OPTOCERAMICS Pille, A., Kanaev, A., Chateigner, D., El Mendili, Y., - - PowerPoint PPT Presentation

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OPTOCERAMICS Pille, A., Kanaev, A., Chateigner, D., El Mendili, Y., - - PowerPoint PPT Presentation

Nov 13, 2023 228 likes •357 views

Texte FROM WET SPONGES TO OPTOCERAMICS Pille, A., Kanaev, A., Chateigner, D., El Mendili, Y., Feldbach, E., Billeton, T., Schoenstein, F. Laboratoire de Sciences des Procds et des Materiaux, Universit Paris 13, Sorbonne Paris Cit,

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SLIDE 1

Texte

ECerS 2017 Budapest

FROM WET SPONGES TO OPTOCERAMICS

Pille, A., Kanaev, A., Chateigner, D., El Mendili, Y., Feldbach, E., Billeton, T., Schoenstein, F.

Laboratoire de Sciences des Procédés et des Materiaux, Université Paris 13, Sorbonne Paris Cité, Villetaneuse, France, e-mail: annika.pille@lspm.cnrs.fr

T02: High Temperature Processes and Advanced Sintering

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Topics of discussion

  • Context and objective
  • Growing and modifying the “sponges”
  • Consolidation – spark plasma sintering
  • Characterization of ceramics
  • Conclusions and perspectives

Porous sponges SPS Micro- grained ceramics

bottom-up strategy

11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 2

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Motivation

To control the grain size of ceramics on our way to self-healing nano-grained transparent ceramics Applications as optical windows in nuclear (fusion) power plants, transparent armors, nose cones for heat seeking missiles (YAG), space engineering, medicine …

11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 3

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SLIDE 4

Growing alumina monoliths*

TMES

*Vignes, J. L. et al. J. Mater. Sci. 43 (2008) **Khatim, O. et al. Acta Materialia 71 (2014) 11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 4

1 cm/h = 0,5 g (43 m% water) 80% humidity, 25°C, cooling plate 23°C Al plate + Ag-Hg amalgam -> Al(OH)3 monolith

UPA

99% porosity of the monolith makes it easy to dope by gas

  • r liquid

**

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SLIDE 5

Spark plasma sintering

  • Vacuum or argon
  • Conductive or not
  • 3.5 – 50 kN
  • 20 – 2000°C
  • Sample

displacement

  • Dr. Sinter LAB Series SPS-515S

11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 5

  • Joule effect

=> fast process, grain size control

  • High temp + pressure

=> dense materials

600 1200 1800 2400 3000 3600 4200 4800 5400

  • 7
  • 6
  • 5
  • 4
  • 3
  • 2
  • 1

Displacement (mm) Time (s)

C1 displacement 600 1200 1800 2400 3000 3600 4200 4800 5400 20 30 40 50 60 70 80

Pressure (MPa)

C1 pressure

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SLIDE 6

Alumina ceramics

11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 6

2 um

commercial 𝛿-alumina 𝛓=97,8%

1450°C 20’ + 1150°C 10’ @ 80 MPa

From previous work in LSPM*

1450°C 20’ @ 80 MPa

  • ur 𝛿-alumina

𝛓≈ 100%

*Tõldsepp, E. et al. Ceram. Int. 42 (2016)

Although our 𝛿-alumina powder crystallite size is smaller than the commercial powder’s, the sintered ceramic has bigger grain size

Powder crystallite size: 10 nm Powder crystallite size: 50 nm

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SLIDE 7

11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 7

2 um

  • ur alumina, no pre-pressing

𝛓=96,6%

Effect of green body preparation

20 um

  • ur alumina, pre-pressing with 4t

𝛓=98,6% SPS cycle: 3’ at 1450°C, 300 MPa

Pre-pressing with 4t for better densification leads to a tenfold increase in grain size

1 um

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SLIDE 8

XRD texture study

5° ×5° grid with 0°≤ χ ≤55° and 0°≤ ϕ ≤ 355° 11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 8

As received from SPS Post-annealing at 1000°C

  • Mild fibrous texture aligned with SPS pressure-axis
  • Crystallite shape “spherifizes” during annealing
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SLIDE 9

11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 9

2 um

commercial spinel

𝛓=96,5% 𝛓=97,3%

10 um

  • ur alumina + Mg(NO3)2

2 um

  • ur alumina + TMES

𝛓=3,54 g/cm3

Mullite, spinel – reactive sintering

SPS cycle: 20’ at 1450°C + 10’ at 1150°C, 100 MPa Our alumina doped with TMES in gas phase OR in liquid phase with Mg(NO3)2∙6H2O

  • Stoichiometric Al2O3:MgO ratio gives monophasic spinel ceramic
  • Average grain size of spinel produced by reactive sintering is about 5 times

larger than that of spinel produced from commercial powder via the same cycle.

2 um 1 um

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SLIDE 10

Cathodoluminescence study

  • 1.8 eV -> the R-lines of Cr3+

impurity**

  • 2.4 eV -> tetrahedral Mn2+

impurity**

  • 2.4 – 4 eV -> F, F+ centres +

complex intrinsic defects***

  • 4.5-6.5 eV -> “anti-site”

defects**

*Lushchik et al J. Lum. 102-103 (2003) **Gritsyna et al. Nucl. Instr. and Meth. in Phys. Res. B 250 (2006) ***Sawai, Uchino J. Appl. Phys. 103523 (2012) 11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 10

MgAl2O4 ceramics compared to a single crystal*

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Conclusions

  • Dense ceramics with various grain sizes and transparencies,

starting from UPA

  • Starting from a phase with smaller crystallite size does not

insure a smaller-grained ceramic

  • Pre-pressing leads to a tenfold increase in grain size
  • The spinel samples need annealing in air to get rid of

coloration

  • Slight fiber-like texture aligned with the pressure axis of SPS,

crystallites more spherical after annealing

  • High inversion level for spinels and common impurities

11/07/2017 Annika Pille annika.pille@lspm.cnrs.fr ECerS 2017 Budapest 11

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SLIDE 12

LSPM-CNRS Université Paris 13 99 Av J. B Clément 93430 Villetaneuse, France www.lspm.cnrs.fr Fax: +33 1 49 40 34 14

Thank you for your attention!

annika.pille@lspm.cnrs.fr

Acknowledgements: Université Paris 13 EUROfusion