The corrosion performance was studied for standard trivalent chromium passivations and cobalt-free trivalent chromium passivations on steel substrates. The steel substrates were either polished or unpolished and coated with γ-phase ZnNi prior to passivation. For unpolished substrates, cobalt-free specimens had 50 ± 8 cracks/mm, a thickness of 69 ± 4 nm, and notable porosity compared to cobalt-containing passivations which had no cracks, a thickness of 40 ± 5 nm, and no porosity. For polished substrates, cobalt-free passivations had 50 ± 3 cracks/mm, a thickness of 38 ± 2 nm, and notable porosity compared to cobalt-containing passivations with 16 ± 2 cracks/mm, thickness of 48 ± 2 nm, and no porosity. After 1000 hours of salt-spray exposure, cobalt-free passivations had visible white rust on 4% of the surface area while cobalt-containing passivations had 22% of the surface area covered by white rust. The thickness of both passivations increased on both polished and unpolished specimens after salt spray exposure. Electrochemical testing showed that the cobalt-free passivation had the least change before and after salt spray exposure. The difference in corrosion performance was attributed to the greater porosity in the cobalt-free passivations influencing the amount of corrosion inhibiting species present.

研究了钢基材上标准三价铬钝化层和无钴三价铬钝化层的腐蚀性能。在钝化之前，钢基体被抛光或未抛光并涂有γ相ZnNi。对于未抛光的基板，与没有裂纹、厚度为 40 ± 5 nm 且没有孔隙率的含钴钝化相比，无钴样品具有 50 ± 8 裂纹/mm、69 ± 4 nm 的厚度和显着的孔隙率。对于抛光基板，无钴钝化具有 50 ± 3 裂纹/mm，厚度为 38 ± 2 nm，与具有 16 ± 2 裂纹/mm，厚度 48 ± 2 nm 的含钴钝化相比显着的孔隙率，并且没有孔隙率。盐雾暴露 1000 小时后，无钴钝化在 4% 的表面积上有可见的白锈，而含钴钝化有 22% 的表面积被白锈覆盖。盐雾暴露后，抛光和未抛光样品的钝化层厚度均增加。电化学测试表明，无钴钝化在盐雾暴露前后变化最小。腐蚀性能的差异归因于无钴钝化层中更大的孔隙率影响存在的腐蚀抑制物质的数量。电化学测试表明，无钴钝化在盐雾暴露前后变化最小。腐蚀性能的差异归因于无钴钝化中更大的孔隙率影响存在的腐蚀抑制物质的数量。电化学测试表明，无钴钝化在盐雾暴露前后变化最小。腐蚀性能的差异归因于无钴钝化中更大的孔隙率影响存在的腐蚀抑制物质的数量。