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The evolution of the mold flux melt structure during the process of fluorine replacement by B 2 O 3
Author(s) -
Zhang Lei,
Wang Wanlin,
Zhai Bingyu,
Sohn Il
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16714
Subject(s) - borosilicate glass , fluorine , tetrahedron , crystallography , materials science , octahedron , ion , boron , chemistry , crystal structure , composite material , metallurgy , organic chemistry
This study presented the melt structure evolution of mold flux during the substitution of fluorine by B 2 O 3 , and a computational model for the degree of polymerization (DOP) for borosilicate structure was developed. The results showed that the reduction of fluorine content would promote the replacement of F in [SiF 6 ]‐octahedral unit by the dissociative free oxygen ions (O 2− ), and release F − ions into the melt to compensate the reduction of F − ions. With the 2 mass% addition of B 2 O 3 , the original Si–O–Si bond would be disrupted, and connect with [BO 3 ]‐trihedral to form boroxol ring structure containing [BO 2 O − ]‐trihedral and [BO 3 ]‐trihedral structural units. Then, the Si–O–B bond that [BO 3 ]‐trihedral links [SiO 4 ]‐tetrahedral in boroxol ring was destroyed with the further addition of B 2 O 3 , and then the [BO 3 ]‐trihedral could link with the dissociative Q 1 (Si) and Q 0 (Si) structural units to transform into [BO 4 ]‐tetrahedral and form a borosilicate long chain. Finally, with 6 mass% addition of B 2 O 3 , the borosilicate chain would combine with simple borate and borosilicate structures, and a complex borosilicate structure containing boroxol ring with certain symmetry was formed ultimately. Besides, the calculated result of DOP suggested that the DOP of the melt structure improved during the process of fluorine replacement by B 2 O 3 .