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Glass-ceramics: developement of commercial materials

Monique Comte USTV, Orléans (France) Nov. 5, 2009 Different products

NEG website

Eurokera website

Neoparies – Hexingtai Stone Materials website IlIvoclar - Viva den t website Science & Technology © Corning Incorporated 2009 Introduction: what is a glass-ceramic ?

• A matérial – Melted and formed as glass article – Partially crystallized by a further thermal treatment (nucleation and growth)

• Accordinggy to the nature of the crystals and to microstructure, obtention of materials with unique properties

• Crystallization increases the viscosity of the material and its resistance to temperature.

Science & Technology © Corning Incorporated 2009 Controlled crystallization

Kerawhite® Macor® (spodumene g.c) (Micas g.c)

Science & Technology © Corning Incorporated 2009 Introduction: what is a glass-ceramic ?

• A matérial – Melted and formed as glass article – Partially crystallized by a further thermal treatment (nucleation and growth)

• Accordinggy to the nature of the crystals and to microstructure, obtention of materials with unique properties

• Crystallization increases the viscosity of the material and its resistance to temperature.

Science & Technology © Corning Incorporated 2009 Nucleation • For most glasses – Homogeneous nucleation is difficult – Crystallization develops from surface or defects

• Two kinds of glass-ceramics – From glass frit: sintering and crystallization(surface nucleation) – From bulk: heterogeneous nucleation (nucleating agents)

Science & Technology © Corning Incorporated 2009 Glass-ceramic formation by surface nucleation

L.R. Pinckney – Corning

Science & Technology © Corning Incorporated 2009 Example: Cordierite glass-ceramics for electronic packaging Interests (()vs Alumina): - lower dielectric constant - Possible cofiring with Cu below 1000°C

C(t%)Compos (wt%)

SiO2 50 – 55

Al2O3 18 - 23

MgO 18 - 25 12

B2O3+P2O5 0 - 6 iscosity (P) VV 7 Crystallization -6 -1 CTE 3 x10 K Nucleation and Main phase: Sintering binder burn off -cordierite (25-200°C) 3 700 800 900 1000 Dielectric 5 Temperature (°C) cst R. Tummala J. Am. Ceram. Soc 74 (1991) 895

Science & Technology © Corning Incorporated 2009 Glass-ceramic formation by internal nucleation

L.R. Pinckney – Corning

Science & Technology © Corning Incorporated 2009 Heterogeneous nucleation

Examples of Effect nucleating agents

TiO2, ZrO2 • Efficient in a lot of aluminosilicate glasses Fluorine • Crystallization of fluorine bearing phases (apatite, micas, amphiboles.. ) Metal colloids • Nucleate lithium silicate (Ag, Pt, Au .. ) (via UV irradiation)

Favors • Phase separation • Precipitation of a first crystalline phase which acts as a nucleant

Science & Technology © Corning Incorporated 2009 1 A few specific properties of bulk glass-ceramics • Formation of metastable phases – Crystallization at high degree of supercooling favors formation of metastable phase – At higher temperature they transform to a stable assemblage – These phases could have unique properties • Possibility to obtain transparent materials • Wide range of CTE: – -40 to 120 x10-7K-1 • Wide range of mechanical strength • Refractory materials

Science & Technology © Corning Incorporated 2009 1 Crack propagation in glass-ceramics Examples

Cristalline phase Leucite Disilicate de Li (K2O-Al2O3-4SiO2) % of crystals 30% 60% 1/2 KIC (MPam ) 111,1 272,7

E. Apel et al. J of mechanical behaviour of biomedical mat. I (2008) 313-325

Science & Technology © Corning Incorporated 2009 1 Examples

Nucleatinggg agents Cryypstalline phases Main ppproperties B-quartz Transparent B-spodumene Zero-expansion Spinel Transparent TiO2, ZrO2 High strain point Cordierite +… Refractory Feldspar +… Ag0 Li sili ca te Phot osensiti ve Li disilicate F Micas Machinable

B-quartz, Li silicate: metastable phases

Science & Technology © Corning Incorporated 2009 1 Design of commercial glass-ceramics:

Requirements

Set of product Phase assemblage and microstructure properties Glass melting Compatiblity with furnaces operations Glass forming Low enough liquidus (low temperature / high viscosity)

Glass-ceramic • « Short » thermal treatment length (hours) formation • Control of the shape of the glass article

Science & Technology © Corning Incorporated 2009 1 LAS glass-ceramic: Transparent and zero-expansion material

Solid solution: AditthAccording to the compos ition Li2-2(x+y)MgxZnyO.Al2O3.nSiO2 expansion strongly varies n: 2 to 10 (-50 to +50 x10-7K-1) (6 to 8 in commercial products)

