Si3N4 Bonded silicon carbide brick is a completely new type of refractory material, in which Si3N4 exists between SiC grains in needle-formed or fibrous crystalline form. Dec 28, 2018 #7 The flat surface doesn't must be glass, in fact glass just isn't that hard. It could be anything reasonably hard http://felixkqbw385.fotosdefrases.com/17-reasons-why-you-should-ignore-sintered-silicon-carbide