Preparation and performance of CaO-MgO-SiO2-Al2O3-CaF2 glass/Al2O3 ceramic with high flexural strength

•The CaO-MgO-SiO2-Al2O3-CaF2(CMSAC) glass was first used as a sintering aids for Al2O3 to enhance the flexural strength of composites.•The CMSAC glass/Al2O3 ceramic can be densified when sintered at 910 °C and has good dielectric and mechanical properties.•The CMSAC glass/Al2O3 ceramic has a high flexural strength of 310±14 MPa, which is higher than most LTCC materials reported previously.•The excellent mechanical properties are mainly attributed to three aspects: grain refinement, improved fracture energy, and the synergistic effect of the relative contents of Al2O3 and the CMSAC glass.