Glass formation followed by in-situ tomography E. Gouillart M.-H. - - PowerPoint PPT Presentation

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Glass formation followed by in-situ tomography E. Gouillart M.-H. - - PowerPoint PPT Presentation

Oct 19, 2023 160 likes •680 views

Glass formation followed by in-situ tomography E. Gouillart M.-H. Chopinet, J. Grynberg, M.J. Toplis Joint Unit CNRS/Saint-Gobain, Aubervilliers (France) Collaborations 1 Why study glass formation ? 2 In-situ tomography 3

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Glass formation followed by in-situ tomography

  • E. Gouillart

M.-H. Chopinet, J. Grynberg, M.J. Toplis Joint Unit CNRS/Saint-Gobain, Aubervilliers (France)

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Collaborations

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1 Why study glass formation ? 2 In-situ tomography 3 Reactions in the Na2CO3 − SiO2 system 4 Evolution of calcium carbonate

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Outline

1 Why study glass formation ? 2 In-situ tomography 3 Reactions in the Na2CO3 − SiO2 system 4 Evolution of calcium carbonate

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Coarse raw materials

  • > slow kinetics

1500°C 1000°C A lot of room for energy saving ?

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Producing homogeneous glass is difficult

Defects Unmolten grains, bubble, chemical gradients... How are they related to the grain sizes, the temperature path, etc. ?

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Literature: TGA in-situ XRD in-situ NMR

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Outline

1 Why study glass formation ? 2 In-situ tomography 3 Reactions in the Na2CO3 − SiO2 system 4 Evolution of calcium carbonate

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Visualizing glass melting from the inside

T = 760◦ C T = 850◦ C T = 799◦ C T = 860◦ C T = 820◦ C T = 877◦ C T = 835◦ C T = 920◦ C

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Faster and faster imaging !

Courtesy Luc Salvo

⇒ huge amounts of (noisy) data to process... O(100Gb) for one experiment

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Absorption and phase contrast

Absorption reconstruction Phase reconstruction (Paganin algorithm, single distance)

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Datasets and issues

In-situ images : speed vs. quality tradeoff. Noisy images, poor contrast, artifacts... Huge datasets : O(1) Go / image × # images in timeseries. Complicated system : what information do we want ?

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Quantitative image processing

Denoising Segmentation of the phases Tracking objects, measuring contacts statistics...

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Outline

1 Why study glass formation ? 2 In-situ tomography 3 Reactions in the Na2CO3 − SiO2 system 4 Evolution of calcium carbonate

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The Na2O − SiO2 system

874 790 830 SiO 2 Na O

2

50 33 66 ... NS NS2 1000 900 800 865: NC melts

Starting from Na2CO3 and not from Na2O : where/how does the system enter the phase diagram ?

T < 865◦ C : solid-state reactions (Turner, Wilburn, ...) Na2CO3 + SiO2 → Na2SiO3 + CO2 Na2SiO3 + SiO2 → Na2Si2O5 T ≥ 865◦ C : reactions between molten Na2CO3 and SiO2.

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Both transformations mechanisms of Na2CO3 can be observed

Reaction in solid and liquid state

Volume fraction of sodium carbonate + crystalline silicates ternary batch, 5 K.min−1 ramp

RT 760 800 840 880

T( ◦ C)

0.00 0.05 0.10 0.15 0.20

c

NS−NS2 Na2CO3 melts

874 790 830 SiO 2 Na O

2

50 33 66 ... NS NS2 1000 900 800 865: NC melts

[Gouillart et al., JACS 2012]

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Both transformations mechanisms of Na2CO3 can be observed

Reaction in solid and liquid state

Volume fraction of sodium carbonate + crystalline silicates ternary batch, 5 K.min−1 ramp

RT 760 800 840 880

T( ◦ C)

0.00 0.05 0.10 0.15 0.20

c

NS−NS2 Na2CO3 melts

874 790 830 SiO 2 Na O

2

50 33 66 ... NS NS2 1000 900 800 865: NC melts

[Gouillart et al., JACS 2012]

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Porous grains with a large specific area

Novacarb sodium carbonate

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Porous grains with a large specific area

Novacarb sodium carbonate

grain

  • pen porosity
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A very reactive system in the solid-state

Formation of crystalline silicates : Na2CO3 + SiO2 → Na2SiO3 + CO2 metasilicate NS Na2SiO3 + SiO2 → Na2Si2O5 disilicate NS2 Solid-state reaction at interspecies contacts 36% Na2CO3, 74% SiO2, 760 ◦C Reaction without contact ? ? 36% Na2CO3, 74% SiO2, 730 ◦C

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Tracking individual grains to learn reaction paths

Sodium carbonate, blue and yellow : two sand grains, white : sodium silicates ⇒ sodium carbonate is extremely reactive and mobile : "semi-local" process

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Reaction in vapor phase

Reaction without contact ? ? Yes ! !

