AFFORDABLE AND
CLEAN ENERGY● High-temperature properties of oxide-based ceramic
matrix composites fabricated with novel mullite fibers
Advanced Materials Research Laboratory, TOSOH Corporation

Yushi NAWATA
Ikuya OHTA
Yo HIRATAKA
Isao YAMASHITA

Oxide-based CMCs (Ox/Ox CMCs), which are

1．Introduction

composed of oxide fibers and an oxide matrix, have

Ceramic matrix composites (CMCs) are designed

lower cost and better stability against corrosive andto overcome the brittleness of monolithic ceramicoxidative environments than SiC-based CMCs 6 .

materials while maintaining the advantages of high-Thus, Ox/Ox CMCs are promising candidates fortemperature stability, excellent mechanical properties,

high-temperature applications in various oxidizing

and low density. These materials are thus candidates

environments7.

for potential applications as thermally resistant

The thermal stability and high-temperature properties

materials, in aircraft engines, and in power-generatingof Ox/Ox CMCs are important factors for their practical

turbines as alternative to conventional nickel superapplications. We have developed a novel alumina-fiber-

1–3

alloys . For example, the use of CMCs for aircraft

based Ox/Ox CMC (TCA-01) and a novel mullite-fiber-

gas-turbine engines improves fuel efficiency andbased Ox/Ox CMC (TCM-01); both of them exhibit

reduces CO 2 reduction. The Leading Edge Aviationhigh thermal stability8,9.

Propulsion engine manufactured by CFM International,

In this technical report, we summarize the high-which employs a high-pressure gas-turbine shroud

temperature mechanical properties of the Ox/Ox

manufactured using SiC-based CMCs, achieved 15%

CMC TCM-01 that we have developed. Our purpose

higher fuel efficiency and 15% lower CO2 emissions thanin developing this CMC is to address Sustainable

4Development Goal 7 (Affordable and Clean Energy)

conventional gas-turbine engine .
Figure 1 shows the appearance of monolithic
ceramics and CMCs following nail-penetration tests.

and to contribute to society by providing novel Ox/Ox
CMCs.

The monolithic ceramics exhibit fully brittle failure.
However, the CMCs maintain their shapes due totheir high damage tolerance, which is achieved by2．Uniform doping method for oxide fibers

deflecting cracks along the weak fiber–matrix interface,

We have developed a novel uniform doping method

uncollected fiber failure, and energy dissipation during(UDM)8,9 to improve the thermal stability of oxide fibers

fiber pullout5.

and have used it to produce two Ox/Ox CMCs−TCA-01
and TCM-01−that exhibit high thermal stability. Figure
2 shows the UDM concept, which is a method of doping
oxide fibers (alumina and mullite) with grain-growth
inhibitors. This suppresses the grain growth of UDMtreated fibers during thermal exposure. Figure 3 shows
the tensile strengths of the developed Ox/Ox CMCs
as processed and after thermal exposure at 1200 ℃

Monolithic ceramics

Fig.１

CMCs

Nail penetration test 9）

for 1000 h. Neither of the two CMCs that used UDMtreated fibers exhibited a reduction in tensile strength
after thermal exposure8,9.
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TOSOH Research & Technology Review Vol.67（2023）

Non－treatedTensile strength［MPa］

350
Grain
Thermalexposure

Grain growth
Strength reduction
UDM treatedDopingelement

Oxide fiber（alumina or mullite）

Fig.２

Fig.３

Concept of uniform doping methods (UDM)

After 1200 ℃－1000 h250
200150100500

Suppression of grain growth
Keep strength

As processed

300TCA－01
Alumina fiber based

TCM－01
Mullite fiber based

Tensile strength of developed Ox/Ox as processed
and after 1200 ℃ for 1000 h thermal exposure9）

2 mm. The matrix phase filled the spaces between the3．Mechanical properties of the novel mullite-

woven layers of the pile and inside the fiber bundles.

