In‐Depth Microstructural Evolution Analyses of Cement‐Bonded Spinel Refractory Castables: Novel Insights Regarding Spinel and CA 6 Formation
Calcium hexaluminate ( CaO ·6 Al 2 O 3 – CA 6 ) is usually associated as the product reaction between alumina and CA 2 ( CaO ·2 Al 2 O 3 ) in cement‐bonded refractory castables. However, some investigations related to the Al 2 O 3 – CaO – MgO ternary system have indicated that CA 6 could be generate...
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| Published in | Journal of the American Ceramic Society Vol. 95; no. 5; pp. 1732 - 1740 |
|---|---|
| Main Authors | , , , , |
| Format | Journal Article |
| Language | English |
| Published |
01.05.2012
|
| Online Access | Get full text |
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| Summary: | Calcium hexaluminate (
CaO
·6
Al
2
O
3
–
CA
6
) is usually associated as the product reaction between alumina and
CA
2
(
CaO
·2
Al
2
O
3
) in cement‐bonded refractory castables. However, some investigations related to the
Al
2
O
3
–
CaO
–
MgO
ternary system have indicated that
CA
6
could be generated by additional routes, involving two other high‐alumina phases:
CaMg
2
Al
16
O
27
(
CM
2
A
8
) and
Ca
2
Mg
2
Al
28
O
46
(
C
2
M
2
A
14
). Considering the lack of conclusive studies on this subject in the refractories field, the present study addresses an in‐depth microstructural evolution analysis of high‐alumina castables containing
in situ
or preformed spinel (
MgAl
2
O
4
) in order to check the actual
CA
6
development steps in the presence of an
MgO
‐containing phase. By scanning electron microscopy (
SEM
) and thermodynamic calculations, it was observed that
CA
6
formation took place indeed as a result of the decomposition reaction of
CM
2
A
8
, which was firstly generated due to the interaction between spinel and
Al
2
O
3
–
CaO
–
Na
2
O
–
SiO
2
liquid. Although, the results confirmed this complex
CA
6
formation route regardless of the spinel incorporation method (pre‐formed grains addition or
in situ
reaction), the
CA
6
crystals distribution after the thermal treatment was entirely affected by the previous spinel grains location. Those different microstructural profiles could be the conclusive aspects to explain the poorer slag resistance of preformed spinel‐containing castables when in contact with steel ladle slags. |
|---|---|
| ISSN: | 0002-7820 1551-2916 |
| DOI: | 10.1111/j.1551-2916.2012.05161.x |