Effect of ceramic-infused polymeric sealants on thermally sprayed 13% Cr steel coating properties

This study investigates the effectiveness of ceramic-infused polymeric sealants—specifically, SA (silicone resin + Al2O3), SS (silicone resin + SiO2), and SG (silicone resin + garnet powder)—in reducing porosity and improving the tribo-mechanical and corrosion properties of thermally sprayed 13% Cr steel coatings on a mild steel (SS400 grade) base. Among the tested combinations, SG sealants exhibited the best sealing qualities and thermal stability, maintaining the highest residual weight beyond 120℃ and achieving an optimal contact angle of 28º. The applied sealants significantly reduced porosity, with the SG sealant demonstrating the most substantial reduction, decreasing porosity from 3.2% to 2.72%. Microhardness testing revealed that the SG sealant significantly optimized hardness to 350 HV0.5, closely matching the 361 HV0.5 hardness of 13% Cr steel coatings. Both SA and SG sealants increased adhesion strength, from 18.8 to 21.1 MPa, respectively; also, the volumetric wear had 6.4E− 5 and 7.2E− 5 mm3/Nm, respectively. Furthermore, the SG sealant showed a lower friction coefficient (0.58 vs. 0.62 for the SA sealant), indicating that it had superior tribological properties. Corrosion resistance was improved across all sealant types, with the SA sealant having a corrosion rate of 1.52E− 07 mm/A.cm.yr and the SG sealant having a corrosion rate of 1.98E− 07 mm/A.cm.yr, resulting in relatively comparable rates. The SG sealant delivered optimal results and is more economical, highlighting the potential of ceramic-infused polymeric sealants for moderately elevated-temperature service conditions.