Purify Argon gas by feeding it through heated titanium chips

[lou_skywalker]

If a titanium heat treatment process is to be performed in argon that has been passed over heated Ti chips prior to entering the furnace, should the gettering Ti (the ones used for purifying the argon) be at a higher or lower temperature that the parts being heat treated?

I know that a higher temperature is desired since the kinetics are more favorable but more oxygen will be removed if the temperature is not too high.

 

[Highway]

is this type of reaction usually exo or endothermic?

 

[lou_skywalker]

It should be exothermic

 

[uby]

Titanium getters typically operate around 600C.

Reactions between metals and oxygen tend to get less favorable with increasing temperature, resulting in a minimum oxygen potential your getter can achieve that increases with temperature (i.e., you can achieve lower oxygen potentials at lower getter temperatures). Take a look at the reaction constants for:

Ti + O2(g) = TiO2(rut.)
Ti + O2(g) = TiO2(ana.)
2Ti + O2(g) = 2TiO

The K values will be the reciprocal of the minimum achievable oxygen partial pressures. Be sure to use condensed phases that are stable in the temperature range you are examining. I don't know the range of stable temp. values for rutile, anatase, and TiO off-hand.

 

[lou_skywalker]

alright I will look into that...do you know why reactions are less favorable when you increase the temperature? Because it seems like at higher temperatures the kinetics are more favorable for reactions to occur.

 

[uby]

I only said reactions between oxides and metals tend to get less favorable with increasing temperature.

Kinetics almost always increase with temperature, but not always the thermodynamic driving force.