炭素系ナノ材料による金属材料の高次機能化－CNT分散金属基複合材料の特性－

1

Nitrogen solute Ti

TitaniumInterstitialOxygen
solution

224.51 g/cc

Ultra-fine
microstructure Mg alloy

CNT-Al compositeCarbon
nanotube

Aluminum

Magnesium

13122.70 g/cc

1.74 g/cc2

Tensile strength; 10～60 GPa
Young’s modulus; ~1 TPa

Multi-wall CNT

c.f Carbon steel
Tensile strength; 0.4～1.5 GPa
Young’s modulus; 0.21 TPa

3Properties

Single-walled

Multi-walledSteelSpecific gravity

0.8 g/cm3

1.4 g/cm3

7.8 g/cm3

Tensile strength

50～500 GPa

10～60 GPa0.4～1.5 GPa

Young’s modulus

1.4 TPa

1 TPa

0.21 TPa

Electric resistivity～1000 µ cm～200 µ cm

9.7 µ cm

Thermalconductivity

3 kW/m K

3 kW/m K

80 W/m K4

http://www.yonex.co.jp/golf/news

MWCNTs Reinforced
Composite Plastic

MWCNTs Reinforced Super Elasto-plastic
Titanium Alloy “GUM METAL”

5

Textile using CNTs coated yarns
B. Fugetsu, E. Akiba, M. Hachiya, M. Endo, Carbon, 47 (2009) 527-530.

6

MW-CNTs coated PET film
Surface electric resistance; 1.0ｘ105 Ω/□Transparency; 86.5%

B. Fugetsu et al., Carbon, 46 (2008) 1256-1258.

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Bundled CNTs

“Materials Defects”

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Mg powder + CNTs ➡ Composite

Fracture surface of Mg+3%CNT(No CNT)

Bundled CNTs

20μm

K. Kondoh et al., Mater Sci Eng A 527(2010) 4103-4108.
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CNTs coated on Al powder

Un-bundled CNTs dispersed water
solution with zwitterionic surfactant

K. Kondoh et al., Comp. Sci. Tech. 69 (2009)1077-1081.

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CNTs coated on Al powder

Un-bundled CNTs dispersed watersolution with zwitterionic surfactant

K. Kondoh et al., Comp. Sci. Tech. 69 (2009)1077-1081.

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13

CNTs coated powder

Powder pressing& vac. sintering

Secondary operation(rolling, forging, extr.)
Hot extrusion

Individual MWCNTs

MW-CNT

Wrought metal bars

14 Uniform dispersed un-bundled
CNTs reinforcements effective
for dispersion strengthening
due to load transfer at CNT-Al
matrix interface.
 HEBM causing breakage ofsome CNTs, and resulting in
not enough improvement ofdispersion strengthening effect.

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SEM observation on fractured surfaces of Al-1%CNT composite after tensile test16

Al matrix

Small Al4C3Good interfacial bondingof CNT to Al matrix by
Al4C3 formation17

Peeling18

In-situ tensile test equipment installed in SEM-EBSD system

B. Chen et al., Comp Sci. Technol 113 (2015) 1-8.

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Peeling slope

Peeling starts at bridge walls
inside multi-walls due to CNTs
original defects and severe
deformation in powder ball milling
B. Chen et al., Comp Sci Technol 113(2015) 1-8.
B. Chen et al., Micron 69 (2015) 1-5.
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Experimental

B. Chen et al., Comp SciTechnol 113 (2015) 1-821

Al atoms diffusion along (110) plane of CNT & formationof Al4C3 nano-rod with (001) structures in c-axis

SAD

(014)

(011)

(003)

(014)T(011)T

Al4C3 [100]d=0.286 nm

Twinned structure22

4Al4C3/Al composite

SAD

(014)

(011)

A B

(003)

(014)T(011)T

8Al4C3/Al composite

aAl4C3 [100]ba(114)T(111)TA

(003)

(114)
(111)(114)T(111)T(114)(111)

b
Al4C3 [110]Al4C3 [110]23BF-TEM

16Al4C3/Al

SAD
(014)
(011)

(003)

