Robust and advanced magnesium phosphate cement coatings achieved through surface modification of hollow glass microspheres by KH-560

Mitigating energy loss and corrosion in steel structures demands advanced protective coatings. Here we report a high-performance composite coating based on magnesium potassium phosphate cement (MKPC), integrated with titanium dioxide (TiO 2 ) and hollow glass microspheres (HGMs). A key innovation is the surface modification of HGMs with a silane coupling agent (KH560) to resolve their inherent interfacial incompatibility with the inorganic matrix. Comprehensive characterization confirms successful grafting of KH560, which fundamentally enhances filler-matrix interaction. The resulting coating exhibits significantly improved near-infrared reflectance due to the uniform dispersion of modified HGMs. Furthermore, micro-mechanical assessment reveals superior properties, including enhanced scratch hardness and elastic recovery, directly attributable to effective interfacial load transfer. Crucially, the incorporation of KH560-HGMs optimizes composite rheology, reducing both shear stress and apparent viscosity to ensure excellent sprayability. Microstructural analysis confirms a dense coating where modified HGMs act as nucleation sites for k-struvite, reinforcing the matrix. This interface engineering strategy provides a robust and generalizable route to durable, multifunctional MKPC-based coatings with tailored performance for sustainable infrastructure.