Why is There White Powder Flowing Out of the Heating Tube?

- Jun 22, 2020-

When brazing the heating plate, sometimes we will find that white or yellow powder flows out of the nozzle of the heating tube (see the figure below). What is this white powder?

Why is There White Powder Flowing Out of the Heating Tube


Some customers will also worry about whether there is a problem with the heating tube and whether the electrical performance will be affected?


The heating tube is filled with modified magnesium oxide (MgO). The magnesium oxide surface layer is coated with a layer of modifier silicone resin to prevent moisture absorption. During high-frequency welding or furnace welding, the silicone resin is partially decomposed and carbonized at high temperatures, which causes the mouth to be stained with white or yellow powder.


However, because the modified magnesium oxide is resistant to high temperatures above 850°C, the silicone resin is only partially decomposed and carbonized, so it does not affect the electrical performance of the heating tube. White or yellow powder can be removed by sandblasting to ensure the appearance quality.