QUALANOD aluminum anodizing: part 2
See. part 1 - Flushing, travlenye, anodizing
filling the anodizing coating technology, which are based on methods, other than "hydrothermal filling"Or" cold soaking ", It can not be used without special tests and approval QUALANOD organization.
Cold filling is called "cold", because it occurs at significantly lower temperatures, than hot filling. Unlike hot fill, based on the hydration process, cold filling "working" on a chemical reaction between aluminum oxide and nickel fluoride. For this reason, “clean” cold filling without additional hot working is often referred to as non-sealing., impregnation.
5. hydrothermal filling
Sealing duration. Sealing duration, necessary for good filling, shall be not less than 2 minutes of 1 Coating thickness microns.
Filling in hot water. The water temperature in the bathtub filling should be below 96 ° C within, than 10 min after immersion therein cages.
phosphate, fluorides and silicates slow down (inhibit) the filling process.
filling the steam. Minimum processing temperature must be the temperature of saturated steam.
6. Cold impregnation / cold filling
6.1. First stage of treatment: impregnation
Nickel ion content: from 1,2 to 2,0 g / l
Free fluorine ions: from 0,5 to 0,8 g / l
The concentration of contaminants filling a bath, that can slow the process of cold filling, must be no higher than those indicated below:
sodium or potassium ions - 300 ppm;
ammonium ions - 1500 ppm;
sulphate ions - 4000 ppm;
phosphate ions - 5 ppm;
aluminum ions - 250 ppm.
If the bath is contaminated filling several of these substances, the "bad" content can occur at lower concentrations.
Bath temperature: from 25 to 30 oC.
PH size: 6 ± 0,5.
Duration of impregnation: from 0,8 to 1,2 min / micron anodic coating.
Rinsing: after impregnation, rinsing in cold water is mandatory.
6.2. The second stage processing: aging in hot water
To complete the CI-CS-treated in the first stage of the product should be placed for some time in an environment with very high humidity. For this, two processing options are used:
1) standard treatment in water at a temperature not lower than 96 oC, but during the time of the calculation of the 0,8 to 1,2 minutes for each micrometer of anode coating;
2) in a solution of nickel sulfate at its concentration from 5 to 10 g / l at a temperature not lower than 60 ° C for a time in a proportion of 0,8 to 1,2 minutes per micrometer of anodizing.
Thorough rinsing between cold impregnating and treating in the hot water entirely obligatory, since fluoride ions can inhibit (slow down) the process of hydrothermal filling.
Anodic coating after cold impregnation is more susceptible to cracking, than after hydrothermal conventional filling, special, if it is placed in warm dry atmosphere. Processing in hot water after cold impregnating coating significantly improves crack resistance of.
6.3. Filling Quality Control
If the process of "cold-impregnation / cold filling" as performed as described above, including treatment in hot water, the coating may be filled with the same testing methods, as usual hydrothermal filling.
The most suitable control methods are:
- "Drop method" in accordance with EN 12373-4 (ISO 2143) and
- weight loss method in accordance with EN 12373-7 (ISO 3210).
On the test methods and criteria for their results, see. Test methods anodic oxide coatings.
Source: QUALANOD Specifications