Manufacture of porous cordierite samples using gelcasting ... · Manufacture of porous cordierite...

I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008

Manufacture of porous cordierite samples using gelcasting of polysaccharides

Isabel Santacruz,1 J.B. Rodrigues Neto,2 R. Moreno1

1 Institute of Ceramics and Glasses, CSIC, Madrid, Spain 2 Sociedade Educacional de Santa Catarina, Joinville, Brazil


Cell Size / nm PROCESSING - Shaping

Microporous <2 Sol-Gel, Sacrificial Templates

Mesoporous 2-50 Sol-Gel, Sacrificial Templates

Macroporous >50 Replica, Sacrificial Templates, Freeze Drying, DIRECT FOAMING

Requirements: a “gel” to fix the structure

INTRODUCTION


Cordierite, 2MgO·2Al2O3·5SiO2

Thermal shock resistance material

High temperature reaction in solid stateSYNTHESIS

Chemical methodsCoprecipitation reactionsSolution combustionSol–gel

INTRODUCTION

Thermal InsulationHoneycomb catalyst supports in automobiles

APPLICATIONS Kiln furnitureFilters


OBJECTIVE

Direct Foaming

Gelcasting of polysaccharides

Cordierite Materials with Tailored Porosity

Colloidal Processing


EXPERIMENTAL

Cordierite, 2MgO·2Al2O3·5SiO2

Raw Materials

100:0, 85:15, 15:85

Ss 0.7 m2/gd50 5.7 µmρ 3.98 g/cm3

CL3000FG1000SGSs 10.2 m2/gd50 0.6 µmρ 3.98 g/cm3

Alumina, 16.2 wt%

500 nm

ALCOA, USA

Talc, 43.8 wt% Kaolin, 40.0 wt%

Colorminas S.A., Criciúma, Brazil

Ss 20.6 m2/gρ 2.76 g/cm3

Ss 9.5 m2/gρ 2.58 g/cm3

MgO, Al2O3, SiO2molar ratio: 22.2 / 22.2 / 55.6 weight ratio: 13.8 / 34.9 / 51.3


Raw Materials

Suspension

Water, % Dolapix PCN (Zschimmer-Schwarz, Germany), pH, fine and coarse alumina, ageing...

Dense

Slip castingSintering

Residual Porosity

Slip castingSintering

Milling(t planetary mill, 15-45 min)

500 nm

EXPERIMENTAL

Porous samples

Direct Foaming / Polysaccharides

Sintering

ReplicaSintering

SPONGE IMPREGNATION

P


Powders Mixture Water + Dolapix PCN (1.5 wt%)

45 min Milling, pH 11

High shear mixing, t = 3 min

CastingCoolingGelation

DryingFiring

Heating, 65ºC 1.0 wt% Agar (sol. 6 wt%) - Gel former

1.0 wt% DDB-Surfactant-Foamer

Final Sample

Direct Foaming (Polysaccharides)

EXPERIMENTAL

COOLING60°C

Gel-casting

Dodecylbenzene (DDB)dodecylbenzenic acid + NH4OH DDB

20 g 20 ml / 80 ml H2O


24 h48 h

0 h72 h

0 200 400 600 800 10000

50

100

150

200

She

ar S

tress

(Pa)

Shear Rate 1/s)

0h 24h 48h 72h

Ageing24 h48 h

0 h72 h

0 200 400 600 800 10000

50

100

150

200

She

ar S

tress

(Pa)

Shear Rate 1/s)

0h 24h 48h 72h

24 h48 h

0 h72 h

0 200 400 600 800 10000

50

100

150

200

She

ar S

tress

(Pa)

Shear Rate 1/s)

0h 24h 48h 72h

0 200 400 600 800 10000

50

100

150

200

She

ar S

tress

(Pa)

Shear Rate 1/s)

0h 24h 48h 72h

Ageing

SUSPENSION, 40 vol%Dolapix content

1.5 wt% Dolapix PCN

pH = 11

Al2O3 fine / Al2O3 coarse85 / 15

Stable!

1.5 wt%2.0 wt%1.0 wt%0.75 wt%

0 100 200 300 400 5000

50

100

150

200

250

300

Shea

r Stre

ss (P

a)

Shear Rate (1/s)

0.75% DolapixPCN 1.0% DolapixPCN 1.5% DolapixPCN 2.0% DolapixPCN

1.5 wt%2.0 wt%1.0 wt%0.75 wt%

0 100 200 300 400 5000

50

100

150

200

250

300

Shea

r Stre

ss (P

a)

Shear Rate (1/s)


0 100 200 300 400 5000

50

100

150

200

250

300

Shea

r Stre

ss (P

a)

Shear Rate (1/s)


15/85

100/0

85/15

0 200 400 600 800 10000

50

100

150

200

250

300

350

400

Shea

r Stre

ss (P

a)

Shear Rate (1/S)

100% A1000SG 85% A1000SG+15% A3000FG 15% A1000SG+85% A3000FG

Al2O3: fine (0.6 µm) / coarse (5.7 µm )

15/85

100/0

85/15

0 200 400 600 800 10000

50

100

150

200

250

300

350

400

Shea

r Stre

ss (P

a)

Shear Rate (1/S)


15/85

100/0

85/15

0 200 400 600 800 10000

50

100

150

200

250

300

350

400

Shea

r Stre

ss (P

a)

Shear Rate (1/S)


0 200 400 600 800 10000

50

100

150

200

250

300

350

400

Shea

r Stre

ss (P

a)

