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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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
OBJECTIVE
Direct Foaming
Gelcasting of polysaccharides
Cordierite Materials with Tailored Porosity
Colloidal Processing
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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)
0.75% DolapixPCN 1.0% DolapixPCN 1.5% DolapixPCN 2.0% DolapixPCN
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
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)
100% A1000SG 85% A1000SG+15% A3000FG 15% A1000SG+85% A3000FG
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
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 )
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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
/ %
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
(%)
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
CONTROLLED POROSITY
Dense
Porous samples
Direct Foaming / Polysaccharides
Replica
Replica
Milled - 45 min
Direct Foaming
Parameters
Solids Loading Temperature
Viscosity!! “Gelling time”
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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”
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
T = 65ºC
20 vol% 30 vol% 45 vol%
DIRECT FOAMING
125 µm 40 µm90 µmAverage celldiameter
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
20v-45C
20 vol%
T = 40ºC
DIRECT FOAMING
T = 65ºCT = 45ºC
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
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!!
I. Santacruzi-SUP2008, Innovation for Sustainable Production 2008
THANK YOU VERY MUCH FOR YOUR ATTENTION!