Introduction
Experimental Procedure
Test Specimens and Treatment Procedures
No. | Concentration (M) | Aging time, m | pH | |||
---|---|---|---|---|---|---|
Na2Al2O4 | Zn(NO3)2·6H2O | NH4NO3 | KNO3 | |||
1 | 0.05 | 0.01 | 0.01 | 0.10 | 120 | 11.5 |
2 | 0.13 | 0.01 | 0.01 | 0.10 | 120 | 12.0 |
3 | 0.15 | 0.01 | 0.01 | 0.10 | 120 | 12.3 |
4 | 0.20 | 0.01 | 0.01 | 0.10 | 120 | 12.4 |
5 | 0.25 | 0.01 | 0.01 | 0.10 | 120 | 12.6 |
6 | 0.25 | 0.01 | 0.01 | 0.10 | 180 | 12.7 |
7 | 0.25 | 0.01 | 0.01 | 0.10 | 240 | 12.9 |
8 | 0.25 | 0.01 | 0.01 | 0.10 | 480 | 13.2 |
9 | 0.25 | 0.01 | 0.01 | 0.10 | 120 | 13.3 |
Evaluation of Corrosion Resistance
Analyses of Coating Layer
Results
Corrosion Resistance
Analysis of Coating Layer
Discussion
Effect of Conversion Coating Layer Thickness on Corrosion Resistance
Effect of Solution pH on Microstructure of Coating Layer
Analyzed area | Composition at.% | |||
---|---|---|---|---|
Al | Zn | O | C | |
1 | 15 | 35 | 46 | 3 |
2 | 11 | 41 | 43 | 5 |
3 | 0 | 95 | 2 | 2 |
4 | 13 | 37 | 48 | 4 |
5 | 1 | 59 | 39 | 2 |
6 | 0 | 96 | 2 | 2 |
7 | 13 | 34 | 47 | 6 |
8 | 1 | 51 | 55 | 2 |
9 | 0 | 54 | 44 | 2 |
10 | 0 | 95 | 3 | 3 |