COATING α-Al(OH)_3 ON ARAGONITE CALCIUM CARBONATE WHISKER THROUGH CARBONATION PROCESS
A carbonation process was developed to coat Al(OH) 3 on aragonite whisker. Al(OH) 3 coating was obtained in a suspension,which contained 3Cao·Al 2O 3·6H 2O(C 3AH 6)-NaOH prepared by adding Ca(OH) 2 to NaAlO 2 aqueous solution.The CaCO 3 whiskers coated with fine particles of Al(OH) 3 were prepared by blowing CO 2 gas into the suspension.The formed Al(OH) 3 adhered to the CaCO 3 fibers as the substrate.In order to coat α -Al(OH) 3 on aragonite whisker , the pH value of the solution must be higher than 10.5.The formation of C 3AH 6 and complexation of calcium carbonate molecule with C 3A were the domain factors to get single aragonite phase whisker. Micro-analysis demonstrated that the existence of Al(OH) 3 crystal coating on the surface of aragonite-type calcium carbonate whisker.After the coated whiskers were treated strongly in an ultrasonic water bath.Al(OH) 3 still adhered to the CaCO 3 whiskers well.The reaction mechanism was also mentioned in this paper.