Aerogels are considered the lightest solid in the world, and are widely used in aerospace materials because of their high specific surface area and low thermal conductivity. In 1999, the National Aeronautics and Space Administration (NASA) developed a silica aerogel with a density of 3 mg/cm3, becoming the lightest solid material in the world. However, due to the brittleness and humidity sensitivity of silica aerogels, NASA has been supporting the development of durable aerogels for many years.
Silica aerogel material
Based on the needs of a lightweight and flexible supersonic gas decelerator for spacecraft landing, researchers at the NASA Glen Research Center (GRC) first carried out the study of polymer enhanced silica aerogels to enhance their durability. It was found that the polymer enhanced silica aerogel had a double density and a specific surface area reduction of 30% to 50% compared to the silica aerogel insulation blanket, but the strength increased by two orders of magnitude.
Polymer enhanced silica aerogels enhance durability
Nevertheless, its strength can not meet the requirements of spacecraft deceleration materials. Since then, a polyimide aerogel with eight amino phenyl (POSS) cross-linking has been developed in collaboration with University of Akron. A polyimide aerogel with a density of 0.12 g/cm3 and a porosity of 90% has been prepared. This material can withstand temperatures of 1100 F to 90 s, thus ensuring that it does not burn when entering the atmosphere. The strength is 5 times higher than that of polymer enhanced silica aerogels, and can be made into materials with thinner (0.5 mm) thickness to meet the requirements of collapsible storage in spacecraft. It overcomes the shortages of silicon aerogels in weight, cost, flexibility and durability.
Flexible polyimide aerogels
Based on aerogels and fiber materials, NASA began to develop multifunctional composite materials that could meet the requirements of spacecraft structural materials and thermal protection materials. For example, NASA Kennedy Space Center (KSC) researchers have developed a multi-functional manufacturing method of aerogel / fiber hybrid laminated composite materials, which can be made of different functional or multi-functional composite materials by selecting different fiber layers (such as polyester, carbon fiber, Kevlar fiber, Spectra fiber, Innegra fiber or their combination), different aerogel layer thickness and different composite structures. Material. This lightweight, high-strength multi-functional composite material can meet the requirements of aerospace vehicle in heat protection, shock resistance, energy absorption, sound absorption and other fields, and can be used in automobiles, ships, buildings, liquefied natural gas transportation, sports equipment and military protection.
Aerospace application case: inflatable reducer
In order to realize the manned Mars landing plan, NASA is developing heavy-load transportation technology. Supersonic inflatable pneumatic reducer (HIAD) is a solution that can provide effective load and volume benefit for spacecraft braking. In 2006, NASA set up a project called Advance Inflatable Decelerators for Atmospheric Entry (PAIDAE), and developed a HIAD with a diameter of 3-12 m consisting of an outer layer, an insulating layer and an airtight layer.
Civil case: outdoor clothing and equipment
In 2015, In addition to pipe insulation products used in extreme environments, developing polyimide aerogels for high-end outdoor products such as outdoor clothing, gloves, boots, tents, etc.