Environmentally friendly magnesium potassium phosphate cement-based coating with high anti-corrosion performance on iron

Magnesium potassium phosphate cement-based (MKPC) coating is regarded as an attractive green coating that improves the corrosion resistance of metals. Unfortunately, practical use remains challenging owing to the rapid solidification and hardening of MKPC coating. To overcome this issue, this work proposes a novel strategy to substitute a portion of potassium dihydrogen phosphate (KDP) with dipotassium hydrogen phosphate trihydrate (DKP) as phosphate source. Samples with or without KDP replacement were named KDP-DKP cement/coating and KDP cement/coating, respectively. The initial condensation time of KDP-DKP coating is more than 3 h, which is longer than that of KDP coating and can demand the actual construction needs. The anti-corrosion performance results display that protection efficiency (Pe%) of KDP-DKP coating is 95.33%, which is higher than 87.56% of KDP coating, indicating that the anti-corrosion performance of KDP-DKP coating is superior than that of KDP coating. Furthermore, durability and anti-corrosion mechanism of KDP-DKP coating were also investigated and explored through immersion and potentiodynamic polarization tests. The consequences demonstrate that KDPDKP coating has excellent durability, and both magnesium and phosphate ions in the coating suppress the corrosion rate of Fe. In summary, this work developed a durable and eco-friendly MKPC coating, which provides feasible guidance for the practical application of MKPC anti-corrosion coating.