Michael Banks on wed 8 dec 99
I am currently interested in the colouring effects of the trace element
content (V,Mn,Nb,Ta,Cr) in rutile. Preliminary indications are that
chromium content of Australian rutile has a significant effect in some
glazes. Can anyone provide anaytical specs for other rutiles, e.g. African,
Floridian (USA, Floridonian..) rutiles?
The Australian rutile specs are:
TYPICAL SPECIFICATIONS FOR AUSTRALIAN RUTILE PRODUCTS
Product 1 Product 2 Product 3
TiO2 95.8 96.0 - 96.5 95.50
Fe2O3 0.94 0.50 - 0.80 0.53
ZrO2 0.80 0.50 - 0.80 0.80
SiO2 0.60 0.60 - 0.90 0.90
Cr2O3 0.15 0.18 - 0.28 0.14
Al2O3 0.27 0.30 - 0.80 0.25
P <0.025 n.a. 0.02
MnO 0.01 n.a. n.a.
CaO <0.02 0.01 - 0.06 0.02
MgO 0.02 0.08 - 0.14 0.04
V2O5 0.43 0.58 - 0.65 0.61
Nb2O5 0.34 0.38 - 0.45 0.41
S <0.02 0.01 - 0.025 0.01
SnO2 0.015 n.a. 0.03
(Courtesy of Yolanda Strauss, TZ Minerals International, Perth, W.A.)
Michael Banks,
Nelson,
New Zealand
John K Dellow on thu 9 dec 99
Michael , I can give you the following analysis of our local
rutile.
Currumbin Minerals
TiO2 95.05 %
Fe2O3 0.71 %
ZrO2 0.71 %
V2O5 0.6 - 0.8 %
Nb2O5 0.3 - 0.35%
Sieve Analysis ( to Bs 1796 : 1952)
Though a `75 micron British Standard BS 410 : 1969 test sieve .
But can you tell me what Nb2O5 is ! :).
John Dellow "the flower pot man"
Home Page http://www.welcome.to/jkdellow
http://digitalfire.com/education/people/dellow/
Michael Banks on fri 10 dec 99
John Dellow wrote:
> Michael , I can give you the following analysis of our local
> rutile.
>
> Currumbin Minerals
> TiO2 95.05 %
> Fe2O3 0.71 %
> ZrO2 0.71 %
> V2O5 0.6 - 0.8 %
> Nb2O5 0.3 - 0.35%
> Sieve Analysis ( to Bs 1796 : 1952)
> Though a `75 micron British Standard BS 410 : 1969 test sieve .
>
> But can you tell me what Nb2O5 is ! :).
Your local Queensland rutile John, seems to be a medium-iron one compared to
the TZ Minerals range. But it is lower in titanium than the W.A. specs. How
dark is it? There is 2.3% missing which I presume is silica, alumina etc,
but it could also include unreported chromium oxide, which is a potential
muddier of high-zinc glazes.
Nb2O5 is niobium oxide (Nb is also known as columbium), the oxide of a
period five transition metal element. Some rutiles can have very high Nb2O5
contents (over 8%). Nb is used in stainless steel alloys to impart strength
at high temperatures for use in the turbine blades of jet engines for
example. In jewellry it is used to make items with intense iridescence. In
glazes it can produce blues.
Niobium is usually accompanied in rutile by tantalum oxide (Ta2O5), which
the rutile producers don't seem to include in their published analyses for
some reason. Ta2O5 contents of over 15% are known in some rutile from the
west Pilbara, Western Australia. I haven't a clue what tantalum does in a
glaze, but someone out there might know?
What is interesting about all this, is when you add rutile to a glaze you
are getting a melange of transition element oxides (other than Ti and
Fe) -of some potential for affecting colour and texture.
Michael Banks,
Nelson,
NZ
Tom Buck on sat 11 dec 99
John:
Nb2O5 is niobium pentoxide, and Niobium itself is a group VB
transition metal (the other VBs are Vanadium and Tantalum). This is a most
expensive metal probably 2-3 dollars per gram so one would not go looking
for Nb2O5 for ceramic use. If it occurred in a material, chances are it
would behave somewhat as V2O5 does (browns, greys, perhaps an off-yellow
in some mixes).
Happy holidays. Peace. Tom B.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
Fredrick Paget on sun 12 dec 99
Tom,
The little metal tubes that are inserted into the ends of the pure
translucent aluminum oxide ceramic tubes used inside high pressure sodium
lamps are niobium metal. They are glued in with some kind of frit melted
in place. The metal was selected because of thermal expansion and chemical
resistance considerations.
I once had a small stash of these tubes and tried to make them into Nb2O5
by calcining them in a small Scutt kiln. They partially vaporized or
sublimed and contaminated the bricks nearby and subsequent firings were
ruined by a sort of wrinkled appearance on the glazes. It took 4 or 5
firings to burn the stuff out of the brickwork.
Fred Paget. And may you have a Happy Y2k.
> Nb2O5 is niobium pentoxide, and Niobium itself is a group VB
>transition metal (the other VBs are Vanadium and Tantalum). This is a most
>expensive metal probably 2-3 dollars per gram so one would not go looking
>for Nb2O5 for ceramic use. If it occurred in a material, chances are it
>would behave somewhat as V2O5 does (browns, greys, perhaps an off-yellow
>in some mixes).
> Happy holidays. Peace. Tom B.
>From Fred Paget, Marin County, California, USA
Michael Banks on sun 24 mar 02
Light and dark rutile analyses are shown below. Unlikely that calcining
would make any difference. Main variation is two-fold iron content.
TYPICAL SPECIFICATIONS FOR AUSTRALIAN RUTILE PRODUCTS
Product 1 Product 2 Product 3
TiO2 95.8 96.0 - 96.5 95.50
Fe2O3 0.94 0.50 - 0.80 0.53
ZrO2 0.80 0.50 - 0.80 0.80
SiO2 0.60 0.60 - 0.90 0.90
Cr2O3 0.15 0.18 - 0.28 0.14
Al2O3 0.27 0.30 - 0.80 0.25
P <0.025 n.a. 0.02
MnO 0.01 n.a. n.a.
CaO <0.02 0.01 - 0.06 0.02
MgO 0.02 0.08 - 0.14 0.04
V2O5 0.43 0.58 - 0.65 0.61
Nb2O5 0.34 0.38 - 0.45 0.41
S <0.02 0.01 - 0.025 0.01
SnO2 0.015 n.a. 0.03
Kindly provided by Yolanda Strauss, TZ Minerals International, Perth, W.A.
Michael Banks,
Nelson,
NZ
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