Glass-ceramic technology : W. Höland and G. Beall Am. ceram. Soc (2002) Science & Technology © Corning Incorporated 2009 1 LAS glass-ceramic Typical composition range for parent glass

• SiO2 : 55 - 70 (wt%) • Al2O3 : 15 - 27 • Li2O : 1 - 5 • MgO : 0 - 4 • ZO0ZnO: 0 - 4

• TiO2 + ZrO2 : 2 – 5 (nucleating agents) • Other: 0 - 5 (fining agents, coloring oxides… )

• Possible to taylor properties (expansion, transparency) playing on compositions and microstructure.

Science & Technology © Corning Incorporated 2009 1 Crystallization sequence

1600 Glass melting 1400 and forming

1200

1000 e (°C) rr 800

600 emperatu TT NlNanoscale 400 phase separation 200

0 0 200 Time

Science & Technology © Corning Incorporated 2009 1 Crystallization sequence

1600 Glass melting 1400 and forming

1200

1000 e (°C) rr 800 Nucleation: TiZrO4 formation 600 emperatu TT

400 TEM. T. Douillard, 200 INSA Lyon

0 GEMPPM 0 200 Time

Science & Technology © Corning Incorporated 2009 1 Crystallization sequence

1600 Glass melting 1400 and forming

1200 -quartz formation 1000

e (°C) and growth rr 800 Nucleation: TiZrO4 formation 600 emperatu TT NlNanoscale 400 phase separation TEM. 200 T. Douillard, INSA Lyon GEMPPM

0 0 200 Time

Science & Technology © Corning Incorporated 2009 1 Crystallization sequence

1600 Glass melting Transformation 1400 and forming to spodumene 1200 + minor phases -quartz formation 1000

e (°C) and growth rr 800 Nucleation: TiZrO4 formation 600 emperatu TT NlNanoscale 400 phase separation TEM. 200 T. Douillard, INSA Lyon GEMPPM

0 0 200 Time

Science & Technology © Corning Incorporated 2009 2 LAS glass-ceramics (manufactured by Eurokera) Microstructure

Kerablack ® Kerawhite ® Main crystalline phase quartz spodumene Mean cryy()stallite size (XRD) 70 nm 160 nm

Other crystalline phases (< 5wt%) TiZrO4 (2,5 nm) TiZrO4 (2,5 nm) (mean crystal size) quartz, Spinel Residual glass: wt% Around 15%

Microstructure (SEM)

Science & Technology © Corning Incorporated 2009 2 LAS glass-ceramic (manufactured by Eurokera) Properties

100 Transparent CTE 90 Colorless 80 0-700°C (10-7K-1) 70 Transparent ® 60 Black Kerablack -1 ion (%) Opalescent/opaque ss ® 50 Keralite 1 ® 40 Kerawhite 10

Transmis 30 Kerablack 20 Keralite 10 Kerawhite

0 300 600 900 1200 1500 1800 2100 2400 Wavelength (nm)

Science & Technology © Corning Incorporated 2009 2 Crystallization of a LAS glass-ceramic Stu die d by in s itu HT XRD • Experimental: – Anton Paar HTK 1200 furnace (max. temp.: 1200°C) – TT: 30°C/min up to 660°C 3.5°C/min from 660 to 1100°C – Diffractometer: Panalytical X'Pert Pro with a q/2q Bragg Brentano geometry – Cu monochromatic configuration – PIXel solid -state didetector in scann iding mode was use d. Acquisition times: 3min – Used of Fullprof program to performe Rietveld Refinement Analysis (JJodge. Rodrigez-Carv ajal , Commi ssi on on pow der diff. Neeswsl (2001)26,12) Science & Technology © Corning Incorporated 2009 2 Crystallization of a LAS glass-ceramic: Amount of cryypstalline phases vs tem perature

100 of

tt 90 80 70

r (wt%) srilankite e/amoun ee ss 60 beta-quartz 50 beta-spodumene ach pha zed matt zed 40 ii ee 30 20 crystall ount of

mm 10 A 0 800 900 1000 1100 Temperature (°C)

Science & Technology © Corning Incorporated 2009 2 Crys ta llizati on of a LAS g lass-ceramic

-quartz amount and mean crystallite size vs temperature

110 11,00 100 10,00 90 9,00 80 8,00 exp4) allite size allite tt 70 7,00 00 60 6,00 (nm)

artz crys 50 5,00 factor (x1 factor uu 40 4,00

30 3,00 Scale

Mean b-q Mean 20 Mean crysallite size (nm) 2002,00 Scale factor (X10exp4) 10 1,00 800 840 880 920 960 1000 1040 1080 Tt(°C)Temperature (°C)

Science & Technology © Corning Incorporated 2009 2 Crys ta llizati on of a LAS g lass-ceramic Variation of composition of b-quartz solid solution with

temperature (Li2-2(x+y)MgxZnyO.Al2O3.nSiO2) 7,00

6,50

n 6,00

5,50 spodumene begins to form.

