Reaction Process of Fluorapatite-Silicon Tetrachloride System

Abstract

The reaction process between Ca00(PO4)5F2 and SiCl4 vapor uinder a vapor pressure of 501mmHg, which corresponds to the satuxated pressure at 450C, was studied and estimated as follows;
Caie(PO )6F2 gx/2 SiCl. Caie(PO )e(F2 pt C12x) x/2 SiF xgS l sOO (1)
ca (Po4)6C12 3/2 SiC14 3ca2P207 4cac12 3/2 sio2 ( 600 ) (2)
Cal (PO 6C13+2CaC1 6 CaapO Cl 1000 ) (3)
Ca2PO Cl 114 SiCk 112 CaAP207. CaC12 1/4 SiO2 (600ey900 C) (4)
Ca2P207+SiCli+SjO2, +CaC12 Amorphous phesphate ( 1: 8000C) (5)
The initial stage of the reaction process was alwaysReaction (1) at any tempetatures above 500°C. Through Reaction (1), ch1orine ion substituted fluorine ion, and then complete yt atilzaPiop, . of fluprine. result, ed. C, qig(PO4)6C12, interrpediate product, was decorppose. dA. tent. Ca2Pp7 through h3 116 g tw way T were mplex eac 2 (3) (4) a nd Reaction (3) at low and high tempdrati re tangess), t, p. s pectiVely
Ca2P 7 cha hged into an a: rriorphous p h Sphate (Reaction(5)) Thi amorphous at6ridl contained the phosphate ions with various Polymerization degtees, and had a e6Rsiderabl high solubility in an aqueeus solution of CaC12i
The reaetion rates. of. Re. action (1) and Reaction. (5) increased with the elevation of temperature, , whereas the rate of Reaction (4) gave, a maximu. m, value at about 7500C. The decomp6sition rate of Caie(PQD sC12 below 1.0000C was larger than tha, t above IQ, OOPP )