Shear Rate (1/S)


Al2O3: fine (0.6 µm) / coarse (5.7 µm )

pH 11pH 10pH 9pH 8pH 7

0 200 400 600 800 10000

50

100

150

200

250

300

350

400

Shea

r Stre

ss (P

a)

Shear Rate (1/s)

pH=7.0 pH=8.3 pH=9.0 pH=10.0 pH=11.0

pH

pH 11pH 10pH 9pH 8pH 7

0 200 400 600 800 10000

50

100

150

200

250

300

350

400

Shea

r Stre

ss (P

a)

Shear Rate (1/s)

pH=7.0 pH=8.3 pH=9.0 pH=10.0 pH=11.0

pH


MILLING

Size distribution

Milled - 45 min

Unmilled

Krieger-Dougherty

Milled45 min

Unmilled

0,0 0,1 0,2 0,3 0,4 0,51E-3

0,01

0,1

1

10

η ∞ (P

a.s)

φ

η∞/P

as

Φ

Milled45 min

Unmilled

0,0 0,1 0,2 0,3 0,4 0,51E-3

0,01

0,1

1

10

η ∞ (P

a.s)

φ

η∞/P

as

Φ0,0 0,1 0,2 0,3 0,4 0,5

1E-3

0,01

0,1

1

10

η ∞ (P

a.s)

φ

η∞/P

as

Φ0,1 1 10 100

Freq

uenc

y

Particle Diameter (µm)

Unmilled 45 min 45 min - pH=11.0

Particle Diameter / µm

Vol

ume

/ %

0,1 1 10 100

Freq

uenc

y

Particle Diameter (µm)

Unmilled 45 min 45 min - pH=11.0

Particle Diameter / µm

Vol

ume

/ %


DYNAMIC SINTERING STUDIES

Milled - 45 min

Unmilled

Dilatometry

1250ºC / 1 h 1300ºC / 1 h 1350ºC / 1 h 1400ºC / 1 h

-10

-8

-6

-4

-2

0

2

0 200 400 600 800 1000 1200 1400Temperature / ºC

L/Lo

(%)


RESIDUAL POROSITY2.2 g cm-3

DENSE2.6 g cm-3

STATIC SINTERING, XRD

T < 1300ºC: Cordierite is not yet the major phase

1300ºC

1200 1250 1300 1350 14002,0

2,2

2,4

2,6

2,8

3,0ρ

(g/c

m3 )

Temperature (ºC)

Milled 45 min Without mill

Temperature / ºC

ρ/ g

/cm

3

1300ºCC

CCC/Cr

CCC

CC Milled - 45 min

CC

CC/Cr

CCC

CC Unmilled

Q Q

Milled - 45 min

Unmilled


CONTROLLED POROSITY

Dense

Porous samples

Direct Foaming / Polysaccharides

Replica

Replica

Milled - 45 min

Direct Foaming

Parameters

Solids Loading Temperature

Viscosity!! “Gelling time”


DIRECT FOAMING

Viscosity / mPa s

45 vol% 190 - 22030 vol% 160 - 17020 vol% 10 - 15

Milled Suspension + +Gelling agent + Foaming agent

20 30 50 6040

0.80.60.40.2

1.0

0.0

Visc

osity

/ Pa

s

Temperature / ºC

20 vol%

45 vol%

30 vol%

45ºC40ºC 65ºC100 s-1

20 30 50 6040

0.80.60.40.2

1.0

0.0

Visc

osity

/ Pa

s

Temperature / ºC

20 vol%

45 vol%

30 vol%

45ºC40ºC 65ºC100 s-1100 s-1

Solids Loading Temperature

Viscosity!! “Gelling time”


T = 65ºC

20 vol% 30 vol% 45 vol%

DIRECT FOAMING

125 µm 40 µm90 µmAverage celldiameter


20v-45C

20 vol%

T = 40ºC

DIRECT FOAMING

T = 65ºCT = 45ºC


DIRECT FOAMING

186

221

159

162

170

10

13

15

Viscosityat 100 s-1

mPa s

1.22.045 vol%-65ºC

1.81.945 vol%-45ºC

29.41.530 vol%-65ºC

18.41.730 vol%-45ºC

15.11.830 vol%-40ºC

76.50.620 vol%-65ºC

74.00.720 vol%-45ºC

73.90.620 vol%-40ºC

Open porosity

Vol%

Apparent density

±0.1 g cm-3SAMPLE

125 µm

40 µm

90 µm

Average celldiameter


SUMMARY- Homogeneous aqueous suspensions of kaolin/talc/alumina mixture have been prepared: 1.5 wt% Dolapix PCN, 85/15 fine/coarse aluminas and pH 11. The effect of the milling was studied.

- Sintered unmilled samples showed large remain porosity, but milled ones lead to dense structures due to the activation of the raw materials by milling.

- Cordierite phase only appears as main phase at T ≥ 1300ºC.

- Materials with tailored porosity have been prepared from milled suspensions by sponge impregnation and by Direct Foaming (gelcasting of polysaccharides in combination with a foaming agent).

-The solid loading of the precursor slip is a critical parameter in the manufacture of porous samples by Direct Foaming which is related to the slips viscosity.

Porous CoatingsWork in elaboration!!


THANK YOU VERY MUCH FOR YOUR ATTENTION!

Manufacture of porous cordierite samples using gelcasting ... · Manufacture of porous cordierite...

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