Substrate surface roughening improves the interfacial properties between steel rebar and low temperature enamel (LTE) coating

Enamel coating has potential application in steel rebar protection due to its high durability, excellent corrosion resistance, and strong coating/concrete interface bond. The newly developed low temperature enamel (LTE) coating has a substantially lower sintering temperature than that of traditional enamel coatings, whereas its adhesion mechanism to the substrate is expected to vary dramatically. In this study, abrasives of various particle sizes were used to blast steel substrates to create various surface states, to investigate the influence of substrate surface roughening on the interfacial properties of LTE coating. The surface roughness of substrates was quantitatively characterized by a 3D optical profiler. The adhesion, impact resistance, and abrasion resistance of LTE coating under different substrate surface states were investigated by pull-off, falling weight impact, and Taber abrasion test, respectively. The results showed that with increasing substrate surface roughness, the adhesion strength and impact resistance of the LTE coating were greatly improved. Within the investigated range, the substrate surface roughness had negligible influence on abrasion resistance. Overall, appropriate substrate surface roughening can provide the LTE coating with sufficient interface adhesion, impact resistance, and abrasion resistance.