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Reaction in vapor phase

Reaction without contact ? ? Yes ! ! Na2CO3 → ”Na2O” + CO2 K ≪ 1 (10−7)

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Reaction in vapor phase

Reaction without contact ? ? Yes ! ! Na2CO3 → Na2O + CO2 Na2O reacts with silica surface Na2O + SiO2 → Na2SiO3

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Reaction in vapor phase

Reaction without contact ? ? Yes ! ! Na2CO3 → Na2O + CO2 decomposition depends on CO2 partial pressure

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2 different reaction mechanims, depending on the atmosphere

0.00090 0.00095 0.00100

1/T (K−1 )

10-4 10-3 10-2 10-1

v (%NC.s−1 )

MM-N2 MG-N2 MP-N2 PM-N2 MM-CO2

Kinetics of Na2CO3 transformation measured by TGA

  • coll. N. Ferruaud, C. Cazako, S. Papin
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2 different reaction mechanims, depending on the atmosphere

0.00090 0.00095 0.00100

1/T (K−1 )

10-4 10-3 10-2 10-1

v (%NC.s−1 )

MM-N2 MG-N2 MP-N2 PM-N2 MM-CO2

low CO2 partial pressure : vapor-phase reactions are favored Small samples in tomography → CO2 is easily removed.

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2 different reaction mechanims, depending on the atmosphere

0.00090 0.00095 0.00100

1/T (K−1 )

10-4 10-3 10-2 10-1

v (%NC.s−1 )

MM-N2 MG-N2 MP-N2 PM-N2 MM-CO2

high CO2 partial pressure : Na2CO3 decomposes only when in contact with silica.

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Solid-state reactions

800◦ C, 4× speed-up (scans of 2s every 6s)

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Raman + XRD → chemical / crystalline composition of the system

30 60 120

t (min)

25 50 75 100

wt%

Si

liq72-78 liq66-72 liq60-66 NS

4-h plateau at 820◦ C

30 60 120

t (min)

25 50 75 100

wt%

Si

NC NS

NS2

liq liq liq

60-66 66-72 72-78

direct melting at 900◦ C

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Raman + XRD → chemical / crystalline composition of the system

30 60 120

t (min)

25 50 75 100

wt%

Si

liq72-78 liq66-72 liq60-66 NS

4-h plateau at 820◦ C

30 60 120

t (min)

25 50 75 100

wt%

Si

NC NS

NS2

liq liq liq

60-66 66-72 72-78

direct melting at 900◦ C Better homogeneity when solid-state reactions have been favored.

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Raman + XRD → chemical / crystalline composition of the system

30 60 120

t (min)

25 50 75 100

wt%

Si

liq72-78 liq66-72 liq60-66 NS

4-h plateau at 820◦ C

30 60 120

t (min)

25 50 75 100

wt%

Si

NC NS

NS2

liq liq liq

60-66 66-72 72-78

direct melting at 900◦ C Better homogeneity when solid-state reactions have been favored. Can it be explained by the spatial distribution of sodium silicates ?

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Reactions above the melting point of Na2CO3

900◦ C, 4× speed-up (scans of 1s every 6s)

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Outline

1 Why study glass formation ? 2 In-situ tomography 3 Reactions in the Na2CO3 − SiO2 system 4 Evolution of calcium carbonate

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The Na2CO3 − CaCO3 system

20 40 60 80 100 600 700 800 900 1000

Kracek

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The Na2CO3 − CaCO3 system

20 40 60 80 100 600 700 800 900 1000

Kracek Possible formation of a double carbonate Also possible : calcination

  • f CaCO3
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Solid-state reactions between the two carbonates

  • Coll. S. Papin (SGR), G. Matzen, E. Véron (CEMHTI)

Mixture of the two carbonates (50/50) : significant reaction

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Evolution of calcium carbonate in a ternary batch

Two very different reaction paths depending on contacts with sodium carbonate Ternary batch 75%SiO2 13%Na2CO3 12%CaCO3 : < 1 one contact with Na2CO3 for CaCO3 grains (monodisperse grains) Double carbonate path : contacts Na2CO3 - CaCO3 → formation of a crystalline double carbonate. 760 ◦C 25 ◦C 760 ◦C

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Evolution of calcium carbonate in a ternary batch

Two very different reaction paths depending on contacts with sodium carbonate Calcination path : no contacts with Na2CO3 CaCO3 → CaO + CO2 formation of refractory calcium oxide

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A clue for explaining chemical segregation ?

[Chopinet et al., Glass. Tech. 2010]

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Bubbles

Bubbles are created as a result of the production of melts and the deconnexion of the granular network : open pores between grains are closed down by the melts.

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Bubbles

⇒ the initial distribution of bubble sizes is partially determined by the geometry of the granular packing Need for faster acquisitions to follow bubbles creation and evolution.

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Domain coarsening in phase-separating glasses

PhD of David Bouttes

Barium-borosilicate glass Phase-separation in liquid state (1000 - 1400◦ C)

ID19 t = 17 min t = 25 min t = 42 min t = 65 min Evolution of the shape of the domains Hydrodynamical regime

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Conclusions In-situ tomography : a great technique for studying glass melting

Quantitative data on transformations Rich source of inspiration Needs to be coupled with other techniques

The technique is still developing

Towards faster and faster imaging Challenging data processing

Could in-situ tomography be used to study

  • ther systems in glass science ?
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Thank you for your attention !