CO_2 処理による CaSiO_3 の固化機構(<特集>セラミック材料)

概要

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The consolidation mechanism of calcium silicate with water under carbonation was investigated. CaSiO_3 powder was activated by mechano-chemical treatment for 24h in air with a vibration ball-mill. The cakes of the vibration ball-milled CaSiO_3 added with a fair amount of water were carbonated at 50℃ in 0.33MPa CO_2 for 0.5 to 6hrs. in order to obtain the specimens carbonated to different degrees. The microstructural development in this carbonation process was observed by transmission and scanning electron microscopy and ^<29>Si-MAS NMR, and the pore size distributions of the consolidated bodies were evaluated by mercury intrusion and N_2 gas adsorption methods. By this carbonation treatment, dense consolidated bodies were obtained which exhibited high compressive strength. In the carbonated specimen, needle like crystals of aragonite precipitated to fill up macro-pores, and particles coalesced to form continuous matrices. The results of ^<29>Si-MAS NMR showed that Q^2 structure of SiO_2 component assignable to single silicate chains transformed into Q^4 structure indicative of three-dimensional SiO_2 networks. These experimental results suggest that carbonation-induced consolidation would be caused by poly-condensation of SiO_2 component in CaSiO_3.
社団法人日本材料学会の論文
2003-06-15