si is common impurity in the reagent, and because the fluoride of compounds containing Si highly corrosive, often make the vessels (such as porcelain crucible, graphite with clay, etc.) of Si into the solder, and soldering flux of AI is to play the role of a stable Si.
According to our experiment content, 0.01% of Si is enough to form enough active layer on the mother material surface, and the high melting point potassium fluoaluminate can improve its activity greatly.
Therefore, the activation of Si is often overlooked.

In some fluoride brazing agents, AIF3 and KF are often added to improve the active agent, and it seems that the role of dissolution and stabilization of Si is also played.