Development of Asbestos-free and Environment-Friendly Thermal Protection for Aerospace Application

Abstract

Thermal protection systems (TPS) are components designed to protect the internal and external areas of a rocket motor from high temperatures. There has been studies in Brazil of resin-based polybutadiene hydroxylated (HTPB) loaded with asbestos since the 1970s. Nevertheless, asbestos has been banned in several countries because it is severely harmful to the human health. In this context, the development of asbestos free in flexible thermal protection (FTP) is extremely important. This study evaluates the use of Expanded Perlite (PExp) as an asbestos substitute. Lower densities were observed, which become a very interesting achievement for the aerospace field. Samples with 5 phr of Expanded Perlite showed similar results when comparing with 47 phr of fillers in PTF reference on oxy-acetylene torch test, and a reduction about 20 % of mass loss rate in test with solid propellant, thus showing that Expanded Perlite can replace asbestos in FTP. Figure 1. Components of a rocket motor 15 .

Evaluation of elastomeric heat shielding materials as insulators for solid propellant rocket motors: A short review

“…Research in this field has increased significantly, and several excellent reviews have been published in recent years [7,[9][10][11][12] from leading countries such as China, India, Iran, Italy, Russia, and the United States. South American countries have also contributed to the development of materials in the field of rocket science [4,5,[13][14][15][16]. By forming an inner lining on the inner surface of rocket motors, insulators prevent their exposure to the extremely high-temperature gases of the propellant during combustion and help the integrity of motor without failure during operation [17].…”

“…The stronger and stable the char layer is, the slower the consumption of TPS will be, which results in a low ablation rate. Microstructure origin of heat shielding of temperatures in the range of 2,000-3,000°C is mainly the formation of a thick layer of char, which insulates the underlying material from the hot gases coming from burning propellant [5,6].…”

“…The ablation rate expresses the recession or consumption of the TPS material during a given amount of time ( Figure 2). According to ASTM E-285-08, this value is measured by the ratio between initial and final thickness and time during the ablation test [5,6].…”