1. Scientific Foundations Of Hollow Glass Microspheres one.1 Composition and Microstructure one.1.1 Chemical Composition: Borosilicate Dominance Hollow glass microspheres (HGMs) are mainly made up of borosilicate glass, a material renowned for its small thermal expansion coefficient and chemical inertness. The chemical make-up usually features silica (SiO₂, 50-90%), alumina (Al₂O₃, te... http://www.mysportsgo.com/profile/okok0972/action_id/1516636/show_comments/1