2022/09/06
The 13th International Symposium of Advanced Energy Science～Research Activities on Zero-Emission Energy Network～

ZE2022C-01

Evaluation of thermal resistance at theinterface of candidate materials forfusion reactor divertor
Masafumi Akiyoshi (Osaka Prefecture Univ.)
Kiyohiro Yabuuchi (Kyoto Univ.)
Tatsuya Hinoki (Kyoto Univ.)

Miniature specimens
PHENIX Project: 2013-2018 6Year
PIE cannot wait the cooling.

Small specimen for thermal diffusivity
measurement is strongly required toreduce radio activity and volumetricheating during the neutron irradiation.

D10×T2Standard Specimen

D3×T0.5Miniature Specimen→ TEM Disk Size

1/44 Volume → 1/44 Radio-Activity

In the PHENIX project, irradiation in HFIR have been performed with the specimen formof Diameter 3mm ×Thickness 0.5mm (D3TH) for thermal diffusivity measurement.
Specially manufactured specimen holders enable the measurement of this D3TH miniature
specimens.
10mmInSb IR Detector
Put InRadiated IR

Rear aperture

As D10Specimen
D3 Specimen holder manufactured by Mo-TEM alloy.

φ3mm specimen

Specimen holder

Netzsch LFA-467HT
Standard Specimen Holder(For 12.7mm specimen,Pre aperture
Buffer ringwith 10mm Conversion ring)

Laser Flash
φ10 mmOscillation problem at high temperature

70・The annealing at 800℃ showed norecovery on the specimens irradiatedat 548℃ or 660℃.

5001: Pure W(⊥) TIrr 548℃
A000: K-doped W-3Re(⊥) TIrr 660℃

60

measurements up to 600, 700, 800, 900 ℃

・The measurement at 900℃ showed
cyclic noise on the IR signals, that issaid the Oscillation problem.

50

Therefore, we stop the annealing
procedure on the irradiated specimens.
740

6530

4Response

Thermal Diffusivity / mm2・s-1The annealing effect is estimated by isochronal annealing procedure. In addition, if there is some annealing
recovery, isothermal annealing behavior is evaluated from the measurement performed in every 1min at aimed
annealing temperature for 1h.

400

600

800

1000

32

1200

10Measurement Temperature / K

Calculation range

-1-50

050
Time /ms

100150200

Ultra High Purity Compact Gas Purifier
GP-05/-Ar-Ar-02SW was attached to LFA-467HT at Uji.
（Pureron Japan, gas flow:0.04～0.2L/min）
http://www.pureron.co.jp/english/product/gp/index.html
In addition, ultra high purity Ar gas was used to purge.

The graphene coating wasoxidized and vaporized toCO/CO2 gas at poor vacuum
or low purity inert gas.
Inlet: 1/4 inch
Teflon tube

10mm

GP-05/-Ar-Ar-02SW
Outgo: 1/8 inch
SUS tubeTo LFA-467HT
Parge2 /Protective port

FIX the oscillation at higher temperatureThick Graphene coat (20 push ofspray) on the D3TH specimen
gives good S/N ratio on IR signals.

Oscillation at high temperaturearisen from the oxidation was almost
inhibited with the gas purifier.

pulse width: 50μs, Laser power 260V(maximum)

A little oscillations were observed
at 1200℃ measurement.

-120 push spray of graphene coat504030500
1000
Measurement temperture / K

1500

605 push spray of graphene coat
D10T1 W specimen
D3TH1 W specimen
with 5push graphene coating

2D10T1 W specimen
D3TH1 W specimen
with 20push graphene coating

Thermal diffusivity / mm ・s

60

2

Thermal diffusivity / mm ・s-1

Too thick coating effect504030500
1000
Measurement temperture / K

1500

Too thick coated D3TH specimen showed lower
thermal diffusivity than the standard specimen.
In the previous study, thin coating specimens showed
low S/N IR curve with the flash measurement.
In addition, at high temperature, these thin coatingspecimens showed oscillation from low temperature.

How to achieve thismeasurement?

Effect of the D3 specimen holder

D10T1

D3TH

The Netzsch LFA-467HT have thezoom optics system at infraredmeasurement detector on the back of
the sample that enable to measuresmall specimen.

Measurements at 900℃ on D10T1 and D3TH W specimens with 20 pushgraphene coating showed different IR curve even the detective area of the zoom
optics was set to D2.8 mm for both specimens.
The reason for this difference was that this zoom optics system and the special
specimen holder for the D3 sample interfered with each other, resulting in adecrease in the amount of infrared light.
InSb IR Detector

InSb IR Detector

Zoom optics
view area
Rear apertureInterfere

Radiated IR
φ3mm specimen

Specimen holder

Pre aperture
Buffer ring

Remove thebuffer ring andthe rear aperture

Radiated IR
Specimen holder

φ3mm specimen

Pre aperture

Flash LightFlash Light

φ10 mm

φ10 mmFinal fix the oscillation problem

D10T1

Pure W specimens
with 5push graphene
coating

D3TH

Measured at 900℃

Using D3 specimen holder
without the buffer ring andthe rear aperture.

60
D10T1 W specimen
D3TH1 W specimen
with 5push graphene coating

2

Thermal diffusivity / mm ・s-1

Using gas purifier

50

D3TH specimen showed
good agreement withD10T1 specimen andshowed no oscillation.

4030500
1000
Measurement temperture / K1500