Effect of inorganic silicate sealing treatment on corrosion behaviour for HVAF sprayed Fe-based amorphous coatings

ABSTRACT

Sealing treatment is an effective, environmentally friendly, and economical coating surface modification technology. To clarify the inorganic silicate sealing mechanism and concentration dependence on corrosion behaviour, HVAF-sprayed Fe-based amorphous metallic coatings (AMCs) were sealed by Na₂SiO₃ solution with various concentrations, and their microstructure, electrochemical performance, and surface chemistry were characterised in detail. The results showed that Na₂SiO₃, in the form of a silicon-oxygen bond (Si-O), could effectively bond with the coating surface inside the pore defects. In addition, the optimal concentration was proved to be 1 mol/L, and the corresponding passivation current density could be reduced to (2.38 ± 0.33) × 10⁻⁶A/cm², which was an order of magnitude lower than that of as-sprayed coating. This was due to the incomplete filling of the sealant at lower concentrations and the release of water vapour at higher concentrations. This work aims to provide guidance for the practical application of silicate sealing treatment.

KEYWORDS:

• Corrosion prevention
• thermal spraying
• Fe-based amorphous metallic coating
• sealing treatment
• passive film
• pore defect
• polarization
• silicate

Acknowledgements

The authors wish to express the gratitude to Mr. D.B. Wang from IMR, CAS, China, for the assistance in improving the efficiency of data processing

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability

The raw/processed data required to reproduce these findings are available from the corresponding author upon request.

CRediT authorship contribution statement

Jinghui Ren: Methodology, investigation, writing – original draft, writing – review and editing, and resources. Tianrun Li: Methodology, data curation, and resources. Suode Zhang: Methodology, data curation, resources, and writing – review and editing. Min Xu: Methodology, data curation, resources, and writing – review and editing. Jianqiang Wang: Conceptualisation, methodology, writing – original draft, writing – review and editing, resources, and project administration.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Nos. U1908219, 52171163 and 52271157), the Key Research Program of the Chinese Academy of Sciences (No. ZDRW-CN-2021-2-2), the National Key Research and Development Program of China (No. 2022YFF0609002), and the Key Research & Development Plan of Jiangxi Province (No. 20192ACB80001).