Abstract: The presence of high porosity, intrinsic brittleness, and the lack of self-healing capability can lead to irreversible damage to chemically bonded phosphate coatings (CBPC) during long-term service. Consequently, there is an urgent need to develop advanced phosphate coatings that not only overcome these inherent deficiencies but also exhibit enhanced corrosion resistance, wear resistance, and self-healing capabilities. Inspired by the adhesion strategy of snails, microcapsules (MC) encapsulating 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) are grafted chemically onto the surface of Ti₃C₂T_x amino-functionalized by silane coupling agent (k-Ti₃C₂T_x), thereby constructing a functional filler (k-Ti₃C₂T_x-MC) with a multiscale architecture. The resultant coating (k-Ti₃C₂T_x-MC@CBPC) exhibits the lowest corrosion current density (5.216 × 10^-7 A/cm²), accompanied by a high inhibition efficiency of 91.67 %. The low-frequency impedance modulus increased by approximately two orders of magnitude relative to CBPC. The coating demonstrates excellent self-healing ability during prolonged immersion in corrosive environments. This self-healing behavior is attributed to the crosslinking of PFDTES, released from the microcapsules, which generates a silane network that enhances the hydrophobicity, interfacial bonding strength, and cohesion. A physical barrier is established, with Ti₃C₂T_x acting as the carrier and the silane film as the main body, effectively retarding or blocking the diffusion of corrosive agents, thereby enhancing both the corrosion resistance and self-healing performance of the coating. Additionally, the silane film lubricates synergistically with Ti₃C₂T_x to reduce both the friction coefficient (0.3) and wear rate (1.93 × 10^-5 mm³/(N m)) of the coating. The interfacial design strategy for functional fillers proposed in this study lays the foundation for the development of novel phosphate coatings that provide new insights into metal protection in harsh environments.

Key words: MXene, Phosphate coatings, Corrosion, Wear, Self-healing