Influence of Ca/Al ratio on physical and dielectric properties of Al2O3/CaO-B2O3-SiO2 glass-ceramics composite coatings prepared by high enthalpy atmospheric plasma spraying

The dielectric layer plays a key role in regulating electromagnetic wave broadband scattering based on meta-surface technology. Herein, the physical properties of composite powder, prepared by spray drying of CaO-B 2 O 3 -SiO 2 (CBS) glass-ceramic powder and Al 2 O 3 in different mass ratios, are systematically investigated. Meanwhile, a high enthalpy atmospheric plasma spraying equipment is utilized to prepare CBS/Al 2 O 3 composite coatings , and the morphology, physical properties and dielectric properties of the composite coating are analyzed. The XRD and DSC data of the composite coating reveal that the crystallization behavior of β-CaSiO 3 and CaB 2 O 4 gradually disappear with the increase of Al 2 O 3 content. Hence, only CaAl 2 Si 2 O 8 phase is observed during heat treatment. The experimental results confirm that the dielectric properties of CBS/Al 2 O 3 composite coating conform to the rule of mixture for composite materials. Also, the dielectric properties are affected by porosity and crystallization rate.