| About this Abstract |
| Meeting |
2021 TMS Annual Meeting & Exhibition
|
| Symposium
|
Coatings and Surface Engineering for Environmental Protection III
|
| Presentation Title |
Effects of Heat Treatments, Current Density, and Electroless Ni Layer Thickness on Corrosion Performance of Trivalent Chromium Passivations on ZnNi Coatings |
| Author(s) |
Kevin L. Foster, William G Fahrenholtz, Matthew J O'Keefe, James Claypool |
| On-Site Speaker (Planned) |
Kevin L. Foster |
| Abstract Scope |
A trivalent chromium based passivation (TCP) and a cobalt-free version of the same passivation (Co-Free) were studied on ZnNi coated, electroless nickel (EN) plated Al 6061-T6 substrates. Each panel had a 5-20 µm EN layer, 150 or 300 A/cm2 current density for plating the ZnNi, and either an 80°C or 191°C heat treatment after passivation. Corrosion performance was evaluated using image analysis of optical micrographs, and electrochemical testing, and ASTM B117 neutral salt spray exposure. Image analysis showed a performance difference between heat treatments, between EN layers with thicknesses >10 µm versus ≤10 µm, and between TCP and Co-Free passivation. Electrochemical testing revealed differences between 80°C and 191°C heat treatments. The results from this study indicate that the corrosion protection mechanisms are more dependent on passivation chemistry than the deposition and post-processing conditions. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Thin Films and Interfaces, Characterization, Other |