fiber-based Ox/Ox CMC TCM-01

The density of TCM-01, measured using Archimedes’
method, was 2.62 g/cm 3, and the fiber volume was

We developed TCM-01 using UDM-treated mullitefibers and an alumina-based matrix and employing

about 45 volume %.

slurry infiltration and a sintering process to fabricate

Table 1 lists the mechanical properties of TCM-01,

it. Figure 4 shows optical and scanning electronof a commercially available conventional Ox/Ox CMC

microscope energy dispersive spectroscopy (SEM–using mullite fibers (N720/A ATK-COIC)10, 13−17, and ofEDS) images of TCM-01. The plate, consisting of fivea single-crystal nickel-based super alloy for gas-turbine

woven layers of this Ox/Ox CMC had a rectangularengines (CMSX-4 Cannon-Muskegon)12, 18. TCM-01 had

shape measuring 220 mm by 80 mm with a thickness ofbetter thermal stability than the conventional Ox/Ox

Top view
80mm
220mm

MatrixSectional view

MatrixFiber

Fiber bundle

2mm

Optical microscope image

Fig.４

SEM－EDS image

Optical image and microstructure of TCM－019）

Table１

Mechanical properties of TCM－01

Creep lifetime
Tensile strength Retention rate of tensile Tensile strength
at 1200 ℃, 100 MPa
at 1200 ℃
strength after 1200 ℃ forat R.T.
［h］［MPa］
1000 h［％］［MPa］
TCM－01Conventional Ox/Ox
Sigle crystal Ni－based
super alloy18316910）

103
8819216813－17）,※1

53.84114）

94212）－17212）1318）,※2※1 Average value of tensile strength in the references※2 At 1200℃, 80 MPa

74東ソー研究・技術報告

CMC. We observed no reduction in the tensile strength
retention of TCM-01 after being held at 1200 ℃ for1000 h; in contrast, the tensile strength retention of theconventional Ox/Ox CMC was 88%10,11.

第 67 巻（2023）

4．Tensile properties of TCM-01 at hightemperature
We performed high-temperature (800–1250 ℃ )The tensile properties of TCM-01 at 1200 ℃ weretensile tests based on the American Society for Testing

better than those of either the single-crystal nickel-and Materials (ASTM) C1359 standard in air using

based super alloy or the conventional Ox/Ox CMC.

a mechanical test machine (MTS Landmark MTS

The tensile strength of TCM-01 at 1200 ℃ was 192

Systems Corporation) and a strain gage (MTS SystemMPa, and no significant reduction in tensile strength

Corporation). The constant displacement rate was 3.00

was observed up to 1250 ℃ . For comparison, themm/min, and we increased the temperature at thetensile strength of a single-crystal nickel-based superrate of 35 ℃/min. We calculated the strain from thealloy at 1200 ℃ was 172 MPa, a significant degradation

crosshead displacement. We used dog-bone-shaped

12compared to the results obtained at 24 ℃ (942 MPa) .

specimens (150 mm long, with an 8-mm-wide gage

The tensile strength retention (ratio of tensile strengthsection). We evaluated the tensile modulus, tensile

at 1200 ℃ to room temperature) was 18%. Similarly,

strength, and proportional limit (0.05% offset). The

the tensile strength of the conventional Ox/Ox CMC

tensile properties over the range 25–1250 ℃ are listed

at 1200 ℃ was 168 MPa (this value is average value ofin Table 2. Figure 5 shows the stress–strain curves

13–17

tensile strength in the references)

over the range 25–1250 ℃ , together with the shape and.

The creep lifetime of TCM-01 at 1200 ℃ also wasdimensions of the test specimen. Figure 6 shows thebetter than that of either the single-crystal nickel-basedtensile properties of TCM-01 at different temperatures.

super alloy or the conventional Ox/Ox CMC. The time

We observed no significant reduction in the tensile

to rupture of TCM-01 at 1200 ℃ was >100 h at 80 MPa

modulus, tensile strength, or proportional limit up

and 53.8 h at 100 MPa. In contrast, the time to rupture

to 1250 ℃ . Thus, TCM-01 exhibited superior tensile

the single-crystal nickel-based super alloy at 1200 ℃

properties at high temperatures up to 1250 ℃ .

