Emissions from melted glass:
experimental and theoretical
approaches
MAKAROV Pavel
2st year master student MSU
Trainee in SGR: 18/03/2013 – 31/07/2013
Supervisors: BLAHUTA Samuel
CONDOLF Cyril
INTRODUCTION
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Key questions
What gaseous species are the most stable during volatilization
of glass in Na-B-Si-O(-H) system according to literature data?
What thermochemical databases do we have?
Are current databases convenient for simulation of
experimental processes?
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Summary of presentation
Literature survey on the most stable gaseous species in
high temperature (1700 – 1800 K) region;
1
Volatilization experiments (binary, ternary glasses);
2
Thermodynamic simulation (FactSage) of the experiments;
3
Comparison of experimental results to FactSage simulation;
4
NaBO2, HBO2 (+NaOH)
General conclusions;
Perspectives.
4
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NaBO2 (g): literature data, comparison to FactSage
NaBO2 (g) partial pressure
(log)
(1)
Cole et
al., 1935
Cable et al.,
1987
Gorokhov et
al., 1971
Nalini et
al., 2008
Ivanov,
2002
1000/T, K-1
• Data for NaBO2 (g) were modified (based on FactPS data);
Poor agreement of FactPS and experimental data
• New database FactTEST was created;
In high temperature region
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(1) How to build new database?
NaBO2 (l) ↔ NaBO2 (g)
1) Thermodynamic description
∆G = G(NaBO2(g)) – G(NaBO2(l)) = - RT lnKeq
Keq = P(NaBO2(g))/a(NaBO2(l))
a(NaBO2(l))=1
_____________________________________
∆G = G(NaBO2(g)) – G(NaBO2(l))= - RT lnP(NaBO2(g))
2) Experimental description
lg P = A + B/T
?
FactSage
(SLAGA)
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Literature data
6
(1)
NaBO2 (g): literature data, comparison to FactSage
NaBO2 (g) partial pressure
(log)
2 B2O3 + Na2O
Cole et
al., 1935
1000/T, K-1
FactTEST is also efficient for Na2O/B2O3 system with
different compositions
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7
(1) HBO2 (g): literature data, comparison to FactSage
1000/T, K-1
HBO2 (g) partial pressure
(log)
B2O3(s) + H2O(g):
1960
FactPS: Good agreement to Knudsen effusion massspectrometric method data;
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8
(1) HBO2 (g): literature data, comparison to FactSage
Equilibrium constant
(log)
B2O3 (l) + H2O (g) = 2 HBO2 (g)
T, K
FactPS: Good agreement for values obtained from
transpiration method;
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9
(1) HBO2 (g): literature data, comparison to FactSage
0.5 H2O (g) + 0.5 B2O3 (l or s) = HBO2 (g)
FactPS calculation results in agreement with experimental
(Knudsen effusion method) at different T;
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10
(1) Conclusions on thermodynamic databases?
thermodynamic functions for NaBO2 (g) modified;
 new database (FactTEST);
thermodynamic functions for HBO2 (g) – no change;
 still using FactPS.
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Summary of presentation
Literature survey on the most stable gaseous species in
high temperature (1700 – 1800 K) region;
Volatilization experiments (binary, ternary glasses);
2
Thermodynamic simulation (FactSage) of the experiments;
3
Comparison of experimental results to FactSage simulation;
4
General conclusions;
Perspectives.
12
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(2) Experimental set-up
Conditions: T = 1475 °C, P(H2O) = 0,19 & 0,65 bar;
Glass: 1) binary (26 wt. % Na2O, 74 wt. % SiO2);
2) ternary (26 wt. % Na2O, 5 wt. % B2O3, 69 wt. % SiO2);
Quartz fiber filter
Flacons with deionized water
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(2) What changes during the experiment?
Initial
composition
of glass
5 series of solutions for each hour was analyzed with ICP
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(2) Analyses used, sample preparation
ICP (for all solutions);
pH – measurments;
μprobe analyses;
SEM/EDS (additional);
Ci in
each
solution
Gas / melt composition
on each step
Verification of ICP &
μprobe
Final glass
composition,
concentration profiles
Verification μprobe
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Summary of presentation
Literature survey on the most stable gaseous species in
high temperature (1700 – 1800 K) region;
Volatilization experiments (binary, ternary glasses);
Thermodynamic simulation (FactSage) of the experiments;
3
Comparson of experimental results to FactSage simulation;
4
General conclusions;
Perspectives.
