Calcium-Doped Boron Nitride Aerogel Enables Infrared Stealth at High Temperature Up to 1300 °C

Abstract

Boron nitride (BN) aerogels, composed of nanoscale BN building units together with plenty of air in between these nanoscale building units, are ultralight ceramic materials with excellent thermal/electrical insulation, great chemical stability and high-temperature oxidation resistance, which offer considerable advantages for various applications under extreme conditions. However, previous BN aerogels cannot resist high temperature above 900 °C in air atmosphere, and high-temperature oxidation resistance enhancement for BN aerogels is still a great challenge. Herein, a calcium-doped BN (Ca-BN) aerogel with enhanced high-temperature stability (up to ~ 1300 °C in air) was synthesized by introducing Ca atoms into crystal structure of BN building blocks via high-temperature reaction between calcium phosphate and melamine diborate architecture. Such Ca-BN aerogels could resist the burning of butane flame (~ 1300 °C) and keep their megashape and microstructure very well. Furthermore, Ca-BN aerogel serves as thermal insulation layer, together with Al foil serving as both low-infrared-emission layer and high-infrared-reflection layer, forming a combination structure that can effectively hide high-temperature target (heated by butane flame). Such successful chemical doping of metal element into crystal structure of BN may be helpful in the future design and fabrication of advanced BN aerogel materials, and further extending their possible applications to extremely high-temperature environments.

Mechanically Reinforced Rigid Polyimide Foam via Chemically Grafting Isocyanate Acid for Ultrabroad Band Microwave Absorption

“…Apart from the excellent MA performance and high strength, because of the high porosity and low CNT content, the desirable thermal insulation ability was achieved, offering the potential infrared stealth application. − The thermal infrared shielding performance and temperature rise curve of CNT/PI foams placed on the heating platform (300 °C) are shown in Figure . The darker color of the foams’ top surface perfectly matches the surroundings at the original stage, although the thermal radiation has already started to transfer as observed in the side views.…”

Medium-entropy ceramic aerogels for robust thermal sealing

“…5e), which is beyond the reach of typical ceramic aerogels. 25,[57][58][59][60][61] We nally evaluated the practical thermal sealing performances of the MECA. We tested the MECA as a typical thermal seal between the joints in a spacecra (Fig.…”

“…Moreover, due to the insufficient oxidation resistance, large thermal expansion coefficient and serious crystallization-induced pulverization, ceramic aerogels still show insufficient thermostability under high temperature exposure or large temperature gradient. 10,11,24 The oxidation resistance and thermal expansion coefficient can be improved by elemental composition selection 25 and structural design. 7 However, it is more difficult to suppress the crystal growth and phase transition induced pulverization of ceramic materials when the system energy exceeds the crystalline barrier at high temperatures.…”

Mullite Nanosheet/Titania Nanorod/Silica Composite Aerogels for High-Temperature Thermal Insulation

“…3 In addition, in the aerospace and cogeneration industry fields, there is an urgent need for efficient insulation materials with excellent thermal and chemical stability to ensure equipment safety. 4 High-temperature insulation aerogel materials, such as SiC, 5,6 Si 3 N 4 , 7−9 BN, 10 SiO 2 , 11 and Al 2 O 3 , 12,13 have been developed considerably in recent years. However, practical application scenarios in high-temperature environments are often under oxygenated conditions, and among these materials, SiC, Si 3 N 4 , and BN, are not resistant to oxidative corrosion at high temperatures.…”

“…High-temperature insulation aerogel materials, such as SiC, , Si 3 N 4 , − BN, SiO 2 , and Al 2 O 3 , , have been developed considerably in recent years. However, practical application scenarios in high-temperature environments are often under oxygenated conditions, and among these materials, SiC, Si 3 N 4 , and BN, are not resistant to oxidative corrosion at high temperatures.…”