The influence of curing agents on thermal property and corrosion resistance of chemically bonded phosphate ceramic coatings

摘要

The curing agents play an important role on the properties of the chemically bonded phosphate ceramic coatings (CBPCs). To investigate the influence of curing agents on the thermal property and corrosion resistance of CBPCs, the coatings with different curing agents were prepared on the mild steel (Q235). The analysis of thermal property and phase characterization shows that the high peak temperature of curing decreases with the introduction of curing agents, and the weight ratio of AlPO4 to alpha-Al2O3 (RAA) of the coatings is also influenced by curing agents resulted by the high heat release from MgO, CaO, and ZnO-related reactions. In addition, the results of scanning electron microscopy (SEM) and electrochemical experiments reveal that the bonding strength among the ceramic particles and the defects content of the coatings, which affects the inhibition properties of CBPCs have a relationship with the value of RAA. Typically, the impedance value of CBPC with the best curing agent (MgO) are around 40,000 ohm cm(2), which is 4624 times larger than that of the bare mild steel (8.65 ohm cm(2)).