SiAlON Ceramics Hasan Mandal Sabanc University, Istanbul, TURKEY - - PowerPoint PPT Presentation

▶
sialon ceramics
SMART_READER_LITE
LIVE PREVIEW

SiAlON Ceramics Hasan Mandal Sabanc University, Istanbul, TURKEY - - PowerPoint PPT Presentation

Aug 12, 2023 34 likes •408 views

Grain Boundary Engineering for Improved Mechanical Properties in SiAlON Ceramics Hasan Mandal Sabanc University, Istanbul, TURKEY MDA Advanced Ceramics Ltd, Eskisehir, TURKEY Si 3 N 4 and SiAlON s -Si3N4 -Si3N4 a= 7.76 c=5.62 a=

slide-1
SLIDE 1

Grain Boundary Engineering for Improved Mechanical Properties in SiAlON Ceramics

Hasan Mandal

Sabancı University, Istanbul, TURKEY MDA Advanced Ceramics Ltd, Eskisehir, TURKEY

slide-2
SLIDE 2

Si3N4 and SiAlONs

Si6-zAlzOzN8-z

Si+4 Al+3 N-3 O-2

Mem/valSi12-(m+n)Alm+nOnN16-n

Si+4 Al+3 N-3 O-2

-Si3N4 a= 7.61 Ǻ c= 2.91 Ǻ -Si3N4 a= 7.76 Ǻ c=5.62 Ǻ

slide-3
SLIDE 3

SiAlONs

α-Si3N4 +AlN/Al2O3 + Sintering additives

α-SiAlON β-SiAlON α-β SiAlON* Grain Boundary phase

+ (Y2O3, rare earths)

*Reversible α→β SiAlON Transformation in Heat-Treated Sialon Ceramics Mandal et al, 1993, Journal of European Ceramic Society

slide-4
SLIDE 4

SiAlONs

α-SiAlON β-SiAlON α-β SiAlON

Hard Tough Hard & Tough

slide-5
SLIDE 5

Cutting Inserts

image courtesy of CeramTec Germany

Turbochargers

image Courtesy of NGK/NTK Spark Plug Co

Bearing Applications Swirl Chamber

image courtesy of Kyocera company

Application Areas of Si3N4 and SiAlONs

slide-6
SLIDE 6

Wind Turbine Parts

Potential Application Areas of Si3N4 and SiAlONs

paper processing dewatering tiles Diesel particulate filters Cutting blades for wood machining mineral processing tiles Sand Blast Nozzle Liners

slide-7
SLIDE 7

DESIRE

Wider mechanical, chemical and refractory applications Properties in severe conditions Cost of powders and processing

CHALLENGES DEVELOPMENT STRATEGIES

Phase relationships and grain boundary chemistry

slide-8
SLIDE 8

50-200 nm Triple Junction Phases (TJs) Film Thickness 1-5 nm α-SiAlON β-SiAlON β-Si3N4 Si O Y Ca Yb+2/+3 Sm+2/+3 Ce+3/+4 Fe+2/+3 Er Al N Crystalline ? Amorphous ? Lattice parameters are different!!! > 10 nm Reinforcing Additives (SiC, TiN)

SiAlON Cocktail

slide-9
SLIDE 9

EFFECT OF INTERGRANULAR PHASE CHEMISTRY

slide-10
SLIDE 10

La3+ La3+ La3+ La3+ La3+ La3+ La3+ La3+ La3+ La3+ Lu3+ Lu3+

High Absorption High Anisotropy Low Interfacial Strength

La3+ Si2ON2 Lu3+ Lu2Si2O7

Low Absorption Low Anisotropy High Interfacial Strength

Crystalline Grain Boundary Phases

Hoffmann, M.J. and Satet R., “Impact of Intergranular Film Properties on Microstructure and Mechanical Behavior of Silicon nitride”, Key Eng.

  • Mater. Vols. 264-268, (2004), 775-780.

Shibata, N., Pennycook S., Gosnell, T.R., Painter, G.S., Shelton W.A. and Becher P.F.”Observation of rare earth segregation in silicon nitride ceramics at subnanometre dimensions”, Nature, Vol 428, (2004), 730-733

slide-11
SLIDE 11

SINTERING ADDITIVES FOR / SiAlON CERAMICS DEVELOPED by MDA

  • CaO

(To avoid  SiAlON transformation)

  • Y2O3 and/or Re2O3 (where ZRe62)

(To increase the stability and hardness

  • f -SiAlON)
  • Re2O3 (where ZRe<62)

(To develope elongated -SiAlON grains and increase fracture toughness)

US Patent No: US 7,064,095 B2 EP Patent No: 1 414 580 B1 2002

slide-12
SLIDE 12

PROCESSING

  • Powder:

– α-Si3N4 (SN E-10, UBE/Japan)

  • Composition:

Total additive content: 6.5 vol% Designed phase composition: 25% α-SiAlON - 75% β-SiAlON

