Care este cauza filmului vrac când profilul de aluminiu este negru la temperatura camerei? Cum să facem acest lucru?

The reason:
1 If the degreasing and cleaning are not thorough, the black film formed after blackening will fall off if it is wiped gently;
2 activation is not good;
3 Timpul de întunecare este prea lung;
4 este mic, conținutul soluției este ridicat, iar conținutul de nitrit este ridicat;
5 solution acidity is high; &n aluminum alloy building profile insulation profile bsp;
6 înlocuitor de cupru este rapid, aditivi insuficienți;
7 oil immersion time is short.

1 Strengthen pre-treatment, pay attention to degreasing and cleaning;
2 After degreasing, the parts must be fully activated, not only to neutralize the residual lye on the surface, but also to activate the metal surface and increase the bonding strength between the film and the substrate;
3 reduce the blackening time,
4 to strictly dilute the formulation solution according to the formulation requirements;
5 can be neutralized with NaOH;
6 adăugați aditivi;
7 extend the oil immersion time.