Preparation of V2O5 thin films on AA6061 alloy using thermal evaporation

Abstract

Spacecrafts often operate in severe environments with large exterior temperature fluctuations varying from −150 °C to +150 °C. Spacecraft internal parts work at their optimal efficiency between a range of temperatures, most likely between −10° C to 40 °C, beyond which they suffer damage. Consequently, good thermal management of spacecraft is required. The current technologies may become inadequate in the future owing to stringent requirements of micro- and nanosatellites, which entail the necessity of smaller and smarter thermal control subsystems. Traditional thermal technologies such as heaters, thermostats, heat pipes, coolers, and louvers will almost probably not be adequate to satisfy the requirements, since they are typically heavy and consume more electricity. Hence, Variable emittance coatings, which may modify the effective infrared emissivity and hence the radiative heat transfer rate, will be the inevitable potential choice for flexible or intelligent thermal management of spacecraft. Among all vanadium oxides, VO2 has been shown to exhibit a reversible phase shift at positive temperatures at 68 °C. This phase shift modifies its thermo-optical properties. Thermal evaporation was used to create V2O5 thin films on an AA6061 substrate, and subsequent reduction with N2 gas resulted in the creation of VO2. SEM, EDAX, and XRD were used to characterize the materials.