1. Scientific Foundations of Hollow Glass Microspheres one.1 Composition and Microstructure one.one.1 Chemical Composition: Borosilicate Dominance Hollow glass microspheres (HGMs) are mainly made up of borosilicate glass, a material renowned for its very low thermal expansion coefficient and chemical inertness. The chemical makeup typically incorporates silica (SiO₂, 50-90%), alumina ... https://omiyou.com/post/168078_metallic-boride-powders-are-very-unique-but-functional-new-ceramic-materials-the.html