| 摘要 |
FIELD: metallic protective coatings. ^ SUBSTANCE: method is realized by affecting coated test sample with salt mist for 12 h in a chamber at temperature 50±1°C and relative humidity 95±3%. Salt mist is created by spraying solution containing, g/L: NaCl 27.4, MgCl2 3.8, MgSO4 1.7, CaSO4 1.2, K2SO4 0.9, CaCO3 0.1, and KBr 0.13. Sample is then aired at air flow velocity 2.7 m/s, subjected to UV radiation for 5 min, and held during 12 h in the chamber. Sample mass loss is determined in time moments before appearance of bulky zinc corrosion products and appearance of the first steel corrosion site. In the mass loss (g)-time (days) graph, straight lines are drawn specifically so that point of intersection thereof allows determining protection ability of chromate film on zinc coating. Protection ability of chromated zinc coating tA pr (days), taking into consideration operation location thereof, is found from formula: tA pr = (CY Cl-/CA Cl-)ty n + 18(ty pr - ty n), where CY Cl denotes concentration of chlorides in chamber, mg/(m2*day); CA Cl- concentration of chlorides in ty n protection ability of chromate film on zinc coating, days; 18 is empirical coefficient of seaside atmosphere of operation location; acceleration of corrosion in chamber; and ty pr time moment before appearance of the first steel corrosion site, days. ^ EFFECT: increased accuracy in protection ability determination. ^ 3 dwg, 1 tbl |
