ISO 8994:2011 pdf download.Anodizing of aluminium and its alloys 一Rating system for the evaluation of pitting corrosion -Grid method.
3 Procedure for rating
3.1 Sample preparation
A sample area of more than 5 000 mm2 is required.
Use one of the following methods to remove corrosion products or deposits on the surface so that corrosion pits may be cleaKly discerned:
a) wipe with a slurry of fine pumice to abrade away corrosion products and dirt, then rinse in clean water and air dry;
b) dip for 5 mm to 10 mm in 30 % nitric acid, prepared by diluting 1 volume of concentrated nitric acid
(p = 1,40 glnll) wIth 1 volume of water at 20 C to 25 C; rinse and dry as indicated ri a); or
c) diSsolve the anodic oxidation coating in a hot phosphoric acid/chromic acid mixture nnse and dry as indicated in a) so that pitting in the aluminium substrate may be discerned;
NOTE 1 ISO 2106121 descnbes the preparation end use of this reagent for the purposes of dissolution of the anodic ocidabon mating
NOTE 2 This method is partiwlaily useful for dartc.coloured anodic oxidation coatings.
WARNING — Chromium(V1) is toxic and shall be handled properly. Chromium(Vl) solutions are hazardous to the environment and severely hazardous to waters.
or
d) wipe with soft textile gauze dipped in dilute hydrochloric acid solution (100 ml of 35 % to 37 % HCI, made up to 1 000 ml with distilled water or deionized water) to remove deposited copper, then rinse and dry as indicated in a)
3.2 Determination of grid rating
Ptace a preprinted transparent grid with an area of at least 5000 nvn2, and with grid squares of 5 mm x 5 mm. over a selected area of the significant surface of the prepared test specimen. Count the number of grid squares occupied by one or more pits, disregarding effects on the edges of samples. Calculate the percentage of defective squares, i.e. grid squares containing pits, using Formula (1).
3.1 Sample preparation
A sample area of more than 5 000 mm2 is required.
Use one of the following methods to remove corrosion products or deposits on the surface so that corrosion pits may be cleaKly discerned:
a) wipe with a slurry of fine pumice to abrade away corrosion products and dirt, then rinse in clean water and air dry;
b) dip for 5 mm to 10 mm in 30 % nitric acid, prepared by diluting 1 volume of concentrated nitric acid
(p = 1,40 glnll) wIth 1 volume of water at 20 C to 25 C; rinse and dry as indicated ri a); or
c) diSsolve the anodic oxidation coating in a hot phosphoric acid/chromic acid mixture nnse and dry as indicated in a) so that pitting in the aluminium substrate may be discerned;
NOTE 1 ISO 2106121 descnbes the preparation end use of this reagent for the purposes of dissolution of the anodic ocidabon mating
NOTE 2 This method is partiwlaily useful for dartc.coloured anodic oxidation coatings.
WARNING — Chromium(V1) is toxic and shall be handled properly. Chromium(Vl) solutions are hazardous to the environment and severely hazardous to waters.
or
d) wipe with soft textile gauze dipped in dilute hydrochloric acid solution (100 ml of 35 % to 37 % HCI, made up to 1 000 ml with distilled water or deionized water) to remove deposited copper, then rinse and dry as indicated in a)
3.2 Determination of grid rating
Ptace a preprinted transparent grid with an area of at least 5000 nvn2, and with grid squares of 5 mm x 5 mm. over a selected area of the significant surface of the prepared test specimen. Count the number of grid squares occupied by one or more pits, disregarding effects on the edges of samples. Calculate the percentage of defective squares, i.e. grid squares containing pits, using Formula (1).