18

was only 13 h at 80 MPa , while that of the conventionalOx/Ox CMC at 1200 ℃ was 41.0 h14 at 100 MPa.
Furthermore, TCM-01 exhibited low thermal
conductivity and a high electrical resistivity. The

5．Fatigue properties of TCM-01 at hightemperaturethermal conductivity was 3.3 W/(m/K), which we

We performed high-temperature tension–tension

calculated from the thermal diffusivity evaluatedfatigue tests in air using a mechanical test machine

following ASTM E1461, the specific heat, and the(MTS Landmark 370.10 MTS Systems Corporation)

14density. The electrical resistivity was 1.9 × 10 Ω cm,and a strain gage (MTS 632.53F-14 MTS Systemwhich we evaluated following JIS C2141 and JIS C2139,Corporation) based on ASTM C1360. The R ratio (theat an applied voltage of 1000 V and a test temperature ofminimum stress divided by the maximum stress)

25 ℃ .

was 0.05 at a frequency of 1 Hz, and the fatigue run-Table２

Tensile properties of TCM－01 at high temperatures modulus Proportional limit※1 Tensile strength※2
Test Temperature Youg’
［GPa］
［MPa］
［MPa］
［℃］
70.6
141
183
2560.9
125
181
800
61.0
123
194
1000
61.6
123
194
1000
69.6
127
193
1100
66.2
105
195
120057.71171801250※1 0.05％ offset method，※2 following ASTM C 1359

75

TOSOH Research & Technology Review Vol.67（2023）

250

RT800 ℃
1000 ℃－11000 ℃－21100 ℃
1200 ℃
1250 ℃
1330 ℃

Stress［MPa］

200

150

10050

000.002

0.004

0.006

0.008

（b）Appearance of tensile test specimens

10 mm

Strain［－］（a）Stress－strain curves

Fig.５(a) Stress－strain curves of TCM－01 and (b) appearance of tensile test specimen

250806050

150401003020Tensile strength50

Proportional limit
010Young’s modulus
0200400Young’s modulus［GPa］

Tensile strength
or proportional limit［MPa］

702006008001000

120001400

Temperature［℃］Fig.６

Tensile properties of TCM－01 at different temperatureout cycle was 105. The test temperature was 1200 ℃ ,and temperature was increased at 35 ℃/min. For

6．Creep properties of TCM-01

this test, we used dog-bone-shaped specimens (200We performed creep tests in air using a mechanicalmm long, with an 8-mm-wide gage section). The test

test machine (MTS Landmark 370.10 MTS Systems

results are listed in Table 3, and Figure 7 shows theCorporation) and a strain gage (MTS 632.53F-14 MTS

typical evolution of a stress–strain hysteresis loop. TheSystem Corporation) based on ASTM C1337. We usedmaximum stress at run-out at 1200 ℃ was 140 MPa (70%the same dog-bone-shaped specimens as for the fatigueof the ultimate tensile strength at 1200 ℃ ). Thus, TCM-test. The test temperatures were 1100, 1150, and 1200

01 has high fatigue resistance at high temperatures and℃. The stress rate was 15 MPa/s, and the temperaturein environments with high applied stress.

was increased at the rate of 35 ℃ /min. The time ofcreep run-out was 100 h. The test results are listed

76東ソー研究・技術報告第 67 巻（2023）

Results of fatigue tests of TCM－01

Table３

Test temperature［℃］Maximum stress［MPa］ Cycle to failure［－］
1200
100
100,000※
1200
125
100,000※
1200
140
100,000※※Run－out