(x:0.42, m=1.25, n=1.3) (z = 0.2)

:Sm:Ca Y Er Yb

Heat treatment above eutectic (AET) to enable crystallisation of sintering additives

slide-13
SLIDE 13

(i) EFFECT OF DOPANTS CATION SYSTEMS Yb 1Yb:1Ce Ce Yb:Sm:Ca Y:Sm:Ca Y:Ce:Ca Sintering Ss/Ys

  • MW

MS (ii) EFFECT OF HEAT TREATMENT CATION SYSTEMS Yb Yb:Sm Yb:Sm:Ca Y:Sm:Ca Y:Ce:Ca Sintering Ss/Ys

  • MW

MS HT-1500 Ss/Ys Ss/Ys Sw/Yw , Mw HT-1600 Ss/Ys Mw Ms Mvs

CRYSTALLISATION-AFFECTING FACTORS

Y: Ln4SiAlO8N ; S: Ln2Si2O7 ; M: Ln2Si3-xAlxO3+xN4-x EP12185237, OZ12031EP-Q2/BR, 20 September 2012

slide-14
SLIDE 14

Crsytalline Triple Pockets Amorphous Intergranular Films Amorphous Mini Triple Pockets Desired crystalline triple pocket Undesirable crystalline triple pocket tip

Good or Bad Crystallinity!

EP12185237, OZ12031EP-Q2/BR, 20 September 2012

slide-15
SLIDE 15

Good or Bad Crystallinity!

SiAlON Grain SiAlON Grain

Insufficient Crystallisation Good Crystallisation

Triple pocket (Fully crystalline) Triple pocket (Partially crystalline)

Amorphous regions

SiAlON Grain SiAlON Grain

slide-16
SLIDE 16

Y-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

Crystalline Secondary Phase    

slide-17
SLIDE 17

Y-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

Amorphous Secondary Phase    

slide-18
SLIDE 18

Y-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

Amorphous Mini Triple Pocket    

slide-19
SLIDE 19

Er-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

    Crystallization Degree of Mini Triple Pockets

slide-20
SLIDE 20

Er-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

   

slide-21
SLIDE 21

Er-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

    Crystallization Degree of Triple Pockets

slide-22
SLIDE 22

Er-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

    Crystallization Degree of Triple Pockets

slide-23
SLIDE 23

 

Er-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

  Crystallization Degree of Triple Pockets

slide-24
SLIDE 24

Yb-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

    Crystallization Degree of Secondary Phases

slide-25
SLIDE 25

Yb-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

Crystallization Degree of Mini Triple Pockets

 

slide-26
SLIDE 26

Yb-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

 

Crystallization Degree of Mini Triple Pockets Crystallization Degree of Mini Triple Pockets

slide-27
SLIDE 27

Yb-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

  Crystallization Degree of Secondary Phases

slide-28
SLIDE 28

Yb-Sm-Ca Added /-SiAlON System (1990 oC sintered and AET)

Crystallization Degree of Secondary Phases  

slide-29
SLIDE 29

Si3N4

Comparison of Creep Behavior of Si3N4 and α/β-SiAlONs

@ 1400 °C & 100 MPa

slide-30
SLIDE 30

Flexural strain % Time (h)

Yb Er

Yb versus Er

slide-31
SLIDE 31

Effect of Crystallinity on the Performance

40% improvement in life time Less wear

slide-32
SLIDE 32

DESIRE

Wider mechanical, chemical and refractory applications Properties in severe conditions Cost of powders and processing

CHALLENGES DEVELOPMENT STRATEGIES

Phase relationships and grain boundary chemistry

slide-33
SLIDE 33

2 m

α-β SiAlON from -Si3N4 powder containing impurities

D50 = 5 µm

Al2O3 MgO CaO Fe2O3 TiO2 β-Si3N4 1,4 ≤0,05 0,40 0,60 0,07

slide-34
SLIDE 34

Microstructures of SiAlON from different particles size β –Si3N4 powders

2µm 1µm 0.5µm

As-sintered Heat treated

slide-35
SLIDE 35

Impurity/dopant incorporation into β-SiAlON

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 keV LG10002 100 200 300 400 500 600 700 800 900 1000 Counts

N O Al Si Cr Fe Fe Cu Cu Cu

LG1 LG1 1.0 µm 1.0 µm 1.0 µm 1.0 µm 1.0 µm

STEM-HAADF Image Fe Si6-z(Al,Fe)zOzN8-z

slide-36
SLIDE 36

Cost reduction

  • Use of coarse and/or impure and/or -Si3N4 powders
  • Increased amount of (crystallizable) liquid phase
  • Lower temperature and/or pressureless sintering

Improved grain boundary crystallization Transient liquid phase sintering Impurity incorporation

to enable

slide-37
SLIDE 37

MARKET SIZE

  • BETTER PROPERTIES
  • COST

Conclusion

Opportunities are present to increase the applications of SiAlON based ceramics by chemistry and process improvement.