Ceramics-Silikáty 26, (4) 289 - 298 (1982)

Transition of CaO and SiO₂ into a silicate bond in the system calcite-quartz (molar ratio 1 : 1) at 700–1000 °C in air, hydrogen, CO₂, H₂O and in H₂O/CO₂ mixtures can be described by the exponential equation α_i = 1 - exp(-Bt²), in which the value z is constant and indicative of a diffusion mechanism of the controlling process. Constant B is a function of the firing atmosphere composition. Water vapour likewise accelerates the combination of the components into silicate bonds in the temperature region below 1000 °C, which has not so far been investigated experimentally. In CO₂-containing atmosphere, the silicates are produced by direct reaction of calcium carbonate with quartz. The reaction mechanism is based on surface diffusion of Ca²⁺ ions through the polycrystalline layer of the products, namely C₂S and CS.