1 cycle2 cycle180

3 cycle4 cycle160

5 cycle6 cycle7 cycle140

8 cycle9 cycleStress［MPa］

120

10 cycle
50 cycle100

100 cycle
500 cycle
1000 cycle

805000 cycle
10000 cycle

60

20000 cycle
30000 cycle

40

40000 cycle
50000 cycle

20

60000 cycle
70000 cycle

080000 cycle

00.002

0.004

0.006

0.008

0.01

0.012

0.014

100000 cycle

Strain［－］Fig.７

90000 cycle

Typical evolution of a stress－strain hysteresis loop (1200 ℃，140 MPa)in Table 4, and Figure 8 shows typical creep strain–

min, and get exposed to air. Air quenching temperaturetime curves. Figure 9 shows the relationship between

differences (ΔT ) is in the range of 0 ℃ to 1175 ℃ .We

the creep stress and the time to rupture. Run-out

performed the tensile tests using a screw-driven

occurred at a creep stress of 100 MPa at each of the test

universal mechanical test machine (MTS CriterionTM

temperatures 1100 ℃ , and 1150 ℃ . Therefore, TCM-01

Model 45 MTS Systems Corporation). The constant

has high creep resistance at high temperatures and in

displacement rate was 0.50 mm/min. Figure 10 showsenvironments with high applied stress.

the relative tensile strength of TCM-01 at different ΔT .
No remarkable reduction was observed in the relative
tensile strength (tensile strength after thermal shock

7．Thermal shock properties of TCM-01

test/tensile strength to that before thermal shock

We performed thermal shock experiments bytest) of the developed Ox/Ox CMC with ΔT . Thus,

heating the specimens to different temperatures in athese results confirm that the developed Ox/Ox CMC

vertical tubular air furnace at a heating rate of 4 ℃ /exhibited thermal shock resistance.

Table４Results of creep tests of TCM－01

Stress Time to rupture Rupture strain
Test temperature［℃］［MPa］［h］［%］
1100
100100※－1150
100100※－120080100※
－
1200
100
53.82.98※Run－out77

TOSOH Research & Technology Review Vol.67（2023）

0.012

0.010

Strain [［－］

0.008

0.006

0.004

0.002

0.000

050000100000150000200000 250000 300000 350000 400000
Time［s］

140

Test temperature:1200 ℃

Applied stress［MPa］

12010080

Run－out60
TCM－0140

Conventional Ox/Ox CMC14）200

Single crystal nickel－based
super alloys18）
020

40

60

80

100

120

140

Relative tensile strength［－］(After thermal shock test/before test)

Typical strain－time relationship (1200 ℃，80 MPa)

Fig.８

1.2
1.0
0.8
0.6
0.4
0.2
0.0

0

Creep stress vs time to rupture at 1200 ℃

8．Conclusion

4006008001000

12001400

Air quenching temperature differences［℃］Time to rupture［h］

Fig.９

200

Fig.10 Effect of quenching temperature difference on relative
tensile strength of TCM－01

We conclude that the Ox/Ox CMC developed inthis study can be employed in energy-related materials

In this technical report, we have summarized the−particularly thermally resistant materials, aircraft

high-temperature mechanical properties of TCM-turbines, and power turbines−where long-term

01 using UDM-treated mullite fibers. We found thethermal stability and superior mechanical properties arethermal stability of TCM-01 to be better than that of arequired at high temperatures.

conventional Ox/Ox CMC after being held at 1200 ℃for 1000 h. Additionally, both the tensile strength andthe creep lifetime at 1200 ℃ were better than thoseAcknowledgmentsof either a single-crystal nickel-based super alloy or

The authors thank Professors Yutaka Kagawa anda conventional Ox/Ox CMC. TCM-01 also exhibited

Yoshihisa Tanaka at The Center for Ceramics Matrix

thermal shock resistance. A further increase in theComposites at Tokyo University of Technology forthermal stability can be expected applying UDM andthe use of their evaluation equipment and useful

optimizing fabrication process.

discussions.

78東ソー研究・技術報告第 67 巻（2023）

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