A

(014)T(011)T

B

Al4C3 [100]DF-TEM A

DF-TEM B

Five-twinned Al4C3 nanorod

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Al4C3 nano-rod(003)(220)Al-(011)(001)

Al4C3-(113)Al(313)AlB. Chen et al., Advanced Eng Mater 16 (2014) 972-975.
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After sintering

16mass%CNT
8mass%CNT
4mass%CNT

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Elemental mixture ofPure Al + Al4C3/Al comp powders

Al4C3 nano-rod

Strain rate: 5☓10-4 s-1

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TEM observation - Al+4%GNP**GNP; Graphene nanoplate
B. Chen, K. Kondoh, J. Umeda, M. Takahashi: Simultaneously enhancing strength and ductility of carbon
nanotube/aluminum composites by improving bonding conditions, Scripta Materialia, 113 (2016)158-162.
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1200

Ti-0.5wt%CNT composite

Stress, σ/MPa

1000

800

Pure Ti powder material
600

400

200

000.1

0.2

0.3

0.4Strain, εK. Kondoh, T. Threrujirapapong, H. Imai, J. Umeda,
B. Fugetsu: Characteristics of powder metallurgy
pure titanium matrix composite reinforced with multiwall carbon nanotubes, Composites Science andTechnology, 69 (2009) 1077-1081.
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30

Cu-CNT

Cu-C binary phase diagram

Pure Cu + 0.13 mass%CNT

CNT

CNT+Cu31

Cu + 0.13mass%CNT

Cu grain boundary

CNTs3μm

100nm(x 150,000)

CNTs at grain boundaries resulting in grain refinement by Zener drag ?

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Pure Cu sintered material
Sintering Temp: 873 K

T= 1073 K

T= 1223 K

20µm

Pure Cu + 0.13mass%CNT composite
Sintering Temp: 873 K

T= 1073 K

T= 1223 K

20µm

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Main strengthening factor➟ Grain refining, not CNTs disp.

Low work hardening➟ Low efficiency in load transferfrom CNTs to Cu matrix

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Al matrix

GNP❶低温にて安定な炭化物を合成❷Cuと安定な化合物を生成しない❸Cuに対する固溶限が極めて小さい
急冷凝固法によりCu粉末中に適切な元素を過飽和固溶⇒焼結過程で析出
➡CNTと反応➡炭化物合成 [Ti, Cr, V] 界面での炭化物の合成反応を促進

Gibb’s free energy in carbide formation,⊿G0 / cal･mol[C] -1

 安定な酸化物（酸化皮膜）内への炭素原子の拡散による界面での応力伝達

Temperature, T / ℃
出典 金属データブック（改訂３版） 日本金属学会編

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Cu-0.5%Ti + 0.4%CNT

Cu

CNT

Cu

100μm

Ti

CNT

C

300nm
500nm

SEM observation on Cu-Ti alloy
powder surface coated with CNTs

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CNTCuCu37

AZ31B; Mg-3%Al-1%Zn-0.3%Mn38

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Surface potential
Gradient compositionlayer at interface
Local cell(~1.1 v)InterfaceCNTX

Mg

Mg
Local cell at CNTs

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Al diffusion at CNT by heat treatment
Potential

Pure Mg + CNTs
Mg matrix

CNTs

Mg-6%Al + CNTs

C-D
Mg-Al

CNTs

Al-rich & Al2MgC2H. Fukuda et al., Mater Chem Phys 127 (2011) 451-458.
4240
3% NaCl solution immersion test (35℃ for 6hrs)

3Corr. Rate (mm /day)

35Matrix; Mg-6%Al-1%Zn (AZ61)

30
25

Without H.T.
○ As-sinteredWith H.T.
● Heattreated2015
10Al-Mg-C compounds
formation by H.T

500.0

0.5
1.01.52.0
Volmetric
fractionof CNT,VCNT/ vol %
Volumetricfractionof CNTs
(vol.%)
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炭素系ナノ材料による分散強化の発現➡凝集体の解消・単分散化が不可欠
炭化物形成による界面での応力伝達
多層CNTにおける内部欠陥 “Peeling”➡CNTの完全緻密化：nano-rod合成
分散強化以外のCNTの効果➡結晶粒微細化（Zener pinning）

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