Calcium carbonate surface material loss

A typical product layer on a quartz particle after being reacted with calcium carbonate under dry CO2 conditions at 842°C can be seen in Fig. S(a), The sample consisted of 57-// quartz particles in a matrix of Ge I CaCOa. The weight loss data indicated a 46% reaction. Assuming Ca2Si04 as the reaction product, layer thickness measurements indicated a 58% reaction. The product layer for these conditions was observed to be well defined. The amount of reaction calculated from weight loss data agreed well with values calculated from product layer thicknesses on the basis of 20 different measurements. This agreement was found for all three calcium carbonate matrix materials and confirmed the HF acid test in that reaction was restricted to the quartz particle surfaces. 

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