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Dr. Cheryl Xu Research Group

BNNT Reinforced Ceramic Composites

Future deep space missions, such as the mission to Mars, will be very dangerous due to space hazards such as micro-meteorites and ionizing radiation. These missions will require advanced materials to survive the harsh environment of space. This work aims to develop a multifunctional ceramic composite that can be integrated into current space technologies including entry, descent, and landing (EDL) systems, astronaut suits, and inflatable space structures. The ultimate goal is to develop a composite with the following properties: excellent toughness, high thermal stability, and efficient space radiation shielding.

Boron nitride nanotubes (BNNTs) are a new type of nanomaterial with incredible properties. Such properties include high thermal stability (up to 900 °C in air), high elastic modulus (~1 TPa), and the ability to shield neutron radiation. These properties make BNNTs an ideal reinforcing material for space application. Polymer derived ceramics (PDCs) are a unique type of ceramic that are produced by the thermal decomposition of polymer precursor. They are known for their advanced thermal-mechanical properties such as their excellent oxidation and creep resistance at ultrahigh temperatures (up to 2000°C). Creating a BNNT-PDC material would combine all these incredible properties to create an advanced composite suitable for space.

Figure 1. Major hazards in space environment (Thibeault, S.A., et al., MRS Bulletin 40.10 (2015): 836-841).

Figure 2. SEM surface view of BNNT reinforced ceramic composite.

 

Figure 3. Room temperature thermal conductivity of pristine polymer derived ceramic (PDC) and 35.4vol.% boron nitride nanotube (BNNT)‐PDC nanocomposites compared to other PDC composites (45vol.%Cf/PDC, 45vol.%Cf+10vol.%CNT(short)/PDC, 45vol.%Cf+10vol.% CNT(long)/PDC).

FIGURE 4. Change of thermal conductivity (A) and heat capacity (B) as functions of elevated measurement temperature.
 

FIGURE 5. Comparing the dielectric properties of BNNT reinforced ceramic composites with other typical ceramics (or ceramic composites) with similar dielectric property for EM transparent applications, frequency overlapping the Ka band.