The system of lime, alumina, and water from 50-degrees to 250-degrees C

Til e sys tem CaO-Al, 0 3-H20 h a s been investigated over t h e range 50 to 250 0 C. At eq uili brium , only t wo stable ternary compounds exist in t h e system , namely , 3CaOAI,036H,O up to 215 C and 4CaO3Ab033H 20 from 215 to 250 C. H exago na l h yd rated calcium aluminates occu r as meta stable ph ases wi t h decreasin g stability with increasin g te mperature until a t temperatures over 100 C t h ey exist only momentarily. Tll ere are onl. v t wo stabl e alumina hydrates, nam ely, gibbsite (Ab033H, O) up to 150 C , and boehmite (AJ,03 H, O) thereafter. A stab le phase th rou ghou t th e te mperature ra nge is Ca(OH),. Th e equ ilibri a curves of th ese soli d phases maintain the same general mlatio nships to each oth er thl'oughou t. As t he temperat ure in creases to 250 C, th e solubili ty field s a re compressed in to th e ,,'ate l' apex of t he diagram.