5,00 800 850 900 950 1000 1050 Temperature (°C)

Science & Technology © Corning Incorporated 2009 2 (Z, M)AS glass-ceramic

• Composition: SiO2-Al2O3-ZnO-MgO-TiO2-ZrO2

• Phase assemblage: Crystals of spinel (Zn,Mg)Al2O4 in a continuous matrix of silica –rich glass • Microstructure: uniformly dispersed, 10-20 nm crystals

Transparent material

L.R. Pinckney J.of non-Cryst. Sol. 255(1999)171

Sppginel glass- Vitreous Code 1737 ceramic silica

CTE (25 -300°C) (x 10-7K- 37 6 38 1) 945°C 990-1090°C 666°C Strain point 98 72 73 Young modulus (GPa) 650 500 460 Knoop hardness (KHN100) 73 60 56 MOR (MPa)

1- MgO-Al2O3-SiO2-TiO2 system

SiO2 (()wt%) 43,8

Al2O3 24,7 MgO 18,7 COCaO 141,4

TiO2 11,4

Heat treatment 825°C/ 2h 1200°C/ 10h Indialite CTE (25 - 41 x 10-7K-1 Enstatite Mg2Al4Si5O18 1000°C°) 130 GPa MgSiO3 Low CTE Karroite Lamellar E modulus 165 +/- 6MPa6 MPa MgTi2O5 titwinni ng Abraded MOR 4.3 +/- 0.4 MPa m0.5 High E K1C 984 +/- 16 G.H. Beall, J. Europ. Ceram. KHn 1250°C Soc. 29(2009)1211 Thermal stability Science & Technology © Corning Incorporated 2009 2 Refractory glass-ceramics

2- SrO-Al2O3-SiO2-TiO2 system

SiO2 (()wt%) 34.1

Al2O3 32.9 SrO 23.9

TiO2 919.1

Heat treatment 850°C/ 2h 1425°C/ 6h CTE 43 x10-7K-1 (25-1000°C°) Abraded MOR 132 +/- 17 MPa Sr-feldspar SrAl2Si2O8 (MPa) + Tielite (Al2TiO5) 0.5 K1C (MPa m ) 2.67 +/- 0.2 Thermal stability 1450°C G.H. Beall, J. Europ. Ceram. Soc. 29(2009)1211 Science & Technology © Corning Incorporated 2009 3 Refractory glass-ceramics

• Alkaline-earth aluminosilicates

• Internally nucleated with TiO2 • Maximum use temperature: 1200-1500°C range • Potential applications: – Improved radomes – Enggpine components – Substrates for semi-conductors – Precision metallurgical molds

Science & Technology © Corning Incorporated 2009 3 Metal colloids used as nucleating agents: Photosensitive glass-ceramics • FOTOFORM® /FOTOCERAM® or FOTURAN®

• Use: Etched patterned materials

• Composition:

– SiO2 : 80 % wt

Al2O3 : 4

Li2O: 10 others: 6 – Nucleating agent: Ag0 (with Ce3+)

Mask UV Ce3+ + Ag+ Ce4+ + Ag0

Formation of Ag0 colloids

T.T. : 500-600°C

Cryst alli zati on : Li 2O-SiO2

3 Chemical etching (HF 10%)

UV + T.T. : 600-700°C Dendritic crystallization of Li2O-SiO2

Crystallization : Li2O-2SiO2

• Use: fabrication of high-precison components Smallest structures: 25 µµpm are possible with a rou ghness of 1 µm. • Use: micro-mechanics, micro-optics, fluid devices…

Microreactor Mikroglas website

Example Macor

SiO2 47,2 Al2O3 16,7 B2O3 858,5 MgO 14,5 K2O 9,5 F 6,3

From Glass-ceramic technology : W. Höland and G. Beall (Am. ceram. Soc (2002))

Science & Technology © Corning Incorporated 2009 3 Conclusion • Glass-ceramics are very versatile materials (even if the developement of commercial materials can be tough)

• Development of new materials would benefit from a better understanding of crystallization (especially nucleation) mechanisms. • The recent advances in glass structural studies (via solid state NMR, SAXS, X-Ray diffraction and absorption…) would allow significant progresses in this area.