16
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(3) Thermodynamic simulation (FactSage) of
volatilization experiments
Qi = ΣQ(i elem)
ICP output
Input for
FactSage
FactSage
simulation
comparison
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(3) Ternary glass: working assumption
ICP: Ci
in each
solution
Pj we
want to
calculate
Na
NaBO2
B
HBO2
ICP result recalculation: Main assumption - NaOH amount is negligible
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Summary of presentation
Literature survey on the most stable gaseous species in
high temperature (1700 – 1800 K) region;
Volatilization experiments (binary, ternary glasses);
Thermodynamic simulation (FactSage) of the experiments;
Comparison of experimental results to FactSage simulation;
4
General conclusions;
Perspectives.
19
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Na, Si
(4) Binary glass: experiment vs FactSage
Time ↑
0,65 bar
NaOH (g) partial pressure (log)
NaOH (g) partial pressure (log)
0,19 bar
Time ↑
FactSage simulation results are close to experimental points
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20
Na, Si
(4) Binary glass: experiment vs FactSage
μprobe
P (H2O)
SiO2,
wt. %
Na2O,
wt. %
0.19 bar
73.2
16.8
0.65 bar
73.6
17.4
SiO2
µprobe
ICP
Na2O
1) Flat profiles (µprobe) → it’s possible to recalculate melt
composition from ICP results;
2) Differs between w(Na2O) for ICP and for µprobe.
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21
Na, Si
EDS
(4) Binary glass: experiment vs FactSage
Na
BlackGlass
particles
matrix
?
O
Si
1) Precipitation during cooling of melt;
2) Precipitate absorbs Na from glass matrix.
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22
Na, Si, B
(4) Ternary glass: experiment vs FactSage
T = 1475 °C
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Na, Si, B
(4) Ternary glass: experiment vs FactSage
ICP analysis
FactTEST is not suitable because of problems with mass balance at phase
equilibrium calculation (reason – G(T) for NaBO2 (g) in FactTEST)
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Na, Si, B
(4) Ternary glass: experiment vs FactSage
Cross section plotting
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Na, Si, B
(4) Ternary glass: experiment vs FactSage
NaBO2
HBO2
1) FactPS results are in agreement with ICP for NaBO2 (g);
2) Differs for HBO2 (g) at 0,65 bar:
Possible reasons: - not all condensate was collected in experiments;
- deffects of thermodynamic glass model in FactSage.26
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Na, Si, B
(4) Ternary glass: experiment vs FactSage
μprobe
P
(H2O)
SiO2,
wt. %
B2O3,
wt. %
0.19
bar
72,9
1,6
19,8
0.65
bar
73,2
1,6
20,9
Na2O,
wt. %
SiO2
ICP
µprobe
B2O3
Na2O
1) Flat profiles (µprobe);
2) Differs (less than for binary glass) between w(Na2O) for ICP and for
µprobe.
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Na, Si, B
(4) Ternary glass: experiment vs FactSage
EDS
Black particles
Glass matrix
Na
O
Si
1) Precipitation during cooling of melt;
2) Precipitate absorbs Na from glass matrix.
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(4) Industrial glass (SGR, 2009)
Insulation glass (wt. %):
SiO2 = 65.6
Al2O3 = 2
B2O3=4.3
CaO=8
MgO=2.7
Na2O (+K2O)=17.0 (K2O=0.6 put as Na2O)
T = 1475 °C, P(H2O) = 0,19 bar
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(4) Industrial glass (SGR, 2009)
1) FactPS can be approached for experiment simulation;
2) FactTEST is not suitable.
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(4) Industrial glass (SGR, 2009)
NaBO2
HBO2
The same magnitudes for Pi like in our experiments → Differs for HBO2 (g)
for ternary glass at 0,65 bar could be explained by problems of
theoretical glass model in FactSage;
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Summary of presentation
Literature survey on the most stable gaseous species in
high temperature (1700 – 1800 K) region;
Volatilization experiments (binary, ternary glasses);
Thermodynamic simulation (FactSage) of the experiments;
Comparison of experimental results to FactSage simulation;
General conclusions;
Perspectives.
32
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General conclusions
According to literature analysis:
- Thermodynamic properties of NaBO2 (g) in FactPS were
modified;
- New FactTEST database was created;
- Properties of HBO2 (g) are in good agreement with literature
data;
Volatilization experiments were carried out;
FactTEST can not be used for real experiment simulation;
Initial database FactPS was recommended to be used for experiment
optimizing.
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PERSPECTIVES
NaBO2 (g) partial pressure
(log)
Verification of Tboiling of pure NaBO2 (g) (literature – 1434°C, FactPS –
1757°C);
1434°C
1757°C
1000/T, K-1
Check SLAG database on data correctness, creating new database/
new solution model for glass melt in Na2O-B2O3-SiO2 system;
34
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