Preliminary findings: Relationship between grain size, grain boundary g g yorientation and strength for the SiC layer of TRISO coated particles.I.J. van Rooyena, J.A.A. Engelbrechtb, J. H. Neethlingb,

P.M van Rooyenc, J. Riesterera, M.L Dunzik-Gougard

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a Idaho National Laboratory, United States of Americab Nelson Mandela Metropolitan University, South Africac Philip M van Rooyen Network Consultants, South Africad Idaho State University United States of America

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d Idaho State University, United States of America

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2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

Agenda

I t d ti• Introduction• Experimental plan• Preliminary resultsy• Conclusions• Acknowledgements

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

Introduction• Typical research questions which still needs answers and understanding:

– What is effect of very high temperature annealing on the microstructure and mechanical properties of SiC?

– What is the effect of neutron irradiation on the microstructure and mechanical properties of SiC?

– What is the predominant transport mechanism in SiC for fission products like Ag Cs I etc?like Ag, Cs, I, etc?

– What impact does grain properties (size, texture, grain boundary angles) have on the mechanical properties of SiC and how does it change as a result of neutron irradiation? Does it have any impact on Ag transport y p g pmechanism in SiC?

• Golden opportunity exists:y– lessons learned from previous research work and available data &

samples– examination of actual AGR-1 irradiated TRISO coated particles

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

Experimental Plan: Integration of “old” with “new”p g

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

Preliminary results

TRISO Coated Particles(ex PBMR)

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

TRISO CPs

BatchSiC Deposition

Temperature(ºC)

SiC Deposition

Rate (µm/min)

WeibullModulus

m

SiC Thickness

(µm)

SiC Density( 3)(ºC) Rate (µm/min) m (µm) (gcm-3)

G118 (ACF) **1510 * 4.33 32 3.19( C )

G146 (ACF) 1450 0.23 2.61 39 3.2

G169 (ACF) 1510 0.24 5.09 32 3.2

B14 (RCF) 1585 0 17 2 15 30 3 19B14 (RCF) 1585 0.17 2.15 30 3.19

B10 (RCF) 1510 0.17 5.03 30 3.19

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

EBSD Examination matrixEBSD Examination matrix

Batch

Selected info for CVD

reactors used for SiC

production

Post-production annealing conditions

Reference(no

annealing)

1000°C 1300°C 1500°C 1600°C 1700°C 1600°C 1800°C 1900°C 1980°C 2000°C 2100°C

1h 1h 1h 1h 1h 100h 1h 1h 1h 30min 10min

ACFG118 ACF1510°C NMMU NMMU NMMU NMMU NMMU NMMU NMMU NMMU NMMU NMMU NMMU NMMU

G146 ACF1450°C ISU ISU ISU ISU ISU

ACFG169 ACF1510°C ISU ISU ISU ISU ISU

B14 RCF1585°C NMMU NMMU ISU ISU ISU ISU ISU

B10 RCF NMMU NMMU ISU ISU ISU ISU ISUB10 1510°C NMMU NMMU ISU ISU ISU ISU

Samples for ISU studies arrived 14 January 2012EBSD at NMMU will start week of 23 January 2012

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

EBSD at NMMU will start week of 23 January 2012

Preliminary results

© CSIR 2006 www.csir.co.zaVan Rooyen et al. HTR2010.

Preliminary resultsVan Rooyen et al. HTR2010.

Results not complete: Only initial resultsResults not complete: Only initial results to confirm sample preparation technique (No conclusions is reached on results: measurements & interpretation will be done during January – March 2012)

:

Preliminary results: Compression strength

C i St th2.00

G118 (ACF)ā = 1090 MPa

Preliminary results: Compression strength

Compression Strength (between soft anvils)

0.00

1.00

ā = 1090 MPaσ0 = 1191 MPam = 4.35

B14 (RCF)ā = 1550 MPaσ0 = 1644 MPam = 7.59

‐2.00

‐1.00

ln[ln

[1/(1‐F i)]] 

G146 (ACF)ā = 860 MPaσ0 = 987 MPam = 1.86

‐4.00

‐3.00

G169 (ACF)ā = 1160 MPa

1268 MP

B10 (RCF)ā = 1520 MPaσ0 = 1586 MPam = 10.93

‐5.00

5.00 5.50 6.00 6.50 7.00 7.50 8.00ln[σf(MPa)]

σ0 = 1268 MPam = 4.56

10

1 hour annealing at 1600°C (ā = average strength, σ0 = characteristic strength and

m = Weibull modulus)Van Rooyen et al. J. Nucl. Mater.

Preliminary results: Characteristic strength-Temp

180025

16001800

2000

Preliminary results: Characteristic strength-Temp

2100

1200

1400

1600

gth

(MPa

)

160025

2000

800

1000

1200

teris

itc S

tren

g

400

600

Cha

ract

G118 (ACF)

G146 (ACF)

G169 (ACF)

B14 (RCF)

0

200

0 500 1000 1500 2000 2500

Annealing Temperature (ºC)

B14 (RCF)

B10 (RCF)

TREND SUGGESTEDCharacteristic Strength RCF batches >ACF batchesRCF Strength levels out at 1600°CPossible increase at 1800°C? Van Rooyen et al. J. Nucl. Mater.

1800

2000

Preliminary results: SiC-IPyC Interlayer - Strength

1400

1600

1800

gth

(MPa

)

800

1000

1200

teris

tic s

tren

g

200

400

600

Cha

ract

(ACF)(RCF)

00 0.5 1 1.5 2

Interlayer thickness (µm)

( )

TREND SUGGESTEDNeeds to standardize interlayer measurementStandard deviation (Error bar)

Van Rooyen et al. J. Nucl. Mater.

Preliminary Results: Nano IndentationPreliminary Results: Nano Indentation50

1980160025

100040

a]

2100

30

Har

dnes

s [G

Pa

20 CPT-T-G118

CPT-T-B14

CPT-B-B10

200010

0 500 1000 1500 2000 2500

Temperature [deg C]

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

Van Rooyen et al. HTR2008, ICACC 2010

Preliminary results

TRISO Coated Particles(AGR-1)

• No actual EBSD measurements on irradiated AGR-1 TRISO coated particles were completed yet but is planned.

S l ti t di d t k i t ll d– Sample preparation studies were undertaken in controlled environments to do EBSD measurements on metallographic prepared samples (to eliminate time on overloaded FIB)

– Limited time available on electron microscopes (focus firstly on ted t e a a ab e o e ect o c oscopes ( ocus st y omicrostructure and fission product precipitates)

© CSIR 2006 www.csir.co.za

Conclusions

Thi j t ill id l bl ti lt i th t 12• This project will provide valuable comparative results in the next 12 months where the integration of the results will be adding value

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012

Acknowledgements

PBMR f i iti l f di f TRISO t d ti l & li• PBMR for initial funding for TRISO coated particles & annealing • Johannes Mahlangu (annealing ) & Motshudi Mokoduwe (ASTM grain

size)• Jaco Olivier, Justin Downey & William Goosen for nano hardness

measurement & initial EBSD

2nd Workshop on HTGR SiC Material Properties, Idaho Falls, 19 - 20 Jan 2012