plante1999
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production of titanium silicide
today i trty to make titanium silicide , the reaction product are fine to use. so i take a consentred solution of TiCl3 in glass test tube and a HF
generator on anoter test tube (i know, the glass become H2SiF6) so i active the hf generator and bublet it with poly tube in the TiCl3 solution ,
imediatly a grayish white precipitate formed , after testing this mater correspond to the broer description of titanium silicide my question is at
wath temperature the H2SiF6 become gas and if i take a steel HF generator and a plastic test tube , does it will precipitate TiF3 (the TiF3 is
insolube in water).
i will post some picture later
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blogfast25
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Quote: Originally posted by plante1999  | | today i trty to make titanium silicide , the reaction product are fine to use. so i take a consentred solution of TiCl3 in glass test tube and a HF
generator on anoter test tube (i know, the glass become H2SiF6) so i active the hf generator and bublet it with poly tube in the TiCl3 solution ,
imediatly a grayish white precipitate formed , after testing this mater correspond to the broer description of titanium silicide my question is at
wath temperature the H2SiF6 become gas and if i take a steel HF generator and a plastic test tube , does it will precipitate TiF3 (the TiF3 is
insolube in water). |
You're bubbling the highly dangerous HF from one test tube into another without much precautions? Do you know just how dangerous HF
is???
One very possible way is to thermite a mixture of TiO2 and SiO2 in the correct molar ratios (presumably 1:1 for TiSi). TiO2 and SiO2 have almost
identical heats of formation and in normal circumstances will not be thermited with Al metal. However, by adding to the mixture also KClO3, extra Al
and CaF2 (fluorite, as a flux), it’s possible to obtain both metals. KClO3 plays the role of a heat booster (KClO3 + 2 Al === > KCl + ½ Al2O3).
A typical molar formulation would thus be:
.................mol
TiO2…………1/2
SiO2…………1/2
Al…………....4/3 + 2x
KClO3……….x
CaF2…………y
With x typically 0.4 – 0.5 mol.
Should also work with other heat boosters like KClO4, KNO3 or even CaSO4...
[Edited on 18-2-2011 by blogfast25]
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plante1999
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like i sayd in many of my post , i have horror of HF , but the reation was controled at -10 degree c with a layer on the top of the TiCl3 of kerosene
/ NaOH withch neutralise the solution.
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blogfast25
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| Quote: Originally posted by plante1999 | | like i sayd in many of my post , i have horror of HF , but the reation was controled at -10 degree c with a layer on the top of the TiCl3 of kerosene
/ NaOH withch neutralise the solution. |
Read your OWN post again: it says NOTHING about neither your 'horror of HF', nor about '- 10 degrees c'...
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plante1999
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sorry , for the missing part , in a frencophone and i rigth on word my test correct some error ect than i post , probably i forgot to underline a
part.
i will patch the part missing" where i am the temperature outside is -10 to -25. the recever test tube was in the snow outside , when i make
experiment with TiCl3 solution i find that kerosene float on the top of the solution , so i maked a solution kerosene / NaOH for neutralising the HF.
the verry dengerous part of this prosses is use HF in glass , witch corode with HF''
sorry for this incomplete post i have made. for the ''I HAVE HORROR OF HF'' i refert to my old post about fluorinating zirconium and titanium.
thank!
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blogfast25
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Do you think you could explain your method for titanium silicide a little better? It doesn’t make a great deal of sense to me.
You also claimed “after testing this mater correspond to the broer description of titanium silicide”. I assume you meant ‘Brauer’.
What did you do that confirms your precipitate corresponds to Brauer’s description?
Also, it looks like the silicide you're referring to is TiSi2, according the literature...
[Edited on 19-2-2011 by blogfast25]
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plante1999
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the gray-white precipitate , insolube in consentred mineral acid and alkali.
firts test tube:
2NaF + H2SO4 -> 2HF + Na2SO4
6HF+SiO2 -> H2SiF6 + 2H2O
receiver test tube:
first layer:
6HF+SiO2 -> H2SiF6 + 2H2O
8 H2SiF6 + 22 H2O + 4 TiCl3 -> 4 TiSi2 + 48 HF + 12 HCl + 11 O2
second layer
HF + NaOH -> NaF + H2O
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blogfast25
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Note that any gas coming over from your glass HF generator would be mainly HF with some SiF4 (H2SiF6 only exists in solution).
Well, TiF3 is deep blue/purplish so a whitish/grey precipitate is unlikely to be TiF3.
But TiO2 (white!) also would not dissolve in mineral acids or alkalis either. TiO2 would of course form by oxidation of Ti3+ with water:
Ti3+ + 2 H2O === > TiO2 + 4 H+ + e- (1)
… assuming there’s something that will capture that electron, like oxygen or any other oxidiser.
Whether TiSi2 would form rather than TiF3 would largely depend on the solubility product of TiF3 = [Ti3+]x[F-]^3 for which I have no value. In a
strongly acidic TiCl3 (necessary to prevent (1) from happening) the concentration of F- would be very small because HF is quite a weak acid:
HF + H2O < === > H3O+ + F- has an equilibrium constant of about E-3.17, so for high concentrations of H3O+, the concentration of F- is very much
suppressed.
NaOH is not very soluble in kerosene and would tend to phase transfer in contact with an acid watery phase...
[Edited on 19-2-2011 by blogfast25]
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