1. Scientific Foundations of Hollow Glass Microspheres 1.one Composition and Microstructure one.1.1 Chemical Composition: Borosilicate Dominance Hollow glass microspheres (HGMs) are mostly made up of borosilicate glass, a material renowned for its very low thermal expansion coefficient and chemical inertness. The chemical makeup typically features silica (SiO₂, 50-90%), alumina (Al₂O₃, http://myworldgo.com/profile/okok0972/action_id/3410029/show_comments/1