How is the coefficient of expansion calculated?

Unit 7 Topic 14
Using Unity Formula

The coefficient of expansion is the accumulation of the expansions calculated for each individual oxide present in the unity formula of the glaze.
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Each oxide in a glaze has its own rate of expansion. The value of each oxide in the unity formula determines the impact of that oxide on the overall expansion for the glaze.

The coefficient of expansion for the whole glaze is found by totalling the expansions calculated for each oxide in the glaze.

In this example the oxides with the largest expansion calculated is the KNO group i.e. K2O & Na2O.

Have a look at the expansion factors for all of the oxides to see why the KNO calculated expansion is so high.
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Oxide

Mol. Parts
Calculated Individual Expansions
KNO
CaO
MgO
0.30
0.55
0.15
2.54
1.81
0.01
Al2O3
0.31
1.85
SiO2
3.20
1.8
Total Glaze Expansion >
8.01

The expansion for each oxide in the glaze is calculated then these are totalled to find the coefficient for the whole glaze.
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