Oxycarbide Glasses in the Mg‐Al‐Si‐O‐C System

Abstract

Oxycarbide glasses in the Mg‐Al‐Si‐O‐C system were produced at initial carbon levels of 0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 wt%. Carbon was incorporated into the glass melts by means of SiC additions. The glasses were melted between 1750° and 1800°C under nitrogen atmospheres. The limit of carbon incorporation was reached at the 2.5% carbon level, as these glasses crystallized (predominantly cordierite, 2MgO˙2Al 2 O 3 ˙5SiO 2 ) upon gradual cooling from the meit. Glasses containing less than 2.5% carbon were amorphous according to standard X‐ray diffraction methods. Further examination of these oxycarbide glasses by transmission electron microscopy indicated the lack of microcrystalline phases and the potential for producing clear inclusion‐free glasses. The Mg‐Al‐Si‐O‐C glasses showed significant increases in density, Young's elastic modulus, shear modulus, Vickers hardness, and fracture toughness with increasing carbon content.