Rankin and Wright — Ternary System CaO-Al n 2 -Si0. 2 . 67 



crystallization curve has reached the boundary curve 13-12 

 (fig. 17) along which 2CaO.Al 2 3 .Si0 2 and CaO.A! 2 3 crys- 

 tallize together ; until at a temperature of 1505° the eutectic 12 

 is reached, when 2CaO. Al,0 3 .Si0 2 , CaO. A1 2 3 and 3Ca0.5 A1 2 3 

 separate together. 



Table XXI. 



Examples of crystal phases present during the course of a crystallization 



curve of the simplest type for a ternary system. 



Composition 

 weight percentage Temp. Phases Present 

 CaO A1 2 Q 3 SiQ 2 



38 51-5 10-5 1540 Glass 



1520 Glass + 2CaO.Al 2 3 .Si0 2 



1515 Glass + 2CaO. Al 2 O s Si0 2 + CaO.Al 2 3 



1505 Glass + 2CaO. Al 2 3 Si0 2 + CaO. A1 2 3 + 



3Ca0.5Al,0 3 



52 38 10 1470 Glass 



1450 Glass 4- Ca 2 Si0 4 



1410 Glass + Ca 2 Si0 4 



1340 Glass + Ca 2 Si0 4 + 5Ca0.3Al 2 3 

 1330 Ca a Si0 4 + 5Ca0.3 A1 2 3 + CaO. A1 2 3 



52-5 42-5 5 1405 Glass 



1380 Glass + 3CaO.Al 2 3 

 1350 Glass + 3Ca0.Al,0 3 + 5Ca0.3Al 2 3 

 1325 3CaO.Al 2 3 + 5Ca0.3Al 2 3 4-Ca 2 Si0 4 



The data in Table XXII illustrate that type of crystallization 

 which follows a boundary to a quintuple point not a eutectic. 

 So far as the data show, this type of curve is the same as that 

 given in Table XXI ; the only difference is that when the tem- 

 perature 1380°=b5° of the quintuple point (13) is reached, 

 the compound 2CaO.Al 2 3 .Si0 2 partially disappears while 

 2CaO.Si0 2 crystallizes. 



Table XXII. 



Examples of crystal phases present during the course of a crystallization 



curve which ends at a quintuple point not a eutectic. 



Composition 

 Weight — percentage Temp. Phases Present 



CaO A1 2 3 Si0 2 



~45 43 T 5 IvE 1490 Glass + 2CaO. Al 2 G 3 .Si0 2 



1450 Glass + 2CaO. Al 2 3 .Si0 2 + CaO.Al,0 3 



1385 Glass + 2CaO. Al 2 3 .Si0 2 + CaO. Al.O, + Ca,Si0 4 

 1375 2CaO. Al 2 3 .Si0 2 + CaO. A1 2 3 + Ca 2 Si0 4 



47-5 37-5 15 1500 Glass + 2CaO.Al 2 0,.Si0 2 



1475 Glass + 2CaO. Al 2 0;.Si0 2 + Ca 2 Si0 4 



1400 Glass + 2CaO. Al 2 O a Si0 2 + Ca 2 Si0 4 

 1350 2CaO. Al 2 3 .Si0 2 + Ca 2 Si0 4 -{- CaO. A1 2 3 



