Ivor and Olive Lewis on tue 31 jan 06
Dear Friends,
Following the entries of Mel and that summary of his discussion with =
Nils I have compiled a short list of Oxides ( I am ignoring newer high =
tech non oxide ceramic compositions) that might have the capability of =
withstanding the onslaught of Sodium Chloride.
Starting from a base line melting point higher than 1900=BA Celsius ( =
3452=BA F) and a Thermodynamic factor known as Heat of Formation, (a =
measure of the heat given out when the pure element is oxidised, so it =
has a Negative value and we want the most negative values). I drew the =
line to select those with a value lower than minus 1000 kilojoules per =
Mol. Also of interest is the Heat of formation of the metallic Chloride. =
This must be closer to zero than the value for the oxide. Nor should =
there be any phase changes.
The short list reads;
Aluminium Oxide.
Dysprosium Oxide.
Neodymium Oxide.
Tantalum Oxide.
Note, this is a proposition not a statement of irrefutable fact. It =
should be tested by thermodynamic calculation, reference to the general =
chemistry notes for each compound and experimental observation from site =
testing.
In the original list Rare Earth Oxides featured strongly.
I hope some of you find this interesting reading
Best regards.
Ivor Lewis.
Redhill,
South Australia.
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